Java基础深化和提高-------容器篇

public class 类名<泛型标识符号> {  }
public class 类名<泛型标识符号,泛型标识符号> {  }

public class Generic<T> {
  private T  flag;
  public void setFlag(T flag){
    this.flag = flag;
 }
  public T getFlag(){
    return this.flag;
 }
}

public class Test {
  public static void main(String[] args) {
    //创建对象时，指定泛型具体类型。
    Generic<String> generic = new Generic<>();
    generic.setFlag("admin");
    String flag = generic.getFlag();
    System.out.println(flag);
    //创建对象时，指定泛型具体类型。
    Generic<Integer> generic1 = new Generic<>();
    generic1.setFlag(100);
    Integer flag1 = generic1.getFlag();
    System.out.println(flag1);
 }
}

public interface 接口名<泛型标识符号> {   }
public interface 接口名<泛型标识符号,泛型标识符号>{   }

public interface IGeneric<T> {
  T getName(T name);
}
//在实现接口时传递具体数据类型
public class IgenericImpl implements
Igeneric<String> {
  @Override
  public String getName(String name) {
    return name;
 }
}
//在实现接口时仍然使用泛型作为数据类型
public class IGenericImpl2<T> implements
IGeneric<T>{
  @Override
  public T getName(T name) {
    return name;
 }
}
public class Test {
  public static void main(String[] args) {
    IGeneric<String> igeneric= new  IGenericImpl();
    String name = igeneric.getName("old");
    System.out.println(name);
    IGeneric<String> igeneric1 = new IGenericImpl2<>();
    String name1 = igeneric1.getName("it");
    System.out.println(name1);
 }
}

//无返回值方法
public <泛型标识符号> void getName(泛型标识符号name) {  }
//有返回值方法
public <泛型标识符号> 泛型标识符号 getName(泛型标识符号 name) {  }

public class MethodGeneric {
  public <T> void setName(T name){
    System.out.println(name);
 }
  public <T> T getAge(T age){
    return age;
 }
}

public class Test2 {
  public static void main(String[] args) {
    MethodGeneric methodGeneric = new MethodGeneric();
    methodGeneric.setName("old");
    Integer age = methodGeneric.getAge(123);
    System.out.println(age);
 }

//无返回值静态方法
public static <泛型标识符号> void setName(泛型标识符号 name){  }
//有返回值静态方法
public static <泛型标识符号> 泛型表示符号getName(泛型标识符号 name){  }

public class MethodGeneric {
  public static <T> void setFlag(T flag){
    System.out.println(flag);
 }
  public static <T> T getFlag(T flag){
    return flag;
 }
}

public class Test4 {
  public static void main(String[] args) {
    MethodGeneric.setFlag("old");
    Integer flag1 =  MethodGeneric.getFlag(123123);
    System.out.println(flag1);
 }
}

public <泛型标识符号> void showMsg(泛型标识符号... agrs){  }

public class MethodGeneric {
  public <T> void method(T...args){
    for(T t:args){
      System.out.println(t);
     }
   }
}
public class Test5 {
  public static void main(String[] args) {
    MethodGeneric methodGeneric = new  MethodGeneric();
    String[] arr = new String[]{"a","b","c"};
    Integer[] arr2 = new Integer[]{1,2,3};
    methodGeneric.method(arr);
    methodGeneric.method(arr2);
  }
}

public void showFlag(Generic<?> generic){  }

public class Generic<T> {
  private T  flag;
  public void setFlag(T flag){
    this.flag = flag;
 }
  public T getFlag(){
    return this.flag;
  }
}
public class ShowMsg {
  public void showFlag(Generic<?> generic){
  System.out.println(generic.getFlag());
 }
}
public class Test3 {
  public static void main(String[] args) {
    ShowMsg showMsg = new ShowMsg();
    Generic<Integer> generic = new  Generic<>();
    generic.setFlag(20);
    showMsg.showFlag(generic);
    Generic<Number> generic1 = new  Generic<>();
    generic1.setFlag(50);
    showMsg.showFlag(generic1);
    Generic<String> generic2 = new Generic<>();
    generic2.setFlag("old");
    showMsg.showFlag(generic2);
 }
}

public void showFlag(Generic<? extends Number> generic){ }

public class ShowMsg {
  public void showFlag(Generic<? extends Number> generic){
        System.out.println(generic.getFlag());
  }
}
public class Test4 {
  public static void main(String[] args) {
    ShowMsg showMsg = new ShowMsg();
    Generic<Integer> generic = new  Generic<>();
    generic.setFlag(20);
    showMsg.showFlag(generic);
    Generic<Number> generic1 = new  Generic<>();
    generic1.setFlag(50);
    showMsg.showFlag(generic1);
 }
}

public void showFlag(Generic<? super Integer> generic){ }

public class ShowMsg {
  public void showFlag(Generic<? super Integer> generic){
     System.out.println(generic.getFlag());
   }
}
public class Test6 {
  public static void main(String[] args) {
    ShowMsg showMsg = new ShowMsg();
    Generic<Integer> generic = new Generic<>();
    generic.setFlag(20);
    showMsg.showFlag(generic);
    Generic<Number> generic1 = new Generic<>();
    generic1.setFlag(50);
    showMsg.showFlag(generic1);
 }
}

public class ArrayListTest {
    public static void main(String[] args) {
        //实例化ArrayList容器
        List<String> list  = new ArrayList<>();
        //添加元素
        boolean flag1 = list.add("oldlu");
        boolean flag2 = list.add("itbz");
        boolean flag3 = list.add("sxt");
        boolean flag4 = list.add("sxt");
        System.out.println(flag1+"\t"+flag2+"\t"+flag3+"\t"+flag4);
        //删除元素
        boolean flag4 = list.remove("oldlu");
        System.out.println(flag4);
        //获取容器中元素的个数
        int size = list.size();
        System.out.println(size);
        //判断容器是否为空
        boolean empty = list.isEmpty();
        System.out.println(empty);
        //容器中是否包含指定的元素
        boolean value = list.contains("itbz");
        System.out.println(value);
        //清空容器
        list.clear();
        Object[] objects1 = list.toArray();
        System.out.println(Arrays.toString(objects1));
   }
}

public class ArrayListTest2 {
    public static void main(String[] args) {
        //实例化容器
        List<String> list = new ArrayList<>();
        //添加元素
        list.add("oldlu");
        list.add("itbz");
        //向指定位置添加元素
        list.add(0,"sxt");
        System.out.println("获取元素");
        String value1 = list.get(0);
        System.out.println(value1);
        System.out.println("获取所有元素方式一");
        //使用普通for循环
        for(int i=0;i<list.size();i++){
            System.out.println(list.get(i));
         }
        System.out.println("获取所有元素方式二");
        //使用Foreach循环
        for(String str:list){
            System.out.println(str);
       }
       System.out.println("元素替换");
        list.set(1,"kevin");
        for(String str:list){
            System.out.println(str);
       }
        System.out.println("根据索引位置删除元素);
        String value2 = list.remove(1);
        System.out.println(value2);
        System.out.println("----------------");
        for(String str:list){
            System.out.println(str);
       }
        System.out.println("查找元素第一次出现的位置");
        int value3 = list.indexOf("sxt");
        System.out.println(value3);
        System.out.println("查找元素最后一次出现的位置");
        list.add("sxt");
        for(String str:list){
            System.out.println(str);
       }
        int value4 = list.lastIndexOf("sxt");
        System.out.println(value4);
   }
}

//并集操作：将另一个容器中的元素添加到当前容器中
        List<String> a  = new ArrayList<>();
        a.add("a");
        a.add("b");
        a.add("c");
        List<String> b = new ArrayList<>();
        b.add("a");
        b.add("b");
        b.add("c");
        //a并集b
        a.addAll(b);
        for(String str :a){
            System.out.println(str);
       }

//交集操作：保留相同的，删除不同的
        List<String> a1  = new ArrayList<>();
        a1.add("a");
        a1.add("b");
        a1.add("c");
        List<String> b1 = new ArrayList<>();
        b1.add("a");
        b1.add("d");
        b1.add("e");
        //交集操作
        a1.retainAll(b1);
        for(String str :a1){
            System.out.println(str);
       }

//差集操作：保留不同的，删除相同的
        List<String> a2  = new ArrayList<>();
        a2.add("a");
        a2.add("b");
        a2.add("c");
        List<String> b2= new ArrayList<>();
        b2.add("b");
        b2.add("c");
        b2.add("d");
        a2.removeAll(b2);
        for(String str :a2){
            System.out.println(str);
       }

/**
* Default initial capacity.
*/
   private static final int DEFAULT_CAPACITY = 10;
/**
* The array buffer into which the elements of the ArrayList are stored.
/**
* The array buffer into which the elements of the ArrayList are stored.
* The capacity of the ArrayList is the length of this array buffer. Any
* empty ArrayList with elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA
* will be expanded to DEFAULT_CAPACITY when the first element is added.
*/
transient Object[] elementData; // nonprivate to simplify nested class access
/**
* The size of the ArrayList (the number of elements it contains).
*
* @serial
*/
private int size;

/**
* Default initial capacity.
*/
private static final int DEFAULT_CAPACITY = 10;

/**
* Appends the specified element to the end of this list.
*
* @param e element to be appended to this list
* @return <tt>true</tt> (as specified by {@link Collection#add})
*/
public boolean add(E e) {
    ensureCapacityInternal(size + 1);  //Increments modCount!!
    elementData[size++] = e;
    return true;
}

//容量检查
private void ensureCapacityInternal(int minCapacity) {  
    ensureExplicitCapacity(calculateCapacity(elementData, minCapacity));
}
//容量确认
private void ensureExplicitCapacity(int minCapacity) {
    modCount++;
    //判断是否需要扩容，数组中的元素个数-数组长度，如果大于0表明需要扩容
    if (minCapacity - elementData.length > 0)
        grow(minCapacity);
}

/**
* Increases the capacity to ensure that it can hold at least the
* number of elements specified by the minimum capacity argument.
*
* @param minCapacity the desired minimum capacity
*/
private void grow(int minCapacity) {
  // overflow-conscious code
    int oldCapacity = elementData.length;
  //扩容1.5倍
    int newCapacity = oldCapacity + (oldCapacity >> 1);
    if (newCapacity - minCapacity < 0)
        newCapacity = minCapacity;
    if (newCapacity - MAX_ARRAY_SIZE > 0)
        newCapacity = hugeCapacity(minCapacity);
    // minCapacity is usually close to size, so this is a win:
    elementData = Arrays.copyOf(elementData,newCapacity);
}

public class VectorTest {
    public static void main(String[] args) {
        //实例化Vector
        List<String> v = new Vector<>();
        v.add("a");
        v.add("b");
        v.add("a");
        for(int i=0;i<v.size();i++){
            System.out.println(v.get(i));
       }
        System.out.println("----------------------");
        for(String str:v){
            System.out.println(str);
       }
   }
}

/**
* The array buffer into which the components of the vector are
* stored. The capacity of the vector is the length of this array buffer,
* and is at least large enough to contain all the vector's elements.
*
* <p>Any array elements following the last element in the Vector are null.
*
* @serial
*/
protected Object[] elementData;
    /**
     * The number of valid components in this {@code Vector} object.
     * Components {@code elementData[0]} through
     * {@code elementData[elementCount-1]} are the actual items.
     *
     * @serial
     */
protected int elementCount;
    /**
     * The amount by which the capacity of the vector is automatically
     * incremented when its size becomes greater than its capacity. If
     * the capacity increment is less than or equal to zero, the capacity
     * of the vector is doubled each time it needs to grow.
     *
     * @serial
     */
protected int capacityIncrement;

public Vector() {
    this(10);
}

/**
* Appends the specified element to the end of this Vector.
*
* @param e element to be appended to this Vector
* @return {@code true} (as specified by {@link Collection#add})
* @since 1.2
*/
public synchronized boolean add(E e) {
    modCount++;
    ensureCapacityHelper(elementCount + 1);
    elementData[elementCount++] = e;
    return true;
}

/**
* This implements the unsynchronized semantics of ensureCapacity.
* Synchronized methods in this class can internally call this
* method for ensuring capacity without incurring the cost of an
* extra synchronization.
*
* @see #ensureCapacity(int)
*/
private void ensureCapacityHelper(int minCapacity) {
    // overflow-conscious code
   //判断是否需要扩容，数组中的元素个数-数组长度，如果大于0表明需要扩容
if (minCapacity - elementData.length >0)
        grow(minCapacity);
}

private void grow(int minCapacity) {
    // overflow-conscious code
    int oldCapacity = elementData.length;
   //扩容2倍
    int newCapacity = oldCapacity + ((capacityIncrement > 0) ? capacityIncrement : oldCapacity);
    if (newCapacity - minCapacity < 0)
        newCapacity = minCapacity;
    if (newCapacity - MAX_ARRAY_SIZE > 0)
        newCapacity = hugeCapacity(minCapacity);
    elementData = Arrays.copyOf(elementData, newCapacity);
}

class  Node<E> {
    Node<E>  previous;   //前一个节点
    E  element;          //本节点保存的数据
    Node<E> next;        //后一个节点
}

public class LinkedListTest {
    public static void main(String[] args) {
        //实例化LinkedList容器
        List<String> list = new LinkedList<>();
        //添加元素
        boolean a = list.add("a");
        boolean b = list.add("b");
        boolean c = list.add("c");
        list.add(3,"a");
        System.out.println(a+"\t"+b+"\t"+c);
        for(int i=0;i<list.size();i++){
            System.out.println(list.get(i));
       }
   }
}

public class LinkedListTest2 {
    public static void main(String[] args) {
        System.out.println("-------LinkedList-------------");
        //将指定元素插入到链表开头
        LinkedList<String> linkedList1 = new LinkedList<>();
        linkedList1.addFirst("a");
        linkedList1.addFirst("b");
        linkedList1.addFirst("c");
        for (String str:linkedList1){
            System.out.println(str);
       }
        System.out.println("----------------------");
        //将指定元素插入到链表结尾
        LinkedList<String> linkedList = new LinkedList<>();
        linkedList.addLast("a");
        linkedList.addLast("b");
        linkedList.addLast("c");
        for (String str:linkedList){
            System.out.println(str);
       }
        System.out.println("---------------------------");
        //返回此链表的第一个元素
        System.out.println(linkedList.getFirst());
        //返回此链表的最后一个元素
        System.out.println(linkedList.getLast());
        System.out.println("-----------------------");
        //移除此链表中的第一个元素，并返回这个元素
        linkedList.removeFirst();
        //移除此链表中的最后一个元素，并返回这个元素
        linkedList.removeLast();
        for (String str:linkedList){
            System.out.println(str);
       }
        System.out.println("-----------------------");
        linkedList.addLast("c");
        //从此链表所表示的堆栈处弹出一个元素,等效于removeFirst
        linkedList.pop();
        for (String str:linkedList){
            System.out.println(str);
       }
        System.out.println("-------------------");
        //将元素推入此链表所表示的堆栈 这个等效于addFisrt(E e)
        linkedList.push("h");
        for (String str:linkedList){
            System.out.println(str);
       }
   }
}

private static class Node<E> {
    E item;
    Node<E> next;
    Node<E> prev;
    Node(Node<E> prev, E element, Node<E> next) {
        this.item = element;
        this.next = next;
        this.prev = prev;
   }
}

transient int size = 0;
/**
* Pointer to first node.
* Invariant: (first == null && last == null) ||
*           (first.prev == null && first.item != null)
*/
transient Node<E> first;
/**
* Pointer to last node.
* Invariant: (first == null && last == null) ||
*            (last.next == null && last.item != null)
*/
transient Node<E> last;

/**
* Appends the specified element to the end of this list.
*
* <p>This method is equivalent to {@link #addLast}.
*
* @param e element to be appended to this list
* @return {@code true} (as specified by {@link Collection#add})
*/
public boolean add(E e) {
    linkLast(e);
    return true;
}
/**
* Links e as last element.
*/
void linkLast(E e) {
    final Node<E> l = last;
    final Node<E> newNode = new Node<>(l, e, null);
    last = newNode;
    if (l == null)
        first = newNode;
    else
        l.next = newNode;
    size++;
    modCount++;
}

/**
* Inserts the specified element at the beginning of this list.
*
* @param e the element to add
*/
public void addFirst(E e) {
    linkFirst(e);
}
/**
* Links e as first element.
*/
private void linkFirst(E e) {
    final Node<E> f = first;
    final Node<E> newNode = new Node<>(null, e, f);
    first = newNode;
    if (f == null)
    last = newNode;
    else
        f.prev = newNode;
    size++;
    modCount++;
}

/**
* Appends the specified element to the end of this list.
*
* <p>This method is equivalent to {@link #add}.
*
* @param e the element to add
*/
public void addLast(E e) {
    linkLast(e);
}
/**
* Links e as last element.
*/
void linkLast(E e) {
    final Node<E> l = last;
    final Node<E> newNode = new Node<>(l, e, null);
    last = newNode;
    if (l == null)
    first = newNode;
    else
        l.next = newNode;
    size++;
    modCount++;
}

/**
* Returns the element at the specified position in this list.
*
* @param index index of the element to return
* @return the element at the specified position in this list
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public E get(int index) {
    checkElementIndex(index);
    return node(index).item;
}

private void checkElementIndex(int index) {
    if (!isElementIndex(index))
        throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}

/**
* Tells if the argument is the index of an existing element.
*/
private boolean isElementIndex(int index) {
    return index >= 0 && index < size;
}

/**
* Returns the (non-null) Node at the specified element index.
*/
Node<E> node(int index) {
    // assert isElementIndex(index);
    if (index < (size >> 1)) {
        Node<E> x = first;
        for (int i = 0; i < index; i++)
            x = x.next;
        return x;
   } else {
        Node<E> x = last;
        for (int i = size - 1; i > index; i--)
            x = x.prev;
            return x;
   }
}

public class HashSetTest {
    public static void main(String[] args) {
        //实例化HashSet
        Set<String> set = new HashSet<>();
        //添加元素
        set.add("a");
        set.add("b1");
        set.add("c2");
        set.add("d");
        set.add("a");
        //获取元素,在Set容器中没有索引，所以没有对应的get(int index)方法
        for(String str: set){
            System.out.println(str);
       }
        System.out.println("--------------------");
        //删除元素
        boolean flag = set.remove("c2");
        System.out.println(flag);
        for(String str: set){
            System.out.println(str);
       }
        System.out.println("------------------------");
        int size = set.size();
        System.out.println(size);
   }
}

public class Users {
    private String username;
    private int userage;
    public Users(String username, int userage) {
    this.username = username;
        this.userage = userage;
   }
    public Users() { }
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Users users = (Users) o;
        if (userage != users.userage) return false;
        return username != null ? username.equals(users.username) : users.username == null;
   }
    @Override
    public int hashCode() {
        int result = username != null ? username.hashCode() : 0;
        result = 31 * result + userage;
        return result;
       }
    public String getUsername() {
        return username;
      }
    public void setUsername(String username)
      {
        this.username = username;
      }
    public int getUserage() {
        return userage;
      }
    public void setUserage(int userage) {
        this.userage = userage;
      }
    @Override
    public String toString() {
        return "Users{" +
                "username='" + username + '\'' +
                ", userage=" + userage +
               '}';
   }
}

public class HashSetTest2 {
    public static void main(String[] args) {
        //实例化HashSet
        Set<Users> set = new HashSet<>();
        Users u = new Users("oldlu",18);
        Users u1 = new Users("oldlu",18);
        set.add(u);
        set.add(u1);
        System.out.println(u.hashCode());
        System.out.println(u1.hashCode());
        for(Users users:set){
            System.out.println(users);
       }
   }
}

private transient HashMap<E,Object> map;
// Dummy value to associate with an Object in the backing Map
private static final Object PRESENT = new Object();

/**
* Adds the specified element to this set if it is not already present.
* More formally, adds the specified element <tt>e</tt> to this set if
* this set contains no element <tt>e2</tt> such that
* <tt>(e==null&nbsp;? &nbsp;e2==null&nbsp;:&nbsp;e.equals(e2)) </tt>.
* If this set already contains the element, the call leaves the set
* unchanged and returns <tt>false</tt>.
*
* @param e element to be added to this set
* @return <tt>true</tt> if this set did not already contain the specified
* element
*/
public boolean add(E e) {
    return map.put(e, PRESENT)==null;
}

public class TreeSetTest {
    public static void main(String[] args) {
        //实例化TreeSet
        Set<String> set = new TreeSet<>();
        //添加元素
        set.add("c");
        set.add("a");
        set.add("d");
        set.add("b");
        set.add("a");
        //获取元素
        for(String str :set){
            System.out.println(str);
       }
   }
}

public class Users implements Comparable<Users>{
    private String username;
    private int userage;
    public Users(String username, intuserage) {
        this.username = username;
        this.userage = userage;
   }
   public Users() { }
  @Override
    public boolean equals(Object o) {
        System.out.println("equals...");
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Users users = (Users) o;
        if (userage != users.userage) return false;
        return username != null ? username.equals(users.username) : users.username == null;
   }
    @Override
    public int hashCode() {
        int result = username != null ? username.hashCode() : 0;
        result = 31 * result + userage;
        return result;
   }
    public String getUsername() {
        return username;
   }
   public void setUsername(String username)
    {
        this.username = username;
   }
   public int getUserage() {
        return userage;
   }
   public void setUserage(int userage) {
        this.userage = userage;
   }
 @Override
  public String toString() {
        return "Users{" +
                "username='" + username + '\'' +
                ", userage=" + userage +
                '}';
   }
    //定义比较规则
    //正数：大，负数：小，0：相等
    @Override
    public int compareTo(Users o) {
        if(this.userage > o.getUserage()){
            return 1;
       }
        if(this.userage == o.getUserage()){
           return this.username.compareTo(o.getUsername());
      }
        return -1;
   }
}

Set<Users> set1 = new TreeSet<>();
Users u = new Users("oldlu",18);
Users u1 = new Users("admin",22);
Users u2 = new Users("sxt",22);
set1.add(u);
set1.add(u1);
set1.add(u2);
for(Users users:set1){
    System.out.println(users);
}

public class Student {
    private String name;
    private int age;
    public Student(String name, int age) {
        this.name = name;
        this.age = age;
   }
    public Student() { }
  @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
   }
    public String getName() {
        return name;
   }
   public void setName(String name) {
        this.name = name;
   }
    public int getAge() {
        return age;
   }
    public void setAge(int age) {
        this.age = age;
   }
    @Override
   public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Student student = (Student) o;
        if (age != student.age) return false;
        return name != null ? name.equals(student.name) : student.name == null;
   }
    @Override
    public int hashCode() {
        int result = name != null ? name.hashCode() : 0;
        result = 31 * result + age;
        return result;
   }
}

public class StudentComparator implements Comparator<Student> {
    //定义比较规则
    @Override
    public int compare(Student o1, Student o2) {
        if(o1.getAge() > o2.getAge()){
            return 1;
       }
        if(o1.getAge() == o2.getAge()){
            return o1.getName().compareTo(o2.getName());
       }
      return -1;
   }
}

public class TreeSetTest3 {
    public static void main(String[] args) {
        //创建TreeSet容器，并给定比较器对象
        Set<Student> set = new TreeSet<>(new StudentComparator());
        Student s = new Student("oldlu",18);
        Student s1 = new Student("admin",22);
        Student s2 = new Student("sxt",22);
        set.add(s);
        set.add(s1);
        set.add(s2);
        for(Student student:set){
            System.out.println(student);
       }
   }
}

/**
* The backing map.
*/
private transient NavigableMap<E,Object> m;
// Dummy value to associate with an Object in the backing Map
private static final Object PRESENT = new Object();

public TreeSet() {
    this(new TreeMap<E,Object>());
}

/**
* Adds the specified element to this set if it is not already present.
* More formally, adds the specified element <tt>e</tt> to this set if
* this set contains no element <tt>e2</tt> such that
* <tt>(e==null&nbsp;? &nbsp;e2==null&nbsp;:&nbsp;e.equals(e2))</tt>.
* If this set already contains the element, the call leaves the set
* unchanged and returns <tt>false</tt>.
*
* @param e element to be added to this set
* @return <tt>true</tt> if this set did not already contain the specified
* element
*/
public boolean add(E e) {
    return map.put(e, PRESENT)==null;
}

public class ListDemo {
    public static void main(String[] args) {
        List<Integer> list = new ArrayList<>();
       while(true){
           //产生随机数
           int num = (int) (Math.random()*10+1);
            //判断当前元素在容器中是否存在
           if(!list.contains(num)){
                list.add(num);
           }
           //结束循环
           if(list.size() == 10){
               break;
           }
       }
       for(Integer i:list){
           System.out.println(i);
       }
   }
}

public class SetDemo {
    public static void main(String[] args) {
        Set<Integer> set = new HashSet<>();
        while(true){
            int num = (int)(Math.random()*10+1);
            //将元素添加容器中，由于Set类型容器是、不允许有重复元素的，所以不需要判断。
            set.add(num);
            //结束循环
            if(set.size() == 10){
                break;
           }
       }
        for(Integer i:set){
            System.out.println(i);
       }
   }
}

public class HashMapTest {
    public static void main(String[] args) {
        //实例化HashMap容器
        Map<String,String> map = new HashMap<>();
        //添加元素
        map.put("a","A");
        map.put("b","B");
        map.put("c","C");
        map.put("a","D");
        //获取容器中元素数量
        int size = map.size();
        System.out.println(size);
        System.out.println("---------------");
        //获取元素
        //方式一
        String v = map.get("a");
        System.out.println(v);
        System.out.println("---------------");
        //方式二
        Set<String> keys = map.keySet();
        for(String key:keys){
            String v1 = map.get(key);
            System.out.println(key+" ----"+v1);
       }
        System.out.println("-------------------");
        //方式三
        Set<Map.Entry<String,String>> entrySet = map.entrySet();
        for(Map.Entry<String,String> entry:entrySet){
            String key = entry.getKey();
            String v2 = entry.getValue();
            System.out.println(key+" ---------- "+v2);
       }
        System.out.println("--------------------");
        //Map容器的并集操作
        Map<String,String> map2 = new HashMap<>();
        map2.put("f","F");
        map2.put("c","CC");
        map.putAll(map2);
        Set<String> keys2 = map.keySet();
        for(String key:keys2){
            System.out.println("key: "+key+" Value: "+map.get(key));
       }
        System.out.println("---------------");
        //删除元素
        String v3 = map.remove("a");
        System.out.println(v3);
        Set<String> keys3 = map.keySet();
        for(String key:keys3){
            System.out.println("key: "+key+" Value: "+map.get(key));
       }
        System.out.println("-------------------");
        //判断Key是否存在
        boolean b = map.containsKey("b");
        System.out.println(b);
        //判断Value是否存在
        boolean cc = map.containsValue("CC");
        System.out.println(cc);
    }
}

/**
* The default initial capacity - MUST be a power of two.
*/
static final int DEFAULT_INITIAL_CAPACITY = 1 << 4; // aka 16
/**
* The maximum capacity, used if a higher value is implicitly specified
* by either of the constructors with arguments.
* MUST be a power of two <= 1<<30.
*/
static final int MAXIMUM_CAPACITY = 1 << 30;
/**
* The load factor used when none specified in constructor.
*/
static final float DEFAULT_LOAD_FACTOR = 0.75f;
/**
* The bin count threshold for using a tree rather than list for a
* bin. Bins are converted to trees when adding an element to a
* bin with at least this many nodes. The value must be greater
* than 2 and should be at least 8 to mesh with assumptions in
* tree removal about conversion back to plain bins upon
* shrinkage.
*/
static final int TREEIFY_THRESHOLD = 8;
/**
* The bin count threshold for untreeifying a (split) bin during a
* resize operation. Should be less than TREEIFY_THRESHOLD, and at
* most 6 to mesh with shrinkage detection under removal.
*/
static final int UNTREEIFY_THRESHOLD = 6;
/**
* The smallest table capacity for which bins may be treeified.
* (Otherwise the table is resized if too many nodes in a bin.)
* Should be at least 4 * TREEIFY_THRESHOLD to avoid conflicts
* between resizing and treeification thresholds.
*/
static final int MIN_TREEIFY_CAPACITY = 64;
/**
* The number of key-value mappings contained in this map.
*/
transient int size;
/**
* The table, initialized on first use, and resized as
* necessary. When allocated, length is always a power of two.
* (We also tolerate length zero in some operations to allow
* bootstrapping mechanics that are currently not needed.)
*/
transient Node<K,V>[] table;

static class Node<K,V> implements
Map.Entry<K,V> {
    final int hash;
    final K key;
    V value;
    Node<K,V> next;
    Node(int hash, K key, V value, Node<K,V> next) {
        this.hash = hash;
        this.key = key;
        this.value = value;
        this.next = next;
   }
public final K getKey()       { return key; }
public final V getValue()     { return value; }
public final String toString() { return key + "=" + value; }
public final int hashCode() { return Objects.hashCode(key) ^ Objects.hashCode(value); }
public final V setValue(V newValue) {
        V oldValue = value;
        value = newValue;
        return oldValue;
   }
public final boolean equals(Object o) {
        if (o == this)
            return true;
        if (o instanceof Map.Entry) {
            Map.Entry<?,?> e = (Map.Entry<?,?>)o;
            if (Objects.equals(key, e.getKey()) && Objects.equals(value, e.getValue()))
                return true;
       }
        return false;
   }
}

/**
* Entry for Tree bins. Extends LinkedHashMap.Entry (which in turn
* extends Node) so can be used as extension of either regular or
* linked node.
*/
static final class TreeNode<K,V> extends LinkedHashMap.Entry<K,V> {
    TreeNode<K,V> parent;  // red-black tree links
    TreeNode<K,V> left;
    TreeNode<K,V> right;
    TreeNode<K,V> prev;    // needed to unlink next upon deletion
    boolean red;
    TreeNode(int hash, K key, V val, Node<K,V> next) {
        super(hash, key, val, next);
   }
    /**
     * Returns root of tree containing thisnode.
     */
    final TreeNode<K,V> root() {
        for (TreeNode<K,V> r = this, p;;) {
            if ((p = r.parent) == null)
                return r;
            r = p;
       }
   }

/**
* Initializes or doubles table size. If null, allocates in
* accord with initial capacity target held in field threshold.
* Otherwise, because we are using power-oftwo expansion, the
* elements from each bin must either stay at same index, or move
* with a power of two offset in the new table.
*
* @return the table
*/
final Node<K,V>[] resize() {
    Node<K,V>[] oldTab = table;
    int oldCap = (oldTab == null) ? 0 : oldTab.length;
    int oldThr = threshold;
    int newCap, newThr = 0;
    if (oldCap > 0) {
        if (oldCap >= MAXIMUM_CAPACITY) {
            threshold = Integer.MAX_VALUE;
            return oldTab;
       }
        else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY &&
                 oldCap >= DEFAULT_INITIAL_CAPACITY)
            newThr = oldThr << 1; // double threshold
   }
    else if (oldThr > 0) // initial capacity was placed in threshold
        newCap = oldThr;
    else {               // zero initialthreshold signifies using defaults
        newCap = DEFAULT_INITIAL_CAPACITY;
        newThr = (int)(DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);
   }
    if (newThr == 0) {
        float ft = (float)newCap * loadFactor;
        newThr = (newCap < MAXIMUM_CAPACITY && ft < (float)MAXIMUM_CAPACITY ?
                 (int)ft : Integer.MAX_VALUE);
   }
    threshold = newThr;
@SuppressWarnings({"rawtypes","unchecked"})
        Node<K,V>[] newTab = (Node<K,V> [])new Node[newCap];
        table = newTab;
    if (oldTab != null) {
        for (int j = 0; j < oldCap; ++j) {
            Node<K,V> e;
            if ((e = oldTab[j]) != null) {
                oldTab[j] = null;
                if (e.next == null)
                    newTab[e.hash & (newCap - 1)] = e;
                else if (e instanceof TreeNode)
            ((TreeNode<K,V>)e).split(this, newTab, j, oldCap);
                else { // preserve order
                    Node<K,V> loHead = null,loTail = null;
                    Node<K,V> hiHead = null,hiTail = null;
                    Node<K,V> next;
                    do {
                        next = e.next;
                        if ((e.hash & oldCap) == 0) {
                            if (loTail ==null)
                                loHead = e;
                            else
                                loTail.next = e;
                            loTail = e;
                       }
                        else {
                            if (hiTail == null)
                                hiHead = e;
                            else
                                hiTail.next = e;
                            hiTail = e;
                       }
                   } while ((e = next) != null);
                    if (loTail != null) {
                        loTail.next = null;
                        newTab[j] = loHead;
                   }
                   if (hiTail != null) {
                        hiTail.next = null;
                        newTab[j + oldCap] = hiHead;
                   }
               }
           }
       }
   }
    return newTab;
}

/**
* Associates the specified value with the specified key in this map.
* If the map previously contained a mapping for the key, the old
* value is replaced.
*
* @param key key with which the specified value is to be associated
* @param value value to be associated with the specified key
* @return the previous value associated with <tt>key</tt>, or
* <tt>null</tt> if there was no mapping for <tt>key</tt>.
*         (A <tt>null</tt> return can also indicate that the map
*         previously associated <tt>null</tt> with <tt>key</tt>.)
*/
public V put(K key, V value) {
    return putVal(hash(key), key, value, false, true);
}
static final int hash(Object key) {
    int h;
    return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
}

/**
* Implements Map.put and related methods
*
* @param hash hash for key
* @param key the key
* @param value the value to put
* @param onlyIfAbsent if true, don't change existing value
* @param evict if false, the table is in creation mode.
* @return previous value, or null if none
*/
final V putVal(int hash, K key, V value,
boolean onlyIfAbsent,
               boolean evict) {
    Node<K,V>[] tab; Node<K,V> p; int n, i;
    if ((tab = table) == null || (n = tab.length) == 0)
        n = (tab = resize()).length;
    if ((p = tab[i = (n - 1) & hash]) == null)
        tab[i] = newNode(hash, key, value, null);
    else {
        Node<K,V> e; K k;
        if (p.hash == hash && ((k = p.key) == key || (key != null && key.equals(k))))
            e = p;
        else if (p instanceof TreeNode)
            e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value);
        else {
            for (int binCount = 0; ; ++binCount) {
                if ((e = p.next) == null) {
                    p.next = newNode(hash, key, value, null);
                    if (binCount >= TREEIFY_THRESHOLD - 1) // -1 for 1st
                        treeifyBin(tab, hash);
                    break;
               }
                if (e.hash == hash &&
                   ((k = e.key) == key || (key != null && key.equals(k))))
                    break;
                p = e;
           }
       }
        if (e != null) { // existing mapping 
       for key
            V oldValue = e.value;
            if (!onlyIfAbsent || oldValue == null)
                e.value = value;afterNodeAccess(e);
            return oldValue;
       }
   }
    ++modCount;
    if (++size > threshold)
        resize();
    afterNodeInsertion(evict);
    return null;
}

/**
* Associates the specified value with the specified key in this map.
* If the map previously contained a mapping for the key, the old
* value is replaced.
*
* @param key key with which the specified value is to be associated
* @param value value to be associated with the specified key
* @return the previous value associated with <tt>key</tt>, or
*         <tt>null</tt> if there was no mapping for <tt>key</tt>.
*         (A <tt>null</tt> return can also indicate that the map
*         previously associated <tt>null</tt> with <tt>key</tt>.)
*/
public V put(K key, V value) {
    return putVal(hash(key), key, value,false, true);
}

/**
* Implements Map.put and related methods
*
* @param hash hash for key
* @param key the key
* @param value the value to put
* @param onlyIfAbsent if true, don't change
existing value
* @param evict if false, the table is in creation mode.
* @return previous value, or null if none
*/
final V putVal(int hash, K key, V value, boolean onlyIfAbsent, boolean evict) {
    Node<K,V>[] tab; Node<K,V> p; int n, i;
    if ((tab = table) == null || (n = tab.length) == 0)
        n = (tab = resize()).length;
    if ((p = tab[i = (n - 1) & hash]) == null)
  tab[i] = newNode(hash, key, value, null);
    else {
        Node<K,V> e; K k;
        if (p.hash == hash &&
           ((k = p.key) == key || (key != null && key.equals(k))))
            e = p;
        else if (p instanceof TreeNode)
            e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value);
        else {
            for (int binCount = 0; ; ++binCount) {
                if ((e = p.next) == null) {
                    p.next = newNode(hash, key, value, null);
                    if (binCount >= TREEIFY_THRESHOLD - 1) // -1 for 1st
                        treeifyBin(tab,hash);
                    break;
               }
                if (e.hash == hash &&
                   ((k = e.key) == key || (key != null && key.equals(k))))
                    break;
                p = e;
           }
       }
if (e != null) { // existing mapping
       for key
            V oldValue = e.value;
            if (!onlyIfAbsent || oldValue == null)
                e.value = value;
            afterNodeAccess(e);
            return oldValue;
       }
   }
    ++modCount;
    if (++size > threshold)
        resize();
    afterNodeInsertion(evict);
    return null;
}

/**
* Initializes or doubles table size. If null, allocates in
* accord with initial capacity target held in field threshold.
* Otherwise, because we are using power-oftwo expansion, the
* elements from each bin must either stay at same index, or move
* with a power of two offset in the new table.
*
* @return the table
*/
final Node<K,V>[] resize() {
     Node<K,V>[] oldTab = table;
    int oldCap = (oldTab == null) ? 0 : oldTab.length;
    int oldThr = threshold;
    int newCap, newThr = 0;
    if (oldCap > 0) {
        if (oldCap >= MAXIMUM_CAPACITY) {
            threshold = Integer.MAX_VALUE;
            return oldTab;
       }
        else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY &&
                 oldCap >= DEFAULT_INITIAL_CAPACITY)
            newThr = oldThr << 1; // double threshold
   }
    else if (oldThr > 0) // initial capacity
        was placed in threshold
        newCap = oldThr;
    else {               // zero initial threshold signifies using defaults
        newCap = DEFAULT_INITIAL_CAPACITY;
        newThr = (int)(DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);
   }
    if (newThr == 0) {
        float ft = (float)newCap * loadFactor;
        newThr = (newCap < MAXIMUM_CAPACITY && ft < (float)MAXIMUM_CAPACITY ?
        (int)ft : Integer.MAX_VALUE);
   }
    threshold = newThr;
@SuppressWarnings({"rawtypes","unchecked"})
        Node<K,V>[] newTab = (Node<K,V> [])new Node[newCap];
        table = newTab;
    if (oldTab != null) {
        for (int j = 0; j < oldCap; ++j) {
            Node<K,V> e;
            if ((e = oldTab[j]) != null) {
                oldTab[j] = null;
                if (e.next == null)
                    newTab[e.hash & (newCap - 1)] = e;
                else if (e instanceof TreeNode)
                 ((TreeNode<K,V>)e).split(this, newTab, j, oldCap);
                else { // preserve order
                    Node<K,V> loHead = null, loTail = null;
                    Node<K,V> hiHead = null, hiTail = null;
                    Node<K,V> next;
                    do {
                        next = e.next;
                        if ((e.hash & oldCap) == 0) {
                          if (loTail == null)
                                loHead = e;
                            else
                                loTail.next = e;
                            loTail = e;
                       }
                        else {
                            if (hiTail == null)
                                hiHead = e;
                            else
                                hiTail.next = e;
                            hiTail = e;
                       }
                   } while ((e = next) != null);
                    if (loTail != null) {
                        loTail.next = null;
                        newTab[j] = loHead;
                   }
                    if (hiTail != null) {
                        hiTail.next = null;
                        newTab[j + oldCap] = hiHead;
                   }
               }
           }
       }
   }
 return newTab;
}

public class Users implements
Comparable<Users>{
    private String username;
    private int userage;
public Users(String username, int userage) {
        this.username = username;
        this.userage = userage;
   }
    public Users() { }
    @Override
    public boolean equals(Object o) {
        System.out.println("equals...");
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Users users = (Users) o;
        if (userage != users.userage) return false;
        return username != null ? username.equals(users.username) : users.username == null;
   }
    @Override
    public int hashCode() {
        int result = username != null ? username.hashCode() : 0;
        result = 31 * result + userage;
        return result;
}
    public String getUsername() {
        return username;
   }
    public void setUsername(String username)
     {
        this.username = username;
     }
    public int getUserage() {
        return userage;
     }
    public void setUserage(int userage) {
        this.userage = userage;
   }
    @Override
    public String toString() {
        return "Users{" +
                "username='" + username + '\'' +
                ", userage=" + userage +
                '}';
   }
    //定义比较规则
    //正数：大，负数：小，0：相等
    @Override
    public int compareTo(Users o) {
       if(this.userage < o.getUserage()){
            return 1;
       }
        if(this.userage == o.getUserage()){
           return this.username.compareTo(o.getUsername());
       }
        return -1;
   }
}

public class TreeMapTest {
    public static void main(String[] args) {
        //实例化TreeMap
        Map<Users,String> map = new TreeMap<>();
        Users u1 = new Users("oldlu",18);
        Users u2 = new Users("admin",22);
        Users u3 = new Users("sxt",22);
        map.put(u1,"oldlu");
        map.put(u2,"admin");
        map.put(u3,"sxt");
        Set<Users> keys = map.keySet();
        for(Users key :keys){
            System.out.println(key+" --------- "+map.get(key));
       }
   }
}

public class Student {
    private String name;
    private int age;
    public Student(String name, int age) {
        this.name = name;
        this.age = age;
   }
    public Student() { }
    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
   }
    public String getName() {
        return name;
   }
    public void setName(String name) {
        this.name = name;
   }
    public int getAge() {
        return age;
   }
  public void setAge(int age) {
        this.age = age;
   }
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Student student = (Student) o;
        if (age != student.age) return false;
        return name != null ? name.equals(student.name) : student.name == null;
   }
    @Override
    public int hashCode() {
        int result = name != null ? name.hashCode() : 0;
        result = 31 * result + age;
        return result;
   }
}

public class StudentComparator implements Comparator<Student> {
    //定义比较规则
  @Override
    public int compare(Student o1, Student o2) {
        if(o1.getAge() > o2.getAge()){
            return 1;
       }
        if(o1.getAge() == o2.getAge()){
            return
           o1.getName().compareTo(o2.getName());
       }
        return -1;
   }
}

public class TreeMapTest {
    public static void main(String[] args) {
          Map<Student,String> treeMap = new TreeMap<>(new StudentComparator());
    Student s1 = new Student("oldlu",18);
    Student s2 = new Student("admin",22);
    Student s3 = new Student("sxt",22);
    treeMap.put(s1,"oldlu");
    treeMap.put(s2,"admin");
    treeMap.put(s3,"sxt");
    Set<Student> keys1 = treeMap.keySet();
    for(Student key :keys1){
        System.out.println(key+" ----"+treeMap.get(key));
     }
   }
}

private transient Entry<K,V> root = null;

public class IteratorListTest {
    public static void main(String[] args) {
        //实例化容器
        List<String> list  = new ArrayList<>();
        list.add("a");
        list.add("b");
        list.add("c");
        //获取元素
        //获取迭代器对象
        Iterator<String> iterator = list.iterator();
        //方式一:在迭代器中，通过while循环获取元素
        while(iterator.hasNext()){
            String value = iterator.next();
            System.out.println(value);
       }
        System.out.println("-------------------------------");
        //方法二：在迭代器中，通过for循环获取元素
        for(Iterator<String> it = list.iterator();it.hasNext();){
            String value = it.next();
            System.out.println(value);
       }
   }
}

public class IteratorSetTest {
    public static void main(String[] args) {
        //实例化Set类型的容器
        Set<String> set  = new HashSet<>();
        set.add("a");
        set.add("b");
        set.add("c");
        //方式一：通过while循环
        //获取迭代器对象
        Iterator<String> iterator = set.iterator();
        while(iterator.hasNext()){
            String value = iterator.next();
            System.out.println(value);
           }
        System.out.println("-------------------------");
        //方式二：通过for循环
        for(Iterator<String> it = set.iterator();it.hasNext();){
            String value = it.next();
            System.out.println(value);
       }
   }
}

public class IteratorMapTest {
    public static void main(String[] args) {
        //实例化HashMap容器
        Map<String, String> map = new HashMap<String, String>();
        //添加元素
        map.put("a", "A");
        map.put("b", "B");
        map.put("c", "C");
        //遍历Map容器方式一
        Set<String> keySet = map.keySet();
        for (Iterator<String> it = keySet.iterator(); it.hasNext();){
            String key = it.next();
            String value = map.get(key);
            System.out.println(key+" ------------- "+value);
       }
        System.out.println("------------------------");
        //遍历Map容器方式二
        Set<Map.Entry<String, String>> entrySet = map.entrySet();
        Iterator<Map.Entry<String, String>> iterator = entrySet.iterator();
        while(iterator.hasNext()){
            Map.Entry entry = iterator.next();
         System.out.println(entry.getKey()+" ------------ "+ entry.getValue());
       }
   }
}

public class IteratorRemoveTest {
    public static void main(String[] args) {
        List<String> list = new ArrayList<>();
        list.add("a");
        list.add("b");
        list.add("c");
        list.add("d");
        Iterator<String> iterator = list.iterator();
        while(iterator.hasNext()){
            //不要在一次循环中多次调用next方法。
            String value = iterator.next();
            iterator.remove();
       }
        System.out.println("----------------");
        for(Iterator<String> it = list.iterator();
           it.hasNext();){
            System.out.println(it.next());
            list.add("dddd");
       }
   }
}

for(int i=0;i<list.size();i++){//list为集合的对象名
 String temp = (String)list.get(i);
 System.out.println(temp);
}

for (String temp : list) {
 System.out.println(temp);
}

for(Iterator iter=
list.iterator();iter.hasNext();){
 String temp = (String)iter.next();
 System.out.println(temp);
}

Iterator  iter =list.iterator();
while(iter.hasNext()){
 Object  obj =  iter.next();
 iter.remove();//如果要遍历时，删除集合中的元素，建议使用这种方式！
 System.out.println(obj);
}

for(String temp:set){
 System.out.println(temp);
}

for(Iterator iter =
set.iterator();iter.hasNext();){
 String temp = (String)iter.next();
 System.out.println(temp);
}

Map<Integer, Man> maps = new HashMap<Integer,
Man>();
Set<Integer>  keySet =  maps.keySet();
for(Integer id : keySet){
 System.out.println(maps.get(id).name);
}

Set<Map.Entry<Integer, Man>>  ss =
maps.entrySet();
for (Iterator<Map.Entry<Integer, Man>>
iterator = ss.iterator();
iterator.hasNext();) {
 Map.Entry e =  iterator.next();
 System.out.println(e.getKey()+"--
"+e.getValue());
}

public class CollectionsTest {
    public static void main(String[] args) {
        List<String> list = new ArrayList<>();
        list.add("c");
        list.add("b");
        list.add("a");
        //对元素排序
        Collections.sort(list);
        for(String str:list){
            System.out.println(str);
       }
        System.out.println("-------------------");
        List<Users> list2 = new ArrayList<>();
        Users u = new Users("oldlu",18);
        Users u2 = new Users("sxt",22);
        Users u3 = new Users("admin",22);
        list2.add(u);
        list2.add(u2);
        list2.add(u3);
        //对元素排序
        Collections.sort(list2);
        for(Users user:list2){
            System.out.println(user);
       }
        System.out.println("-------------------");
        List<Student> list3 = new ArrayList<>();
        Student s = new Student("oldlu",18);
        Student s1 = new Student("sxt",20);
        Student s2 = new Student("admin",20);
        list3.add(s);
        list3.add(s1);
        list3.add(s2);
        Collections.sort(list3,new StudentComparator());
        for(Student student:list3){
            System.out.println(student);
       }
        System.out.println("-------------------");
        List<String> list4 = new ArrayList<>();
        list4.add("a");
        list4.add("b");
        list4.add("c");
        list4.add("d");
        //洗牌
        Collections.shuffle(list4);
        for(String str:list4){
            System.out.println(str);
       }
   }
}