Java容器小结和使用示例

import java.lang.String;
import java.util.*;

public class JAVAContainer {

    // Interfaces:
    // Interface Iterator: hasNext(),  next(), remove() ---- 所有容器通用的遍历方式。
    // Interface Collection：add(E e)，remove(Object o), clear(), isEmpty(), size(), iterator(), toArray() ---- 所有单值容器(map除外)的公共接口。 
    // Interface Map: put(K key, V value), get(Object key), remove(Object key), clear()，isEmpty()，size(), keySet(), entrySet(), values()  ---- 所有K-V容器的公共接口，常见class: HashMap, Hashtable, IdentityHashMap, LinkedHashMap, ConcurrentHashMap
    // Interface Map.Entry: getKey(), getValue(), setValue(V value) ---- 用于遍历Map容器。
    //

    public static void main(String[] args) throws Exception {
        // ArrayList
        {
            ArrayList arraylist = new ArrayList();
            arraylist.add(0, "end");//指定索引加入值
            // 需注意的是，如果现有2个值，我加入索引为5的那么就会出现异常
            for (int i = 0; i < 2; i++) {
                arraylist.add(i, String.valueOf(i));
            }
            System.out.println("ArrayList:");
            for (int i = 0; i < arraylist.size(); i++) {
                System.out.print(arraylist.get(i) + ";");
            }

            arraylist.add("0");//直接加入值到ArrayList的最后
            arraylist.add("0");
            System.out.println("");
            System.out.print(" ArrayList's lastIndexOf(\"0\") is " + arraylist.lastIndexOf("0")); 

            for (Object val : arraylist) {
                System.out.print( val + ";");
            }
            System.out.println("\n");
        }

        // Arrays
        {
            String[] array = new String[] { "a", "b", "c" };
            List list = Arrays.asList(array);
            System.out.println(" Arrays:");
            for (int i = 0; i < list.size(); i++) {
                System.out.print(list.get(i) + ";");
            }
            System.out.print(" Arrays's length is " + array.length);//打印数组的长度
            
            System.out.println("");
            for (Object val : array) {
                System.out.print( val + ";");
            }
            System.out.println("\n");
        }

        // Collections
        {
            String[] array = new String[] { "a", "b", "c" };
            List list = Arrays.asList(array);
            Collections.fill(list, "Fill");//用Fill填充全部元素
            System.out.println(" Collections:");
            for (int i = 0; i < list.size(); i++) {
                System.out.print(list.get(i) + ";");
            }
            array = new String[] { "1", "2", "3" };
            List list2 = Arrays.asList(array);
            Collections.copy(list, list2);//拷贝list2的数据进list
            System.out.println(" " + list);
            Collections.swap(list, 2, 1);//调换索引为1和2的元素的位置
            System.out.println(list);
            System.out.println("\n");
        }

        // EventObject
        {
            String s = "hello";
            String s2 = s;
            EventObject eventobject = new EventObject(s);//一个准容器类型，确切的归类它不是容器
            System.out.println("EventObject:");
            System.out.println(eventobject.getSource());
            System.out.println(eventobject.equals(s2));
            System.out.println("\n");
        }

        // HashMap
        {
            HashMap hashmap = new HashMap();//一个速度最快的容器
            hashmap.put("0", "c");
            hashmap.put("1", "a");
            hashmap.put("2", "b");
            hashmap.put("3", "a");

            System.out.println("HashMap:");
            System.out.println(hashmap);//该容器有其内部的排序方式
            Set set = hashmap.keySet();//获取全部键
            Iterator iterator = set.iterator();
            while (iterator.hasNext()) {
                System.out.print(hashmap.get(iterator.next()) + ";");
            }
            System.out.println("");

            System.out.println("HashMap: K-V");
            iterator = set.iterator();
            while (iterator.hasNext()) {
                Object key = iterator.next();
                System.out.print(key+":"+hashmap.get(key) + ";");
            }
            System.out.println("");

            System.out.println("HashMap(Entry): K-V");
            Set<Map.Entry> kvSet = hashmap.entrySet();
            Iterator<Map.Entry> it = kvSet.iterator();
            while (it.hasNext()){
                Map.Entry entry = it.next();
                System.out.print( entry.getKey()+":" + entry.getValue() +";");
            } 

            System.out.println("\n");
        }

        // HashSet
        {
            HashSet hashset = new HashSet();//一个绝对不能重复的类型
            hashset.add("c");
            hashset.add("b");
            hashset.add("a");
            hashset.add("a");
            hashset.add("b");
            System.out.println(" HashSet:");
            System.out.println(hashset);
            Iterator iterator = hashset.iterator();//取出元素
            while (iterator.hasNext()) {
                System.out.print(iterator.next() + ";");
            }
            System.out.println("\n");
        }

        // Hashtable
        {
            Hashtable hashtable = new Hashtable();//一个完全可以由其他容器替换的老容器类型
            hashtable.put("0", "c");
            hashtable.put("1", "a");
            hashtable.put("3", "c");
            hashtable.put("2", "b");
            System.out.println(" Hashtable:");
            Enumeration enumeration = hashtable.elements();//获取元素，Enumeration已经不是主流，Iterator是它的下一代替代品
            while (enumeration.hasMoreElements()) {
                System.out.print(enumeration.nextElement() + ";");
            }
            System.out.println("\n");
        }

        // IdentityHashMap
        {
            IdentityHashMap identityhashmap = new IdentityHashMap();
            identityhashmap.put("0", "c");
            identityhashmap.put("1", "a");
            identityhashmap.put("3", "b");
            identityhashmap.put("2", "a");
            System.out.println(" IdentityHashMap:");
            System.out.println(identityhashmap);
            System.out.println(identityhashmap.containsKey("3"));//是否包含这个键
            System.out.println(identityhashmap.containsValue("a"));//是否包含值
            Set set = identityhashmap.entrySet();//传为Set类型
            System.out.println(set);
            set = identityhashmap.keySet();//全部键
            System.out.println(set);
            System.out.println("\n");
        }

        // LinkedHashMap
        {
            LinkedHashMap linkedhashmap = new LinkedHashMap();
            linkedhashmap.put("0", "b");
            linkedhashmap.put("2", "a");
            linkedhashmap.put("1", "c");
            linkedhashmap.put("3", "b");
            System.out.println("LinkedHashMap:");
            System.out.println(linkedhashmap);
            System.out.println(linkedhashmap.containsKey("2"));//是否包含这个键
            System.out.println(linkedhashmap.containsValue("c"));//是否包含值
            Set set = linkedhashmap.keySet();
            Iterator iterator = set.iterator();
            while (iterator.hasNext()) {
                System.out.print(linkedhashmap.get(iterator.next()) + ";");
            }
            System.out.println("\n");
        }

        // LinkedHashSet
        {
            LinkedHashSet linkedhashset = new LinkedHashSet();//它包含了几种Set的属性但却没有自己的特色
            linkedhashset.add("c");
            linkedhashset.add("a");
            linkedhashset.add("a");
            linkedhashset.add("b");
            System.out.println(" LinkedHashSet:");
            System.out.println(linkedhashset);
            System.out.println(linkedhashset.contains("a"));//是否包含对象
            Iterator iterator = linkedhashset.iterator();
            while (iterator.hasNext()) {
                System.out.print(iterator.next() + ";");
            }
            System.out.println("\n");
        }

        // LinkedList
        {
            LinkedList linkedlist = new LinkedList();//自由使用是它的特色
            linkedlist.add("a");
            linkedlist.add(1, "c");
            linkedlist.addLast("b");
            linkedlist.addFirst("d");
            System.out.println(" LinkedList:");
            System.out.println(linkedlist);
            // linkedlist.clear();//该方法清空容器
            // linkedlist.remove(0);//删除索引为0的元素
            // linkedlist.remove("d");//删除值为d的元素
            // linkedlist.removeFirst();//删除第一个元素
            // linkedlist.removeLast();//删除最后一个元素
            for (int i = 0; i < linkedlist.size(); i++) {
                System.out.print(linkedlist.get(i) + ";");
            }
            System.out.println("\n");
        }

        // Stack
        {
            Stack stack = new Stack();//堆栈
            stack.add("b");
            stack.add(0, "c");
            stack.push("d");
            stack.add("e");
            stack.push("a");
            Enumeration enumeration = stack.elements();
            System.out.println(" Stack:");
            while (enumeration.hasMoreElements()) {
                System.out.print(enumeration.nextElement() + ";");
            }
            // 后进先出
            System.out.println(" " + stack.peek());
            System.out.println(stack.pop());
            System.out.println(stack.contains("d") + ";" + stack.contains("a"));//是否包含该元素,有趣的事情发生了
            System.out.println(stack.search("c"));//非常有用的属性，检索，但是由后向前的排列
            System.out.println("\n");
        }

        // TreeMap
        {
            TreeMap treemap = new TreeMap();
            treemap.put("0", "d");
            treemap.put("2", "a");
            treemap.put("1", "b");
            treemap.put("3", "c");
            System.out.println(" TreeMap:");//可以对键排序
            System.out.println(treemap);
            System.out.println(treemap.firstKey());//返回第一个键
            Set set = treemap.keySet();
            Iterator iterator = set.iterator();
            while (iterator.hasNext()) {
                System.out.print(treemap.get(iterator.next()) + ";");
            }
            System.out.println("\n");
        }

        // TreeSet
        {
            TreeSet treeset = new TreeSet();//自动排序内容
            treeset.add("b");
            treeset.add("a");
            treeset.add("c");
            treeset.add("d");
            System.out.println(" TreeSet:");
            System.out.println(treeset);
            System.out.println(treeset.first());//返回第一个元素
            Iterator iterator = treeset.iterator();
            while (iterator.hasNext()) {
                System.out.print(iterator.next() + ";");
            }
            System.out.println("\n");
        }

        // Vector
        {
            Vector vector = new Vector();
            vector.add(0, "b");
            vector.add("a");
            vector.addElement("d");
            vector.add("c");
            System.out.println(" Vector:");
            System.out.println(vector);
            vector.set(2, "h");//替换掉指定索引的元素
            System.out.println(vector);
            Object[] str = vector.toArray();
            for (int i = 0; i < str.length; i++) {
                System.out.print(str[i] + ";");
            }
            vector.setSize(2);//重新设置大小为2
            System.out.println(" " + vector);
            System.out.println("\n");
        }

        // WeakHashMap
        {
            WeakHashMap weakhashmap = new WeakHashMap();
            weakhashmap.put("1", "b");
            weakhashmap.put("2", "c");
            weakhashmap.put("0", "d");
            weakhashmap.put("3", "a");
            System.out.println(" WeakHashMap:");
            System.out.println(weakhashmap);
            System.out.println(weakhashmap.containsKey("3"));//是否包含键
            System.out.println(weakhashmap.containsValue("d"));//是否包含值
            Set set = weakhashmap.entrySet();
            Iterator iterator = set.iterator();
            while (iterator.hasNext()) {
                System.out.print(iterator.next() + ";");
            }
            // weakhashmap.remove("2");//删除该键对应的值
            // weakhashmap.get("1");//获取指定键的值
            System.out.println("\n");
        }
    }
}

本文转自 zhenjing 博客园博客，原文链接：http://www.cnblogs.com/zhenjing/archive/2013/04/25/java_Container.html   ，如需转载请自行联系原作者