集合框架-list集合

集合本身就是一个容器，容器的特点，就是对存储的元素进行增删改查（增删改查）

增加删除快，修改查询慢

增加删除慢，修改查询快

堆栈：先进后出(存储数据从上往下先存储，打印的时候后面的先打印)
队列：先进先出(存储数据从上往下先存储，打印的时候前面的先打印)

for (int i = 0; i < list.size(); i++) {
    System.out.println(list.get(i));
  }

for (Object object : list) {
    System.out.println(object);
  }

Iterator iterator = list.iterator();
  while(iterator.hasNext()) {
    System.out.println(iterator.next());
  }

当Arraylist集合存储的长度已满时，再次添加数据时，集合的长度会扩增为1.5倍，增长因子为0.5

package com.yuan.List;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
public class list {
public static void main(String[] args) {
  List list = new ArrayList<>();
  list.add(new Student(1, "1"));
  list.add(new Student(2, "2"));
  list.add(new Student(3, "3"));
  list.add(new Student(3, "3"));
  List newlist = new ArrayList<>();
  for (Object object : list) {
    if(!newlist.contains(object)) {
      newlist.add(object);
    }
  }
  System.out.println(list.size());
  System.out.println(newlist.size());
}
}
class Student{
  private int id;
  private String name;
  public Student() {
    // TODO Auto-generated constructor stub
  }
  public Student(int id, String name) {
    super();
    this.id = id;
    this.name = name;
  }
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
  @Override
  public String toString() {
    return "student [id=" + id + ", name=" + name + "]";
  }
  @Override
  public boolean equals(Object obj) {
    if (this == obj)
      return true;
    if (obj == null)
      return false;
    if (getClass() != obj.getClass())
      return false;
    Student other = (Student) obj;
    if (id != other.id)
      return false;
    if (name == null) {
      if (other.name != null)
        return false;
    } else if (!name.equals(other.name))
      return false;
    return true;
  }
}