package package1;import java.util.ArrayList;import java.util.Iterator;import java.util.List;public class Demo3 {	public static void main(String[] args) {		List
    
      all=new ArrayList
     
      ();		//hashset无序但不允许重复,treeset不允许重复		all.add("a");		all.add("b");		all.add("c");		all.add(2,"d");//把d插入下标为2的位置		all.set(0, "hello");//把下标元素为0的值替换为hello		//System.out.println(all);		System.out.println("使用迭代法");		Iterator
      
        it=all.iterator();		while(it.hasNext()) {		String name=it.next();		System.out.println(name);		}		System.out.println("使用增强for循环");		for(String name:all) {			System.out.println(name);		}		System.out.println("**************");		//判断是否有lisi这个值，有则返回所对应的索引，没有则返回-1;		System.out.println(all.lastIndexOf("lisi"));		System.out.println(all.remove("hello"));//移除hello		System.out.println(all.remove(0));//移除下标为0的值			System.out.println("=======");		System.out.println(all.size());//集合返回个数		System.out.println(all.contains("hello"));//是否包含hello		System.out.println(all.get(0));//获取下标为0的值		System.out.println(all.isEmpty());//清除前		all.clear();//清除		System.out.println(all.isEmpty());//清除后	}}实例：package package1;import java.util.ArrayList;import java.util.List;public class Demo4 {public static void main(String[] args) {	List
       
         list=new ArrayList<>();	Student student1=new Student("zhangsan", 20);	Student student2=new Student("zl", 20);	Student student3=new Student("wangwu", 20);	Student student4=new Student("lisi", 20);	list.add(student1);	list.add(student2);	list.add(student3);	list.add(student4);	for(Student stu:list) {		System.out.println("姓名："+stu.getName()+"年龄："+stu.getAge());	}}}class Student{	String name;	int age;	public Student(String name,int age) {		this.name=name;		this.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;	}}遍历List集合的三种方法List
        
          list = new ArrayList
         
          ();list.add("aaa");list.add("bbb");list.add("ccc");方法一：超级for循环遍历for(String attribute : list) { System.out.println(attribute);}方法二：对于ArrayList来说速度比较快, 用for循环, 以size为条件遍历:for(int i = 0 ; i < list.size() ; i++) { system.out.println(list.get(i));}方法三：集合类的通用遍历方式, 从很早的版本就有, 用迭代器迭代Iterator it = list.iterator();while(it.hasNext()) { System.ou.println(it.next);}练习：package package1;import java.util.ArrayList;public class Demo9 { public static void main(String [] args) { String[] array ={"小王，男，1980-03-08","小zhang，男，1980-03-08","小ma，男，1980-03-08"}; ArrayList
          
            list = new ArrayList
           
            (); System.out.println("原集合"); for(int i=0;i