JAVA#List'学习札记

1.List集合类中元素有序且可重复。其常用实现类有：ArrayList，LinkedList和Vector。

2.  e.g.

public class Lister {
    @Test
    public void MM(){
        List list=new ArrayList();
        list.add(3);
        list.add(24);
        list.add(24);
        list.add(23);
        list.add(new String("Kobe"));
        list.add(new String("Iverson"));
        list.add(3);
        System.out.println(list);
        System.out.println("$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");

        //void add(int index,Object element)   在指定的索引位置index添加元素element
        list.add(0, new String("宋小艾"));
        System.out.println(list);
        System.out.println("$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");
        // Object get(int index)   获取指定索引位置的元素
        System.out.println(list.get(1));
        System.out.println(list);
        System.out.println("$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");

        //Object remove(int index)  删除指定索引的元素
        list.remove(1);
        System.out.println(list);
        System.out.println("$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");

        // Object set(int index,Object element)   设置指定索引的元素为element
        list.set(1, new String("宋小艾王牌天神"));
        System.out.println(list);
        System.out.println("$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");

        // int indexOf(Object obj)  返回obj在集合中首次出现的位置，没有的话返回-1；
        System.out.println(list.indexOf(3));
        System.out.println(list.indexOf(3222));
        System.out.println("$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");

        // int lastIndexOf(Object obj)   返回obj在集合中最后一次出现的位置，没有的话返回-1；
        list.add(3);
        System.out.println(list.lastIndexOf(3));
        System.out.println(list.lastIndexOf(33443));
        System.out.println("$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");

        //List subList(int fromIndex, int toIndex)  返回左闭右开的一个list
        System.out.println(list.subList(1,3));
    }
}

[3, 24, 24, 23, Kobe, Iverson, 3]
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
[宋小艾, 3, 24, 24, 23, Kobe, Iverson, 3]
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
3
[宋小艾, 3, 24, 24, 23, Kobe, Iverson, 3]
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
[宋小艾, 24, 24, 23, Kobe, Iverson, 3]
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
[宋小艾, 宋小艾王牌天神, 24, 23, Kobe, Iverson, 3]
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
6
-1
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
7
-1
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
[宋小艾王牌天神, 24]