List接口

List接口性质

import java.util.ArrayList;
import java.util.List;

public class List_ {
    public static void main(String[] args) {
        //1.List集合类中元素有序（即添加顺序合取出顺序一致），且可重复
        List list = new ArrayList();
        list.add("jack");
        list.add("tom");
        list.add("mary");
        list.add("hsp");
        list.add("tom");
        System.out.println("list="+list);
        //2.LIST集合中的每个元素都有其对应的顺序索引，即支持索引
        //索引是从0开始的
        System.out.println(list.get(3));

    }
}

======================

常用List方法

import java.util.ArrayList;
import java.util.List;

public class ListMethod {
    public static void main(String[] args) {
       List list = new ArrayList();
       list.add("张三丰");
       list.add("贾宝玉");
       //void add(int index，Object ele)在index位置插入ele元素
        list.add(1,"abc");
        System.out.println("list="+list);
        //addALL()加所有元素
        List list2 = new ArrayList();
        list2.add("jack");
        list2.add("tom");
        list.addAll(1,list2);
        System.out.println(list);
        //get()获取指定位置元素
        //indexOf()返回集合中首次出现的位置
        System.out.println(list.indexOf("tom"));
        //lastIndexOf()最后出现的位置
        list.add("tom");
        System.out.println(list.lastIndexOf("tom"));
        //REMOVE 移除指定位置
        list.remove(0);
        System.out.println(list);
        //set设置index位置的元素，相当于替换
        list.set(1, "WWW");
        System.out.println(list);
        //subList返回从fromIndex到toIndex位置的子集合
        // 返回的子集合前闭后开 fromIndex<=subList<toIndex
        List list1 = list.subList(0, 2);
        System.out.println(list1);


    }

=========================================

List接口三种基本遍历

1.迭代器Iterator

2.增强for

3.基本for

======================================

冒泡排序List集合

import java.util.ArrayList;
import java.util.List;

public class ListExercise {
    public static void main(String[] args) {
        List list = new ArrayList();
        list.add(new Book("三国志", "罗贯中", 30));
        list.add(new Book("红楼梦", "曹雪芹", 31));
        list.add(new Book("西游记", "吴承恩", 32));



        //遍历
        for (Object o : list) {
            System.out.println(o);
        }
        System.out.println("=================");

        //如何对集合进行排序 :冒泡排序
        sort(list);
        for (Object o : list) {
            System.out.println(o);
        }


    }
    //静态方法
    //价格要求从小到大
    public static void sort(List list){
        int size=list.size();
        for (int i = 0; i < size-1; i++) {
            for (int j = 0; j <size-1-i ; j++) {
             // 取出对象Book
                Book book1=(Book)list.get(j);
                Book book2=(Book)list.get(j+1);
                if (book1.getPrice()>book2.getPrice()){
                    //交换
                    list.set(j,book2);
                    list.set(j+1,book1);
                }


            }
        }
    }
}
class Book{
    private String name;
    private String author;
    private double price;
    public Book(String name, String author, double price) {
        this.name = name;
        this.author = author;
        this.price = price;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "名称："+name+"\t\t价格："+price+"\t\t作者："+author;
    }
}

1