ArrayList动态数组的基本方法

Posted 2021-01-14 gc56-db

package com.wy.test;

import com.sun.org.apache.xpath.internal.operations.Bool;
/*动态数组基本方法*/

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

public class ArraylistTest {
    public static void main(String[] args) {
     List<String> list = new ArrayList();

        //1.增加元素
        list.add("china");
        list.add("USA");
        list.add("Japen");
        list.add("Australia");
        System.out.println(list);
        list.add(2,"Germany");
        System.out.println(list);
        System.out.println("--------------------");

        //2.修改元素
        list.set(1,"France");
        System.out.println(list);
        System.out.println("--------------------");

        //3.查找元素
        int a = list.indexOf("Japen");
        String b = list.get(2);
        System.out.println(b);
        System.out.println(a);
        System.out.println("--------------------");

        //4.删除元素
        list.remove(3);
        System.out.println(list);
        System.out.println("--------------------");

        //5.数组长度
        int x = list.size();
        System.out.println(x);
        System.out.println("---------------------");

        //6.判断数组是否为空
        boolean y = list.isEmpty();
        System.out.println(y);

       

    }
}

输出结果

[china, USA, Japen, Australia]
[china, USA, Germany, Japen, Australia]
--------------------
[china, France, Germany, Japen, Australia]
--------------------
Germany
3
--------------------
[china, France, Germany, Australia]
--------------------
4
---------------------
false

Process finished with exit code 0