ArrayList常用方法

ArrayList 类是一个可以动态修改的数组，与普通数组的区别就是它是没有固定大小的限制，我们可以添加或删除元素。

ArrayList 继承了 AbstractList ，并实现了 List 接口。

一、添加元素

ArrayList 类提供了很多有用的方法，添加元素到 ArrayList 可以使用 add() 方法

代码如下：

public class testList {public static void main(String[] args) {//创建ArrayList对象，泛型为String类型ArrayList<String> list = new ArrayList<>();//添加元素list.add("添");list.add("加");list.add("元");list.add("素");System.out.println(list);}
}

运行结果：

[添, 加, 元, 素]

二、完成随机抽取一个名字

知道了如何使用ArrayList添加，那么结合Scanner类和Random类完成随机抽取一个名字

1.使用Arrays.aslist录入内容

public static void main(String[] args) {List<String> list = Arrays.asList("佐菲","初代","赛文","杰克","艾斯","泰罗","奥特之父","奥特之母","雷欧","阿斯特拉","奥特之王","乔尼亚斯"," 爱迪"," 史考特"," 查克"," 贝斯"," 葛雷"," 帕瓦特"," 哉阿斯"," 迪迦 ","戴拿","盖亚","阿古茹","纳伊斯","高斯","杰斯提斯","雷杰多","奈克斯特","奈克赛斯","诺亚","奈欧斯","赛文21","麦克斯","杰诺","梦比优斯","希卡利","赛罗","赛迦","银和","维克特利","捷德","欧布","罗索","布鲁","格丽乔");

2.把list作为参数重新构建一个ArrayList集合

  public static void main(String[] args) {List<String> list = Arrays.asList("佐菲","初代","赛文","杰克","艾斯","泰罗","奥特之父","奥特之母","雷欧","阿斯特拉","奥特之王","乔尼亚斯"," 爱迪"," 史考特"," 查克"," 贝斯"," 葛雷"," 帕瓦特"," 哉阿斯"," 迪迦 ","戴拿","盖亚","阿古茹","纳伊斯","高斯","杰斯提斯","雷杰多","奈克斯特","奈克赛斯","诺亚","奈欧斯","赛文21","麦克斯","杰诺","梦比优斯","希卡利","赛罗","赛迦","银和","维克特利","捷德","欧布","罗索","布鲁","格丽乔");ArrayList<String> name=new ArrayList<>(list);

3.使用Scanner、Random、ArrayList完成一个不重复的点名程序

 public static void main(String[] args) {List<String> list = Arrays.asList("佐菲","初代","赛文","杰克","艾斯","泰罗","奥特之父","奥特之母","雷欧","阿斯特拉","奥特之王","乔尼亚斯"," 爱迪"," 史考特"," 查克"," 贝斯"," 葛雷"," 帕瓦特"," 哉阿斯"," 迪迦 ","戴拿","盖亚","阿古茹","纳伊斯","高斯","杰斯提斯","雷杰多","奈克斯特","奈克赛斯","诺亚","奈欧斯","赛文21","麦克斯","杰诺","梦比优斯","希卡利","赛罗","赛迦","银和","维克特利","捷德","欧布","罗索","布鲁","格丽乔");ArrayList<String> name=new ArrayList<>(list);Random ra=new Random();Scanner sc=new Scanner(System.in);

4.循环判断如果集合中没有元素了，则结束循环

public static void main(String[] args) {List<String> list = Arrays.asList("佐菲","初代","赛文","杰克","艾斯","泰罗","奥特之父","奥特之母","雷欧","阿斯特拉","奥特之王","乔尼亚斯"," 爱迪"," 史考特"," 查克"," 贝斯"," 葛雷"," 帕瓦特"," 哉阿斯"," 迪迦 ","戴拿","盖亚","阿古茹","纳伊斯","高斯","杰斯提斯","雷杰多","奈克斯特","奈克赛斯","诺亚","奈欧斯","赛文21","麦克斯","杰诺","梦比优斯","希卡利","赛罗","赛迦","银和","维克特利","捷德","欧布","罗索","布鲁","格丽乔");ArrayList<String> name=new ArrayList<>(list);Random ra=new Random();Scanner sc=new Scanner(System.in);while (true){//如果集合中没有元素了，则结束循环if(name.size()==0){System.out.println("已完成所有名字抽查，抽查结束请重新开始");break;}System.out.println("确认点名请输入Y/y");String input=sc.next();if(input.equals("y") || input.equals("y")){//随机一个集合下标int index=ra.nextInt(name.size());System.out.println("本次抽到"+name.get(index));//该名字已被抽到，把他从集合中移除name.remove(index);}else {System.out.println("本次抽查结束");break;}}}

如果不想继续抽取则随便输入另外一个字母结束抽查

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