Java中List集合的三种遍历方式(全网最详)

Posted 2021-03-04 小猫钓鱼吃鱼

介绍3种方式遍历list集合

1 创建一个model

public class News{
    private int id;
    private String title;
    private String author;
    
    public News(int id, String title, String author) {
        super();
        this.id = id;
        this.title = title;
        this.author = author;
    }
    
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getAuthor() {
        return author;
    }

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

}

　方式一  第一种、最基础的遍历方式：for循环，指定下标长度，使用List集合的size()方法，进行for循环遍历

import java.util.ArrayList;

public class Demo01 {

　　public static void main(String[] args) {
　　　ArrayList<News> list = new ArrayList<News>();
　　　　
　　　list.add(new News(1,"list1","a"));
　　　list.add(new News(2,"list2","b"));
　　　list.add(new News(3,"list3","c"));
　　　list.add(new News(4,"list4","d"));
　　　for (int i = 0; i < list.size(); i++) {
            News s = (News)list.get(i);
            System.out.println(s.getId()+"  "+s.getTitle()+"  "+s.getAuthor());
　　　　}
　　}
}

　　第二种、较为简洁的遍历方式：使用foreach遍历List，但不能对某一个元素进行操作（这种方法在遍历数组和Map集合的时候同样适用）

import java.util.ArrayList;

public class Demo02 {

　　public static void main(String[] args) {

　　　　ArrayList<News> list = new ArrayList<News>();

　　　　　list.add(new News(1,"list1","a"));
		　　　　　list.add(new News(2,"list2","b"));
		　　　　　list.add(new News(3,"list3","c"));
		　　　　　list.add(new News(4,"list4","d"));
　　　　for (News s : list) {
            System.out.println(s.getId()+"  "+s.getTitle()+"  "+s.getAuthor());
　　　}
　　}
}

　　第三种、适用迭代器Iterator遍历：直接根据List集合的自动遍历

import java.util.ArrayList;

public class Demo03 {

　　public static void main(String[] args) {

　　　ArrayList<News> list = new ArrayList<News>();
　　　　
　　　list.add(new News(1,"list1","a"));
　　　list.add(new News(2,"list2","b"));
　　　list.add(new News(3,"list3","c"));
　　　list.add(new News(4,"list4","d"));
　　　
     Iterator<News> iter = list.iterator();
     while (iter.hasNext()) {
            News s = (News) iter.next();
            System.out.println(s.getId()+"  "+s.getTitle()+"  "+s.getAuthor());
　　　 }
　　}
}