当前位置：首页 > news >正文

java遍历

news 来源：原创 2025/6/9 8:16:13

增强for循环（也称for each循环）是JDK1.5以后出来的一个高级for循环，专门用来遍历数组和集合。
它的内部原理其实是个Iterator迭代器，所以在遍历的过程中，不能对集合中的元素进行增删操作
增强for循环基本语法
for(元素类型变量名：集合名或数组名){

}

使用三种不同循环遍历List<Student>
1.传统for循环
2.迭代器Iterator
3.增强for循环底层基于迭代器Iterator

package com.xd;

import java.util.ArrayList;

public class Test {
    public static void main(String[] args) {
        // 增强for循环 for each 遍历 数组和集合
        int[] arr = new int[]{60,70,50,90};
        for (int i = 0; i < arr.length; i++) {
            System.out.println(arr[i]);
        }

        for (int j : arr) {
            System.out.println(j);
        }

        String[] strs = {"01","02","03"};
        for (String str : strs) {
            System.out.println(str);
        }

        ArrayList<String> arrayList = new ArrayList<>();
        arrayList.add("01");
        arrayList.add("02");
        arrayList.add("03");
        for (String str:arrayList){
            System.out.println(str);
        }


    }
}

package com.xd;

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

public class Test02 {
    public static void main(String[] args) {
        List<Student> students = new ArrayList<>();
        students.add(new Student("a",1));
        students.add(new Student("b",2));
        students.add(new Student("c",3));
        // 方式一遍历 集合
        for (int i=0;i<students.size();i++){
            Student student = students.get(i);
            System.out.println(student.getName() + "," + student.getAge());

        }
        // 方式二遍历 迭代器遍历集合
        Iterator<Student> iterator = students.iterator();
        while (iterator.hasNext()) {
            Student student = iterator.next();
            System.out.println(student.getName() + "," + student.getAge());
        }
        // 方式三 增强for循环 foreach
        for (Student stu:students) {


            System.out.println(stu.getName() + "," + stu.getAge());

        }



    }
}