java 标准输出流、标准错误输出流、标准输入流及扫描仪

package com.mydemo.controller;

import java.util.Scanner;

public class HelloWorld {
    public static void main(String[] args) {
        System.err.println("HelloWorld");
        System.out.println("HelloWorld");
        
        System.out.println(System.in);
        System.out.println(System.out);
        System.out.println(System.err);
        
        Scanner scanner = new Scanner(System.in);
        String nextLine = scanner.nextLine();
    }
}

HelloWorld
HelloWorld
java.io.BufferedInputStream@2a139a55
java.io.PrintStream@15db9742
java.io.PrintStream@6d06d69c

 1 package com.mydemo.controller;
 2 
 3 import java.util.Scanner;
 4 
 5 public class HelloWorld {
 6     public static void main(String[] args) {
 7         @SuppressWarnings("resource")
 8         Scanner scanner = new Scanner(System.in);//这一行打断点
 9         String nextLine = scanner.nextLine();    //这一行打断点
10         System.out.println(nextLine);　　　　　　  //这一行打断点
11     }
12 }