使用Java Scanner时输入无显示，Eclipse环境下问题求助

Hey there! Let's work through why your Eclipse console isn't behaving as expected with that simple Scanner code. Let's break down the possible issues and fixes step by step:

First, Let's Understand Your Code #

Your current code creates a Scanner object and prints "yo", but it doesn't actually read any input from the console. That means the program runs, prints "yo", and immediately exits—so if you're trying to type input, the program has already finished by the time you do!

But if you're not even seeing the "yo" message, we'll cover that scenario too.

Scenario 1: Console Doesn't Show Any Output (Not Even "yo") #

• Check if the Console view is open: Go to Window → Show View → Console to make sure the console panel is visible in Eclipse. Sometimes it gets hidden or closed by accident.
• Verify you're running the program correctly: Right-click your test.java file, select Run As → Java Application. Don't run it as a different type of configuration (like a JUnit test) unless that's intentional.
• Clean and rebuild your project: Go to Project → Clean, select your project, and click OK. This clears old compiled files that might be causing issues. Then re-run the program.
• Check your JRE configuration: Make sure your project is using a valid, installed JRE. Go to Project Properties → Java Build Path → Libraries, check that JRE System Library is listed and doesn't have a red error icon. If it does, click Edit to select a working JRE from your system.

Scenario 2: Console Shows "yo" But Doesn't Respond to Input #

This is the most likely case with your current code. Since you haven't added any code to read input, the program exits right after printing "yo". To fix this, add a line to read input from the Scanner, like this:

import java.io.*;
import java.util.*;
public class test {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.println("yo");
        
        // Add this line to wait for user input
        String userInput = input.nextLine();
        
        // Optional: Print the input to confirm it's working
        System.out.println("You entered: " + userInput);
        
        // Always close the Scanner when done
        input.close();
    }
}

Now when you run the program:

1. The console will show "yo"
2. The program will pause and wait for you to type something and press Enter
3. It will print back what you entered, then exit

One More Quick Check #

If you still can't type into the console, make sure the console panel has focus—click inside the console area to activate it before typing. Sometimes Eclipse doesn't automatically give focus to the input field.

内容的提问来源于stack exchange，提问作者htmlnoob