How do you read input from Java System.in in a Java program?

General Discussions
, ,
2

Hey, from my experience, the simplest way to read input from java system.in when running your program with java myProg < file is by using a Scanner. It’s pretty straightforward. Here’s a quick example:

import java.util.Scanner;

public class MyProg {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        StringBuilder content = new StringBuilder();
        
        while (scanner.hasNextLine()) {
            content.append(scanner.nextLine()).append("\n");
        }
        
        scanner.close();
        System.out.println("File Content:\n" + content);
    }
}

This code will read the entire file line by line and store it in a StringBuilder. You can process it as you want later. Works well for most cases, especially for simpler tasks.