How can I read input from the console using the Scanner class in Java?

Question

How could I read input from the console using the Scanner class? Something like this:

System.out.println(\"Enter your username: \");
Scanner = i         


        

Answer 1

There is a simple way to read from the console.

Please find the below code:

import java.util.Scanner;

    public class ScannerDemo {

        public static void main(String[] args) {
            Scanner sc = new Scanner(System.in);

            // Reading of Integer
            int number = sc.nextInt();

            // Reading of String
            String str = sc.next();
        }
    }

For a detailed understanding, please refer to the below documents.

Doc

Now let's talk about the detailed understanding of the Scanner class working:

public Scanner(InputStream source) {
    this(new InputStreamReader(source), WHITESPACE_PATTERN);
}

This is the constructor for creating the Scanner instance.

Here we are passing the InputStream reference which is nothing but a System.In. Here it opens the InputStream Pipe for console input.

public InputStreamReader(InputStream in) {
    super(in);
    try {
        sd = StreamDecoder.forInputStreamReader(in, this, (String)null); // ## Check lock object
    }
    catch (UnsupportedEncodingException e) {
        // The default encoding should always be available
        throw new Error(e);
    }
}

By passing the System.in this code will opens the socket for reading from console.