Question

How to input a number from console into an int with Java

Answer 1

package javaapplication1;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class JavaApplication1 {

    public static void main(String[] args) {

        try {

            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

            System.out.print("Enter a number: ");
            String s = br.readLine();
            int n = Integer.parseInt(s);
            System.out.println(n);

        } catch (IOException | NumberFormatException e) {
            System.out.println(e.toString());
        }
    }
}

/*
              
run:
 
Enter a number: 123
123
     
 */

 

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Answer 2

package javaapplication1;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class JavaApplication1 {

    public static void main(String[] args) throws IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        while (true) {
            System.out.print("Enter a number: ");
            String s = br.readLine();
            int n;
            try {
                n = Integer.parseInt(s);
                System.out.println(n);
                break;
            } catch (NumberFormatException exception) {
                System.out.println("Not a number: " + exception);
            }
        }
    }
}

/*
              
run:
 
Enter a number: a
Not a number: java.lang.NumberFormatException: For input string: "a"
Enter a number: w
Not a number: java.lang.NumberFormatException: For input string: "w"
Enter a number: 13
13
     
 */

 

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