How To Get User Input in Java

The Problem

I don’t know how to get user input from the console in Java.

The Solution

The most common way to get user input in Java is to use the Scanner class from the java.util package.

For example, the following code uses Scanner with methods such as nextLine() to retrieve different data inputs:

import java.util.Scanner;

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

        System.out.print("Enter your name: ");
        String name = scanner.nextLine(); // Read a full line of text
        System.out.println("Hello, " + name + "!");

        System.out.print("Enter your age: ");
        int age = scanner.nextInt(); // Read an integer input
        System.out.println("You are " + age + " years old.");

        System.out.print("Enter a decimal number: ");
        double number = scanner.nextDouble(); // Read a double input
        System.out.println("You entered: " + number);

        scanner.close(); // Close the scanner to free resources
    }
}

This demonstrates the following commonly used methods for reading user input:

• The nextLine() method reads a full line of text.
• The nextInt() method reads an integer.
• The nextDouble() method reads a double.

While each method gets a different data type, the Java Scanner class does not offer a native means of reading character input.

If you need to read a single character, you can use nextLine() to fetch a line of text, then extract the first character of that line:

System.out.print("Enter a character: ");
char ch = scanner.nextLine().charAt(0); // Read first character from input
System.out.println("You entered: " + ch);

You can use try-catch blocks to prevent the program from crashing when invalid input is entered:

import java.util.InputMismatchException;
import java.util.Scanner;

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

        try {
            System.out.print("Enter an integer: ");
            int number = scanner.nextInt();
            System.out.println("You entered: " + number);
        } catch (InputMismatchException e) {
            System.out.println("Invalid input! Please enter a valid integer.");
        }

        scanner.close();
    }
}

Further Reading

• The Java Scanner documentation
• The Java InputMismatchException documentation