Java provides several classes and methods to perform input and output (I/O) operations. In this section, we will cover basic I/O operations using the Scanner class for input and the System.out class for output.

Output in Java

Java provides the System.out class to perform output operations. The System.out.println method is commonly used to print text to the console.

Example 

  public class OutputExample {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
        System.out.println("Java programming is fun.");
    }
}

Explanation

  • System.out.println("Hello, World!"); prints “Hello, World!” followed by a new line.
  • System.out.println("Java programming is fun."); prints “Java programming is fun.” followed by a new line.

Input in Java

To read input from the user, we can use the Scannerclass from the java.util package. The Scanner class provides various methods to read different types of input.

Example 

  import java.util.Scanner;

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

        System.out.print("Enter your name: ");
        String name = scanner.nextLine();

        System.out.println("Hello, " + name + "!");
    }
}

Explanation

  • import java.util.Scanner; imports the Scanner class.
  • Scanner scanner = new Scanner(System.in); creates a Scanner object to read input from the standard input stream (keyboard).
  • String name = scanner.nextLine(); reads a line of text entered by the user.
  • System.out.println("Hello, " + name + "!"); prints a greeting message that includes the user’s name.

Reading Different Types of Input

The Scanner class provides methods to read various types of input, such as integers, doubles, and booleans.

Example 

  import java.util.Scanner;

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

        System.out.print("Enter an integer: ");
        int intValue = scanner.nextInt();

        System.out.print("Enter a double: ");
        double doubleValue = scanner.nextDouble();

        System.out.print("Enter a boolean: ");
        boolean booleanValue = scanner.nextBoolean();

        System.out.println("Integer: " + intValue);
        System.out.println("Double: " + doubleValue);
        System.out.println("Boolean: " + booleanValue);
    }
}

Explanation

  • int intValue = scanner.nextInt(); reads an integer input.
  • double doubleValue = scanner.nextDouble(); reads a double input.
  • boolean booleanValue = scanner.nextBoolean(); reads a boolean input.

Example Program

Here is a complete example program that combines input and output operations:

  import java.util.Scanner;

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

        System.out.print("Enter your name: ");
        String name = scanner.nextLine();

        System.out.print("Enter your age: ");
        int age = scanner.nextInt();

        System.out.print("Enter your height in meters: ");
        double height = scanner.nextDouble();

        System.out.println("\nUser Information:");
        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
        System.out.println("Height: " + height + " meters");
    }
}

Explanation

  • The program reads the user’s name, age, and height.
  • The program then prints the collected information.