How to display output in Java Programming

In Java, output is typically displayed on the screen using the System.out.println() method. This method is an essential tool for showing text, variables, and other data types to the user.

Displaying Text with System.out.println()

The simplest way to output text in Java is by using the System.out.println() method. Let’s look at an example:

public class Main {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

Explanation:

• System: This is a built-in class in Java that provides access to system resources.
• out: This is an output stream that is connected to the console.
• println(): This method prints the text passed to it and moves the cursor to the next line.

When you run the code above, the output will be:

Hello, World!

Using System.out.print() for Output

Java also provides the System.out.print() method, which is similar to System.out.println() but with one key difference: it does not move the cursor to a new line after printing. This means that subsequent output will appear on the same line.

public class Main {
    public static void main(String[] args) {
        System.out.print("Hello, ");
        System.out.print("World!");
    }
}

Output:

Hello, World!

As you can see, both pieces of text appear on the same line.

Formatting Output with System.out.printf()

For more complex output formatting, Java offers the System.out.printf() method. This method allows you to format strings in a more controlled way. Here’s an example:

public class Main {
    public static void main(String[] args) {
        int age = 25;
        String name = "John";
        System.out.printf("My name is %s and I am %d years old.", name, age);
    }
}

Explanation:

• %s is a placeholder for a string.
• %d is a placeholder for an integer.

Output:

My name is John and I am 25 years old.

This method is useful when you need to format your output, such as displaying data in a specific layout.

Concatenating Strings

You can also concatenate (join together) strings and variables in the System.out.println() method:

public class Main {
    public static void main(String[] args) {
        String firstName = "Jane";
        String lastName = "Doe";
        System.out.println("Full Name: " + firstName + " " + lastName);
    }
}

Output:

Full Name: Jane Doe

The + operator is used to concatenate the strings and variables.

Escape Sequences

Sometimes you might need to include special characters in your output, such as quotation marks or new lines. Java provides escape sequences for this purpose:

• \n: Inserts a new line.
• \": Inserts a double quote.
• \\: Inserts a backslash.

Example:

public class Main {
    public static void main(String[] args) {
        System.out.println("This is a \"quote\".");
        System.out.println("First Line\nSecond Line");
        System.out.println("A backslash: \\");
    }
}

Output:

This is a "quote".
First Line
Second Line
A backslash: \

Summary

In this chapter, you’ve learned how to display output in Java using System.out.println(), System.out.print(), and System.out.printf(). You’ve also seen how to concatenate strings, use escape sequences, and format your output. These methods are fundamental for interacting with users and displaying the results of your program’s logic. As you continue learning Java, you’ll find these output techniques essential for debugging and presenting information effectively.