Literals

A school program needs reliable data and clear rules. A literal writes a value directly in source code. Numbers, quoted text and true or false have different types, so a student’s name and mark need different representations.

In Java, literals are the most direct way to represent fixed values in your code. They anchor your program’s meaning with concrete data—like numbers, text, or true/false flags—helping the compiler and readers alike understand exactly what you intend.

Integers can be expressed in four bases:

• Decimal (base 10): the default, e.g. 42
• Binary (base 2): prefix with 0b or 0B, e.g. 0b101010
• Octal (base 8): prefix with 0, e.g. 052
• Hexadecimal (base 16): prefix with 0x or 0X, e.g. 0x2A

public class IntegerLiteralsExample {
    public static void main(String[] args) {
        int dec = 42;
        int bin = 0b101010;
        int oct = 052;
        int hex = 0x2A;
        System.out.println(dec);
        System.out.println(bin);
        System.out.println(oct);
        System.out.println(hex);
    }
}

42
42
42
42

All four declarations yield the same numeric value, showcasing Java’s flexible syntax.

By default, decimal fractions are double. To specify a float, append f or F:

public class FloatLiteralsExample {
    public static void main(String[] args) {
        double d1 = 3.14159;
        float  f1 = 3.14159F;
        System.out.println(d1);
        System.out.println(f1);
    }
}

3.14159
3.14159

Note that without F, the compiler treats the literal as double and will flag an error if assigned to float.

Boolean literals are straightforward: true and false. They power conditional logic:

public class BooleanLiteralsExample {
    public static void main(String[] args) {
        boolean isJavaFun = true;
        boolean isFishTasty = false;
        System.out.println(isJavaFun);
        System.out.println(isFishTasty);
    }
}

true
false

Character literals represent single UTF-16 code units, enclosed in single quotes:

• 'A' for letters
• '7' for digits
• Escape sequences like ' ', '\u03A9' (Ω)

public class CharLiteralsExample {
    public static void main(String[] args) {
        char letter = 'J';
        char digit  = '9';
        char newline = '\n';
        char omega  = '\u03A9';
        System.out.println(letter);
        System.out.println(digit);
        System.out.println(newline);
        System.out.println(omega);
    }
}

J
9

Ω

Strings are sequences of characters wrapped in double quotes. Java 15+ also supports text blocks using triple quotes:

public class StringLiteralsExample {
    public static void main(String[] args) {
        String greeting = "Hello, Java!";
        String poem = """
                      Roses are red,
                      Violets are blue,
                      Java is great,
                      And so are you!
                      """;
        System.out.println(greeting);
        System.out.println(poem);
    }
}

Hello, Java!
Roses are red,
Violets are blue,
Java is great,
And so are you!

The special literal null indicates the absence of an object reference:

public class NullLiteralExample {
    public static void main(String[] args) {
        String text = null;
        if (text == null) {
            System.out.println("No text assigned yet.");
        }
    }
}

No text assigned yet.

Use null carefully to avoid NullPointerException.

A quoted number is text. A character literal uses single quotes; a String uses double quotes.

Before running this Java program, write down each line you expect to see. Identify the value, branch, object or exception responsible for each line. Then explain whether the following assumption is valid: A quoted number is text.

Java 17 · Main.java · complete practice program

public class Main  {
  public static void main(String[] args)  {
    String name = "Diya";
    int marks = 72;
    System.out.println(name + ": " + marks);
  }
}

Now change one thing: Replace the name Diya with Saira. Predict the new behavior before checking the worked variation.

Java 17 · Main.java · source repeated for this answer

public class Main  {
  public static void main(String[] args)  {
    String name = "Diya";
    int marks = 72;
    System.out.println(name + ": " + marks);
  }
}

Expected output

Diya: 72

A literal writes a value directly in source code. Numbers, quoted text and true or false have different types, so a student’s name and mark need different representations.

A quoted number is text. A character literal uses single quotes; a String uses double quotes.

Run with javac Main.java, then java Main. The declaration of Main names the class; main starts the example, and println writes a complete output line.

Worked variation: Replace the name Diya with Saira. The numeric mark remains 72 and the report label changes.

A literal writes a value directly in source code. Numbers, quoted text and true or false have different types, so a student’s name and mark need different representations. A quoted number is text. A character literal uses single quotes; a String uses double quotes.

Related explanations: Java Variables, Java If Statement - Syntax and Examples, Java Class - Blueprint of Objects, Exceptions in Java Introduction.

Supporting documentation: Official Java learning guide and Java 17 language specification.