Mastering Java if…else: Control Flow Explained

Java if…else Statements

Master Java control flow with clear examples of if, if‑else, else‑if, and nested statements.

In programming, the if…else construct determines which block of code runs based on a Boolean test. It’s the foundation for making decisions in Java.

For instance, assigning letter grades from a numeric score:

• If the score is above 90, the grade is A
• If the score is above 75, the grade is B
• If the score is above 65, the grade is C

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1. Java if (if‑then) Statement

The syntax of an if‑then statement is:

if (condition) {
    // statements
}

Here, condition is a Boolean expression, such as age >= 18.

• If condition evaluates to true, the statements run.
• If condition evaluates to false, the statements are skipped.

How the if Statement Works

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Example 1: Java if Statement

class IfStatement {
    public static void main(String[] args) {
        int number = 10;
        // check if number is negative
        if (number < 0) {
            System.out.println("The number is negative.");
        }
        System.out.println("Statement outside if block");
    }
}

Output

Statement outside if block

Because number < 0 is false, the code inside the if block is skipped.

Tip: Learn more about test conditions in Java Relational Operators and Java Logical Operators.

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Java can also use String values in the test condition.

Example 2: Java if with String

class Main {
    public static void main(String[] args) {
        String language = "Java";
        if (language == "Java") {
            System.out.println("Best Programming Language");
        }
    }
}

Output

Best Programming Language

This example demonstrates comparing two strings inside an if block.

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2. Java if…else (if‑then‑else) Statement

The if block executes when the test expression is true; otherwise, the optional else block runs.

The syntax is:

if (condition) {
    // code for true
} else {
    // code for false
}

This structure allows a single decision to branch into two distinct paths.

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How the if…else Statement Works

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Example 3: Java if…else Statement

class Main {
    public static void main(String[] args) {
        int number = 10;
        if (number > 0) {
            System.out.println("The number is positive.");
        } else {
            System.out.println("The number is not positive.");
        }
        System.out.println("Statement outside if…else block");
    }
}

Output

The number is positive.
Statement outside if…else block

Changing number to -5 flips the outcome, demonstrating the else branch.

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3. Java if…else…if Ladder

The if…else…if chain evaluates each condition in order, executing the first block whose condition is true. If none match, the final else runs.

if (condition1) {
    // code
} else if (condition2) {
    // code
} else if (condition3) {
    // code
} else {
    // default code
}

This pattern is ideal for multi‑way branching.

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How the if…else…if Ladder Works

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Example 4: Java if…else…if Statement

class Main {
    public static void main(String[] args) {
        int number = 0;
        if (number > 0) {
            System.out.println("The number is positive.");
        } else if (number < 0) {
            System.out.println("The number is negative.");
        } else {
            System.out.println("The number is 0.");
        }
    }
}

Output

The number is 0.

With number set to zero, both preceding conditions fail, so the else block executes.

Note: Java’s ternary operator offers a concise form of if…else…if; see Java Ternary Operator for details.

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4. Nested if…else Statements

Nested if…else blocks allow hierarchical decision making, useful for comparing multiple values.

Example 5: Finding the Largest of Three Numbers

class Main {
    public static void main(String[] args) {
        Double n1 = -1.0, n2 = 4.5, n3 = -5.3, largest;
        if (n1 >= n2) {
            if (n1 >= n3) {
                largest = n1;
            } else {
                largest = n3;
            }
        } else {
            if (n2 >= n3) {
                largest = n2;
            } else {
                largest = n3;
            }
        }
        System.out.println("Largest Number: " + largest);
    }
}

Output

Largest Number: 4.5

In practice, the values often come from user input, files, or network sources rather than hard‑coded constants.