If and If-Else Statements in Java

The if statement is the most frequently used conditional statement in Java — it is hard to write a program without it. It directs program execution down one of two (or more) branches depending on whether a condition is true or false.

1. If Statement in Java

The general syntax of the if statement:

if (booleanExpression) {
     System.out.println("In the if block");
}

Here booleanExpression must evaluate to a value of type boolean or Boolean. If it evaluates to true, the code inside the curly braces executes. If it evaluates to false, the block is skipped and execution continues after the closing brace.

The following example demonstrates the if statement:

public class IfExample {
    public static void main(String[] args) {
        int a = 1;
        if (a < 10) {
            System.out.println("In the if block");
        }
    }
}

2. If-Else Statement

The if statement can include an else block. When booleanExpression evaluates to false, the code after else executes instead:

if (booleanExpression) {
    System.out.println("Inside if block");
} else {
    System.out.println("Inside else block");
}

The following example shows the if-else statement in action:

public class IfElseExample {
    public static void main(String[] args) {
        int a = 1;
        if (a == 10) {
            System.out.println("In the if block");
        } else {
            System.out.println("In the else block");
        }
    }
}

The block that follows if or else may contain several statements.

3. If-Else-If Ladder

The if-else-if ladder is a special case of the if-else structure. An if statement may have zero or more else if branches, which must come before the optional final else. Conditions are tested from top to bottom; as soon as one of them is true, its block runs and none of the remaining else if or else branches are evaluated.

Consider an example:

public class IfElseExample1 {
    public static void main(String[] args) {
        int month = 4; // April
        String season;
        if (month == 12 || month == 1 || month == 2) {
            season = "Winter";
        } else if (month == 3 || month == 4 || month == 5) {
            season = "Spring";
        } else if (month == 6 || month == 7 || month == 8) {
            season = "Summer";
        } else if (month == 9 || month == 10 || month == 11) {
            season = "Autumn";
        } else {
            season = "Not a Month";
        }
        System.out.println("April is in the " + season + ".");
    }
}

Output:

April is in the Spring.

Which Form to Choose

Where Beginners Slip Up

• A semicolon right after the condition: if (a > 5); compiles, but the semicolon is an empty statement — the block below it runs unconditionally.
• Skipping braces on single-line branches, then adding a second line that silently ends up outside the branch. Always use {}.
• Comparing objects with ==: for String and other objects use equals() inside conditions; == compares references.

By mastering if, if-else, and the if-else-if ladder, you gain full control over the flow of your Java programs.