Java Conditional Statements

Conditional statements allow you to run a specific block of code out of multiple options based on certain conditions. They help manage the flow of execution within a Java program. Below are the main types of conditional statements in Java:

1. if

The syntax of an if statement is:

if (condition) {
    // Code to be executed if condition evaluates to true
}

Here, condition is a boolean expression. If the condition evaluates to true, the code inside the if block will be executed. If the condition is false, the code within the if block will be skipped.

Example

public class Main {

    public static void main(String[] args) {
        int age = 25;

        if (age > 20) {
            System.out.println("You are older than 20.");
        }
    }
}

Output

You are older than 20.

2. if-else

The syntax of an if-else statement is:

if (condition) {
    // Code to be executed if condition evaluates to true
} else {
    // Code to be executed if condition evaluates to false
}

In this case, condition is again a boolean expression. If the condition is true, the code in the if block executes; if it’s false, the code in the else block runs.

Example

public class Main {

    public static void main(String[] args) {
        int age = 18;

        if (age > 20) {
            System.out.println("You are older than 20.");
        } else {
            System.out.println("You are younger than 20.");
        }
    }
}

Output

You are younger than 20.

3. if-else if-else

The if-else if-else statement allows you to check multiple conditions, each of which is a boolean expression. The code corresponding to the first true condition will execute, and if no conditions are met, the final else block will run. The syntax is:

if (condition1) {
    // Code to be executed if condition1 evaluates to true
} else if (condition2) {
    // Code to be executed if condition2 evaluates to true
} else {
    // Code to be executed if none of the conditions are true
}

Example

public class Main {

    public static void main(String[] args) {
        int age = 18;

        if (age > 20) {
            System.out.println("You are older than 20.");
        } else if (age > 15) {
            System.out.println("You are older than 15.");
        } else {
            System.out.println("You're younger.");
        }
    }
}

Output

You are older than 15.

4. switch

The switch statement offers a clearer and more compact alternative to using if-else if-else statements when handling multiple possible values for a single variable. Its syntax is:

switch (expression) {
    case value1:
        // Code to be executed if expression matches value1
        break;
    case value2:
        // Code to be executed if expression matches value2
        break;
    default:
        // Code to be executed if no case matches
}

Here, the expression is evaluated once and compared against the values of each case. If the expression matches value1, the code under case value1: is executed. Similarly, if the expression matches value2, the code under case value2: is run. If there is no match, the code under default: will be executed.

Example

public class Main {

    public static void main(String[] args) {
        int age = 25;

        switch (age) {
            case 30:
                System.out.println("You are 30 years old.");
                break;
            case 25:
                System.out.println("You are 25 years old.");
                break;
            default:
                System.out.println("You are neither 30 nor 20 years old.");
        }
    }
}

Output

You are 25 years old.

5. Ternary Operator

The ternary operator provides a compact way to write an if-else statement. The syntax is:

variable = (condition) ? value1 : value2;

Here, variable is assigned value1 if the condition is true, and value2 otherwise.

Example

public class Main {

    public static void main(String[] args) {
        int age = 25;
        boolean isOver20 = (age > 20) ? true : false;

        System.out.println(isOver20);
    }
}

Output

true