The if-else if-else statement in Java allows you to evaluate multiple conditions in sequence. It is useful when you need to check several different conditions and execute different blocks of code based on which condition evaluates to true.

Syntax of if-else if-else Statement

if (condition1) {
    // Block of code to be executed if condition1 is true
} else if (condition2) {
    // Block of code to be executed if condition2 is true
} else if (condition3) {
    // Block of code to be executed if condition3 is true
} else {
    // Block of code to be executed if none of the above conditions are true
}

• condition1, condition2, condition3: These are boolean expressions that are evaluated in order.
• Blocks of code: The code inside the braces {} will execute for the first true condition found. If none of the conditions are true, the code in the else block executes.

Example of if-else if-else Statement

Here’s a simple example demonstrating the use of an if-else if-else statement to categorize a number:

public class IfElseIfElseExample {
    public static void main(String[] args) {
        int number = 0;

        // Using if-else if-else statement to categorize the number
        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 zero.");
        }
    }
}

Explanation

1. Declaration: The variable number is declared and initialized with the value 0.
2. Condition Check:
   • The first condition (number > 0) checks if the number is positive. It evaluates to false.
   • The second condition (number < 0) checks if the number is negative. It also evaluates to false.
   • Since neither of the first two conditions is true, the code in the else block executes.
3. Execution: The program outputs:

   The number is zero.
   

Example with Multiple Conditions

Here’s another example that uses an if-else if-else statement to determine the grade based on a score:

public class GradeCalculator {
    public static void main(String[] args) {
        int score = 85;

        // Using if-else if-else statement to determine the grade
        if (score >= 90) {
            System.out.println("Grade: A");
        } else if (score >= 80) {
            System.out.println("Grade: B");
        } else if (score >= 70) {
            System.out.println("Grade: C");
        } else if (score >= 60) {
            System.out.println("Grade: D");
        } else {
            System.out.println("Grade: F");
        }
    }
}

Explanation

In this example:

• The variable score is initialized with the value 85.
• The program checks the score against several conditions:
  • If the score is 90 or above, it assigns an "A".
  • If the score is 80 or above, it assigns a "B".
  • If the score is 70 or above, it assigns a "C".
  • If the score is 60 or above, it assigns a "D".
  • If the score is below 60, it assigns an "F".
• Since 85 is greater than 80 but less than 90, the output will be:

  Grade: B
  

Summary

The if-else if-else statement is a powerful control structure in Java that allows you to evaluate multiple conditions sequentially. It helps in making decisions based on different scenarios, making your code more flexible and dynamic. Understanding how to use this control structure effectively is essential for creating robust Java applications.