JAVA Tutorial

If-Else in Java

The if-else statement in Java allows you to execute certain code based on a condition. It helps you control the flow of your program by making decisions. The basic structure is simple:

if (condition) {
    // Code to execute if the condition is true
} else {
    // Code to execute if the condition is false
}
  

💡 Basic Example of If-Else

Let's start with a simple example to check if a number is positive or negative:

public class IfElseExample {
    public static void main(String[] args) {
        int number = -5;

        if (number > 0) {
            System.out.println("The number is positive.");
        } else {
            System.out.println("The number is negative.");
        }
    }
}
  

🔴 Understanding the Condition

In the code above, we used the condition number > 0. If this condition is true (i.e., if the number is greater than 0), the program prints "The number is positive." Otherwise, it prints "The number is negative."

💡 Using Else-If for Multiple Conditions

You can extend the if-else structure using else-if to check for multiple conditions. Here's an example to check if a number is positive, negative, or zero:

public class ElseIfExample {
    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 zero.");
        }
    }
}
  

⚙️ Combining Multiple Conditions

You can also combine multiple conditions using logical operators like && (AND), || (OR), and ! (NOT). For example:

public class CombinedConditions {
    public static void main(String[] args) {
        int age = 20;
        boolean hasLicense = true;

        if (age >= 18 && hasLicense) {
            System.out.println("You can drive.");
        } else {
            System.out.println("You cannot drive.");
        }
    }
}
  

📖 Nested If-Else Statements

Java allows you to use if-else statements inside other if-else statements, which are called nested if-else statements. Here's an example:

public class NestedIfElseExample {
    public static void main(String[] args) {
        int num = 15;

        if (num > 0) {
            if (num % 2 == 0) {
                System.out.println("The number is positive and even.");
            } else {
                System.out.println("The number is positive and odd.");
            }
        } else {
            System.out.println("The number is non-positive.");
        }
    }
}
  

🔴 Ternary Operator - Shortened If-Else

Java also provides the ternary operator ? as a shorthand for simple if-else statements:

public class TernaryExample {
    public static void main(String[] args) {
        int number = 10;
        String result = (number > 0) ? "Positive" : "Non-positive";
        System.out.println(result);
    }
}
  

💡 Key Takeaways

• Use if to execute code when a condition is true.
• Use else for code to run when the condition is false.
• else-if allows you to check multiple conditions.
• Logical operators like &&, ||, and ! help combine conditions.
• The ternary operator provides a compact alternative for simple if-else statements.