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One of the first and most important things you’ll learn in Java programming is how to make decisions in your code. That’s where if-else statements come in. They let your program decide what to do next based on a condition—just like how we make decisions in everyday life.
For example:
“If it’s raining, take an umbrella. Otherwise, wear sunglasses.”
In Java, we can write this kind of logic using if, else if, and else. In this article, you’ll learn what if-else statements are, how they work, and how to use them to add decision-making power to your Java programs.
Let’s get started!

What Is an If-Else Statement?

An if-else statement is a control structure that lets you run different blocks of code based on whether a condition is true or false.
Here’s the basic idea: 
if (condition) {
    // do this if the condition is true
} else {
    // do this if the condition is false
}

The Basic If Statement

The if statement checks a condition. If it’s true, the code inside the block runs.
Example: 
int age = 20;

if (age >= 18) {
    System.out.println("You are an adult.");
}
Since age is 20, the condition age >= 18 is true, so the message is printed.
If the condition is false, nothing happens—unless you add an else.

Adding an Else Block

Use else to tell the program what to do when the if condition is not true. 
int age = 16;

if (age >= 18) {
    System.out.println("You are an adult.");
} else {
    System.out.println("You are a minor.");
}
In this case, the program prints “You are a minor.” because age >= 18 is false.

Using Else If for Multiple Conditions

What if you want to check more than one condition? That’s where else if comes in.
Example: 
int score = 75;

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 {
    System.out.println("Grade: F");
}
This checks the conditions one by one until it finds one that’s true. In this case, since 75 is greater than 70, it prints “Grade: C”.

Important Rules to Remember

  • Java checks conditions from top to bottom.
  • Once it finds a true condition, it runs that block and skips the rest.
  • The else block is optional, but useful when you want to handle all other cases.
  • Curly braces {} are required for multiple statements, but optional for just one line (though still recommended).
Example without braces:
if (score > 50)
    System.out.println("Passed");
else
    System.out.println("Failed");
This works, but using braces makes your code easier to read and avoids mistakes: 
if (score > 50) {
    System.out.println("Passed");
} else {
    System.out.println("Failed");
}

Nested If-Else Statements

Sometimes, you might need to put one if inside another. This is called nesting.
Example: 
int age = 25;
boolean hasLicense = true;

if (age >= 18) {
    if (hasLicense) {
        System.out.println("You can drive.");
    } else {
        System.out.println("You need a license to drive.");
    }
} else {
    System.out.println("You are too young to drive.");
}
While nesting is useful, try not to go too deep—it can make your code harder to follow.

Real-World Example: Login Check

Here’s a simple example of how you might use if-else in a login system: 
String username = "admin";
String password = "1234";

if (username.equals("admin") && password.equals("1234")) {
    System.out.println("Login successful!");
} else {
    System.out.println("Invalid credentials.");
}
We use && to make sure both conditions are true.

Comparing If-Else to Switch (Bonus Tip)

Sometimes if-else chains can be replaced with a switch statement—for example, when comparing the same variable to different values.
But for range-based conditions (like scores or ages), if-else is the better choice.

Common Mistakes to Avoid

  • Forgetting the double equals (==): Use == to compare numbers, but use .equals() to compare strings.
  • Missing curly braces: This can lead to unexpected results, especially with more than one statement.
  • Wrong logic order: Always write the most specific conditions first to avoid incorrect matches.
Example of wrong order: 
if (score >= 70) {
    System.out.println("C");
} else if (score >= 90) {
    System.out.println("A");  // This will never run!
}

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