If

A school program needs reliable data and clear rules. An if statement runs its block only when a boolean condition is true. Use it when a school action is optional, such as congratulating a passing student.

The if statement in Java is like a gate. It opens only if a certain condition is true. Otherwise, it quietly ignores the code block inside it. This simple control structure forms the basis for decision-making in Java programs.

if (condition) {
    // code to execute if condition is true
}

The condition must evaluate to a boolean value, either true or false. If it's true, the code inside the block executes. If not, the program simply skips that block and moves on.

Use case: A software engineer is developing a system that checks a student's test score. If the score is greater than 5, the system should acknowledge that the student has passed the minimum benchmark.

Program description: In this Java program, we simulate a scenario where a student's test score is stored in the variable x. Let us assume that the value in x is set to 10 for this run. In real-time, we may get the value for x as input from the user. The if statement checks whether the score is greater than 5. If this condition is true, the program prints a message indicating that the score is above the benchmark. Regardless of the condition, the program ends with a general message indicating completion.

public class IfExample1 {
    public static void main(String[] args) {
        int score = 10;
        if (score > 5) {
            System.out.println("score is greater than 5");
        }
        System.out.println("Program ended.");
    }
}

score is greater than 5
Program ended.

Explanation:

Since x > 5 evaluates to true, the message inside the if block is printed. The final statement runs regardless of the condition.

public class IfExample2 {
    public static void main(String[] args) {
        int age = 15;
        if (age >= 18) {
            System.out.println("You can vote.");
        }
        System.out.println("Check completed.");
    }
}

Check completed.

Explanation:

Here, the condition age >= 18 is false. So, the code inside the if block is ignored. Only the final line runs.

• Always ensure your condition is boolean: Non-boolean conditions won't compile in Java.
• Use braces { } even for single-line blocks: It improves readability and helps avoid logical bugs.
• Keep your conditions clear and readable: Use meaningful variable names and avoid overly complex expressions.

• Using = instead of ==: Assignment vs. comparison. if (a = 10) is invalid. Use == for comparison.
• Forgetting curly braces: Without them, only the next line is considered part of the if block.
• Writing semicolon after if condition: if (x > 0); { ... } causes logic errors. That semicolon ends the if prematurely.

public class IfExample3 {
    public static void main(String[] args) {
        int marks = 45;
        if (marks > 50)
            System.out.println("You passed!");
            System.out.println("This message is outside the if.");
    }
}

This message is outside the if.

Explanation:

Only the first print statement is inside the if. The second line executes every time. To avoid such surprises, always use curly braces.

The Java if statement allows your programs to make decisions. Always test your conditions, keep your code readable, and avoid syntax pitfalls. As you progress, if will serve as a foundation for more advanced constructs like else, else if, and switch statements.

The statement after the block runs regardless of the condition. Braces make the intended boundary visible.

Before running this Java program, write down each line you expect to see. Identify the value, branch, object or exception responsible for each line. Then explain whether the following assumption is valid: The statement after the block runs regardless of the condition.

Java 17 · Main.java · complete practice program

public class Main  {
  public static void main(String[] args)  {
    int marks = 72;
    if (marks >= 50)  {
      System.out.println("Pass");
    }
    System.out.println("Report ready");
  }
}

Now change one thing: Change marks to 40. Predict the new behavior before checking the worked variation.

Java 17 · Main.java · source repeated for this answer

public class Main  {
  public static void main(String[] args)  {
    int marks = 72;
    if (marks >= 50)  {
      System.out.println("Pass");
    }
    System.out.println("Report ready");
  }
}

Expected output

Pass
Report ready

An if statement runs its block only when a boolean condition is true. Use it when a school action is optional, such as congratulating a passing student.

The statement after the block runs regardless of the condition. Braces make the intended boundary visible.

Run with javac Main.java, then java Main. The declaration of Main names the class; main starts the example, and println writes a complete output line.

Worked variation: Change marks to 40. The Pass line is skipped, but Report ready is still printed.

An if statement runs its block only when a boolean condition is true. Use it when a school action is optional, such as congratulating a passing student. The statement after the block runs regardless of the condition. Braces make the intended boundary visible.

Related explanations: Java Variables, Java Class - Blueprint of Objects, Exceptions in Java Introduction.

Supporting documentation: Official Java learning guide and Java 17 language specification.