Java If Statement - Syntax, Flowchart and Examples

⏱️ 7 min read • Beginner Level • Lesson 21

The if statement in Java is used to execute a block of code only when a specified condition is true. It is one of the most basic and important decision-making statements in Java programming.

Before learning the if statement, you should understand Java operators, Java data types, and Java variables.

Decision Making in Java

Many times, we want a set of instructions to execute only in a particular situation. For example, if a student gets marks greater than or equal to 33, we may want to print "Pass". Otherwise, we may print something else.

This kind of logic is handled using decision control statements. In decision-making, Java checks a condition and executes code based on whether the condition evaluates to true or false.

Real World Examples of if Statement

Types of Conditional Statements in Java

Java supports multiple decision-making statements. Each one is used for a different type of condition-based logic.

What is if Statement in Java?

The if statement checks a boolean condition. If the condition is true, the code inside the if block is executed. If the condition is false, the block is skipped.

Syntax of if Statement

if (condition) {
    // statements execute only if condition is true
}

public class IfExample {
    public static void main(String[] args) {

        int marks = 70;

        if(marks >= 33) {
            System.out.println("Pass");
        }
    }
}    

Output: Pass

The above code prints Pass if the marks are greater than or equal to 33.

Flowchart of if Statement

The following diagram shows how an if statement works. Java first checks the condition. If it is true, the if block executes. Otherwise, the block is skipped.

Execution flow of Java if statement

Java if Statement Example

The following program checks whether the value of a is less than 20. Since the condition is true, the message inside the if block is printed.

public class IfStatementExample {
    public static void main(String[] args) {
        int a = 10;

        if (a < 20) {
            System.out.println("a is less than 20");
        }

        System.out.println("value of a is: " + a);
    }
}

Output:

a is less than 20
value of a is: 10

Explanation of the Program

Another Example: Check Passing Marks

Here is another simple example that checks whether a student has passed based on marks.

public class PassCheckExample {
    public static void main(String[] args) {
        int marks = 75;

        if (marks >= 33) {
            System.out.println("You passed the exam.");
        }

        System.out.println("Program completed.");
    }
}

Output:

You passed the exam.
Program completed.

Common Mistakes with if Statement

Mistake: Semicolon after if condition

public class IfSemicolonMistake {
    public static void main(String[] args) {
        int marks = 20;

        if (marks >= 33); {
            System.out.println("This line runs because of the unwanted semicolon.");
        }
    }
}

Interview Questions ⭐

🧠 Test your understanding with a quick quiz

int marks = 25;
if (marks >= 33) {
    System.out.println("Pass");
}
System.out.println("Result checked");

int number = 50;
if (number > 10);
{
    System.out.println("Inside block");
}

int x = 10;
if (x = 10) {
    System.out.println("Hello");
}

int a = 10;
if (a < 20) {
    System.out.println("a is less than 20");
}
System.out.println("Done");

🎉 Great job! Continue learning Java step by step.