If Statement Java: Syntax, Flowchart, and Practical Examples

In the world of programming, decision-making is crucial. It allows programmers to control the flow of execution within a program. In Java, the if statement is a fundamental tool for decision-making, enabling the program to execute specific code blocks based on certain conditions.

What is an if Statement?

if statement is a control flow statement. If the specified condition is true then only the block of if statement will be executed.

Suppose the condition is false then a block of if statement or body of if statement will not execute and control is transferred to the next statements.

Syntax

if (condition) {
    // if the condition is true
    // this block will be executed
}

Flowchart

Explanation

Let’s understand if statement working with the help of a flowchart. First control start and go towards if condition and then the condition is checked if the condition is false then the body of if means “if block in the flowchart” will not execute and control transferred to the “Statement after If block in the flowchart”.

Another case is if the condition is true then “if block in the flowchart” will execute and after execution is complete, control is transferred to the “Statement after If block in the flowchart”.

Types of conditions

Let’s talk about conditions, 3 types of conditions are used with if blocks.

1. Boolean Expression: In this, the condition itself is a boolean value.

boolean isRaining = true;
if (isRaining) {
    System.out.println("Yes! It is raining.");
}

In this code, the variable name is isRaining of boolean data type and the value is true. The condition is checked, and the condition is true so this line of code “System.out.println("Yes! It is raining.");” will be executed and the message “Yes! It is raining.” print on the console.

Yes! It is raining.

2. Comparison Operators: In this, comparison operators are used in condition.

• == checks for equality.
• != checks for inequality.
• >, <, >=, <= compare numerical values.

int age = 20;
if (age >= 18) {
    System.out.println("You are an adult.");
}

In this code, if a variable age is greater or equal to the value 18 then the message “You are an adult.” will be printed on the console.

You are an adult.

3. Logical Operators: With the help of logical operators we can combine two conditions in if statement.

&& (AND), || (OR), ! (NOT)

int score = 75;
if (score >= 70 && score < 80) {
    System.out.println("Your grade is B.");
}

In this code, if the score value is between or equal to 70 and 80 then the output will be “Your grade is B.“

Program Example

public class IfStatementExample {

    public static void main(String[] args) {
        // Example age to check
        int age = 16;

        // Check if the person is an adult
        if (age > 18) {
            System.out.println("Person is an adult with age " + age);
        }

        // Check if the person is a teenager
        if (age >= 13 && age <= 18) {
            System.out.println("Person is a teenager with age " + age);
        }

        // Check if the person is younger
        if (age < 13) {
            System.out.println("Person is younger with age " + age);
        }
    }
}

Explanation

1. Adult Check:
   • if (age > 18) checks if the age is greater than 18, and prints that the person is an adult.
2. Teenager Check:
   • if (age >= 13 && age <= 18) checks if the age is between 13 and 18, inclusive, and prints that the person is a teenager.
3. Younger Check:
   • if (age < 13) checks if the age is less than 13, and prints that the person is younger.

How It Works

• Adult: The program will print “Person is an adult with age 16” only if the age is greater than 18.
• Teenager: The program will print “Person is a teenager with age 16” if the age is between 13 and 18.
• Younger: The program will print “Person is younger with age 16” if the age is less than 13.

Now the question is what is the output of this program, our variable age is 16 in the program above. so,

• age > 18: The condition is false because 16 is not greater than 18.
• age >= 13 && age <= 18: The condition is true because 16 is between 13 and 18, inclusive. Thus, it prints “Person is a teenager with age 16”.
• age < 13: The condition is false because 16 is not less than 13.

Output

Person is a teenager with age 16

Tip: Using if Statements Without Curly Braces in Java

In Java, you can technically use if statements without curly braces {} when the statement following the if is a single line. For example:

if (condition)
    System.out.println("Fun with java");

Advantages:

• Conciseness: Omitting curly braces can make your code look cleaner and more compact when dealing with single-line statements.

Limitations:

• Readability: Without curly braces, it might not be immediately clear which statements are associated with the if condition, especially in more complex code.
• Maintenance: Adding additional statements later can lead to bugs. For example, consider the following code:

if (condition)
    System.out.println("Fun with java");
    System.out.println("This line will always execute.");

Here, only the first println statement is part of the if block. The second println is always executed, which might not be the intended behavior.

Best Practices: For clarity and to avoid accidental errors, it’s often recommended to use curly braces {} even for single-line statements:

if (condition) {
    System.out.println("Fun with java");
}

This practice helps ensure that all intended statements are included in the if block and makes your code easier to read and maintain.

Conclusion

The if statement in Java helps your program make decisions. It lets you run certain code only when specific conditions are true. By using if statements, you can make your Java programs smarter and more flexible. Practice using them to handle different situations in your code. With time, you’ll become more confident and skilled in Java programming!

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• If Else in Java – Dive into the If Else statement and understand its practical uses.
• If Else If in Java – Explore the basics of the If Else If and how to implement it effectively.

Feel free to explore these articles to enhance your understanding of Java programming!

Additional Resources

To deepen your understanding of the If statement in Java, check out the official Java Documentation on Control Flow Statements provided by Oracle. This resource offers a comprehensive overview of Java’s control flow statements, including detailed explanations and examples.