Telusko Docs

Conditional Statements in Java

Conditional statements allow a program to make decisions.
They enable Java to choose different paths of execution based on whether a condition is true or false.

Whenever you see an if statement, think of it as the program asking a yes/no question.
If the answer is “yes” (true), some code will run.
If the answer is “no” (false), another block of code may run instead.

if-else

General Form

if (condition) {
    // executes if condition is true
} else {
    // executes if condition is false
}

The condition must always evaluate to a boolean value.

Flowchart Representation

        [Condition?]
           /   \
        True    False
        /          \
 [Execute Block1]  [Execute Block2]

This flowchart shows how the program checks the condition and decides which block of code to execute.

Real-World Example – Car Speed

Imagine cruise control in a car:

If speed is above the limit → decrease speed
If speed is below the limit → increase speed
If speed is equal to the limit → maintain the speed

This is exactly how if-else works in real programs: different actions for different conditions.

Example 1 – Basic If

public class Demo {
    public static void main(String[] args) {
        int x = 18;
        if (x > 10) {
            System.out.println("Hello");
        }
    }
}

Explanation

The program checks whether x > 10.
Since 18 is greater than 10, the condition is true, and "Hello" is printed.
If the condition were false, nothing inside the block would execute.

Example 2 – If with Else

int x = 8;
if (x > 10 && x <= 20) {   // Valid range: 11 to 20
    System.out.println("Hello");
} else {
    System.out.println("Bye");
}

Understanding the Logic

If x lies between 11 and 20, print "Hello".
Otherwise, print "Bye".

Note:

if can exist on its own.
else must always be paired with an if.

Example 3 – Comparing Two Numbers

int x = 5;
int y = 7;

if (x > y) {
    System.out.println(x);
} else {
    System.out.println(y);
}

Output:

The larger number is printed based on the condition.

Example 4 – Braces Matter

Incorrect version:

if (x > y)
    System.out.println(x);
    System.out.println("Thank you"); // Always runs - NOT part of if
else
    System.out.println(y); // Error

This code fails because:

Without braces {}, Java treats only one line as part of the if.
"Thank you" always prints, even when x > y is false.
The else gets misaligned and causes a compilation error.

Correct version:

if (x > y) {
    System.out.println(x);
    System.out.println("Thank you");
} else {
    System.out.println(y);
}

Braces ensure both statements belong to the if block.

Key Notes

Java does not rely on indentation (unlike Python). Whether the code is indented or not, the compiler only follows braces {}.
Always use braces when you have more than one statement in a block.
Using braces even for a single statement improves clarity and reduces bugs.
if-else is the foundation of decision-making and will be used heavily in loops, validations, and algorithms.

Written By: Shiva Srivastava

If-Else