Java if then else Statement

What is an if-else Statement?

An if-else statement is a control flow statement that allows you to execute different blocks of code depending on whether a condition evaluates to ‘true’ or ‘false’. This enables you to build logic into your programs, making them more versatile and interactive

Syntax of If-Else Statements

The basic syntax of an if-else statement in Java looks like this:

if (condition) {
    // Code to execute if condition is true
} else {
    // Code to execute if condition is false
}

• 'condition': This is a boolean expression that evaluates to ‘true' or ‘false'.
• ‘//Code to execute if condition is true‘: This block of code runs if the condition evaluates to ‘true‘.
• ‘//Code to execute if condition is false‘: This block of code runs if the condition evaluates to 'false‘.

Example 1: Simple If-Else Statement

Let’s start with a basic example. Suppose you want to check if a number is positive or negative:

public class Main {

    public static void main(String[] args) {
    
        int number = 10;

        if (number > 0) {
            System.out.println("The number is positive.");
        } else {
            System.out.println("The number is negative or zero.");
        }
    }
}

In this example, if number is greater than 0, the program will print “The number is positive.” Otherwise, it will print “The number is negative or zero.”

Example 2: If-Else If-Else Ladder

Sometimes, you might need to evaluate multiple conditions. In such cases, you can use an if-else if-else ladder. This allows you to check several conditions in sequence:

public class Main {

    public static void main(String[] args) {
    
        int score = 85;

        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 if (score >= 60) {
            System.out.println("Grade: D");
        } else {
            System.out.println("Grade: F");
        }
    }
}

Here, the program checks the ‘score’ variable against multiple thresholds and prints the corresponding grade.

Combining Conditions

C# provides the ability to combine multiple conditions by using logical operators like this:

• ‘&&' (AND): True if both conditions are true.
• ‘||‘ (OR): True if at least one condition is true.
• ‘!‘ (NOT): True if the condition is false – in other words, if condition is ‘false’ then execute the block of code .

Here’s an example combining conditions:

int age = 19;
boolean hasTicket = true;

if (age >= 18 && hasTicket)
{
    Console.WriteLine("You can enter the event.");
}
else
{
    Console.WriteLine("You cannot enter the event.");
}

In this case, a person can enter the event only if they are 18 or older and have a ticket.

* Remember: if you use multiple ‘else if’ in the case like above, whichever condition is true, only that block of code will be executed and the system will skip the rest of the ‘else if ‘ checkpoints: let’s break it down to see how it works: in the example above, first piece of if statement will be checked, and will return false, because score is not 90 or greater, then the first ‘else if’ will be checked and will return ‘true’ because the score is greater than 80 user will get output of ‘Grade B’ and after that point the system will skip the rest of ‘else if’.