The if statement is an essential part of any program. With the if statement, you can set conditions for your program. The syntax and the diagram of the if statement look like this:

Main


              12345
            
if (condition) {
    // Code to be executed if the condition is true
} else {
    // Code to be executed if the condition is false
}

Below is a flowchart showing the use of an if statement. Before entering the if block, we check the condition. If the condition evaluates to true, we enter the if block and perform the necessary operations. If the condition evaluates to false, we skip the if block and continue with the code.

Let's look at an example with real values:

Main


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package com.example;

public class Main {
    public static void main(String[] args) {
        // You can change the values of variables `a` and `b' to test the `if` statements
        double a = 13.71;
        double b = 14.01;
        if (b > a) {
            System.out.println("b is greater than a");
        }
        if (a > b) {
            System.out.println("a is greater than b");
        }
    }
}

In this code, we establish a condition. If the value of a is greater than that of b, we display information about it. If the value of b exceeds a, we display different information about it.

if-else

But it doesn't look elegant when we have two separate if statements. We have a dedicated syntax for situations like this called the if-else statement.

Let's see how we can improve the code above using the if-else statement:

Main


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package com.example;

public class Main {
    public static void main(String[] args) {
        // You can change the values of variables `a` and `b' to test the `if` statements
        double a = 13.71;
        double b = 14.01;
        if (b > a) {
            System.out.println("b is greater than a");
        } else {
            System.out.println("a is greater than or equal to b");
        }
    }
}

We can see how we improved our previous code using the if-else statement. In simple terms, we check if the value of variable b is greater, and if the returned value is false, we enter the else block, where we display a different message.

Here is the block scheme of if-else Statement:

Let's examine a code fragment where we compare the values of two variables for equality:

Main


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package com.example;

public class Main {
    public static void main(String[] args) {
        // You can change the values of variables `a` and `b' to test the `if` statements
        int a = 10;
        int b = 10;
        if (a == b) {
            System.out.println("a equals b");
        } else {
            System.out.println("a is not equal to b");
        }
    }
}

Here, we are checking if the values of a and b are equal and displaying information about it. Since both a and b have a value of 10, the result will be true, so we display the corresponding message.

else-if chain

It is worth mentioning another statement called the else-if statement.

When we need to specify multiple different execution conditions, we can use the following syntax:

Main


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package com.example;

public class Main {
    public static void main(String[] args) {
        // You can change the values of variables `a` and test the `if-else` statement
        int a = 25;
        int b = 13;
        if (a > b) {
            System.out.println("a is greater than b");
        } else if (a == b) {
            System.out.println("a equals b");
        } else {
            System.out.println("b is greater than a");
        }
    }
}

In the code above, we can see that multiple different conditions are used. Thus, it follows a simple algorithmic chain. If the first condition is false, check the second one, and so on. We continue doing this until we get true, or if all conditions return false, we enter the familiar else block.

1. What is the result of this code?

2. What will be printed to console after code execution?

Everything was clear?

Thanks for your feedback!

Section 2. Chapter 5