Java Boolean

In Java, the boolean data type represents one of two possible values: true or false. It is a fundamental data type used to represent binary values or logical states, and is often used in conditional expressions, loops, and to control program flow based on conditions.

The Boolean type is used when we want to test a particular condition during the execution of the program.

All comparison operators return Boolean type values. Boolean values are often used in selection and iteration statements. The words true and false cannot be used as identifiers.

Notes:

1. The boolean type does not have a specific size defined by the language. However, it is typically stored using one bit of memory.
2. The default value of a boolean is false.

Basic Declaration and Initialization

You can declare a boolean variable and assign it either true or false:

public class BooleanExample {
    public static void main(String[] args) {
        boolean isCMotherLanguage= true;  // Declare and initialize boolean variable
        boolean isJavaOnlyFrontendLanguage = false;

        System.out.println("Is C Mother Language of Programming? " + isCMotherLanguage);  // true
        System.out.println("Is Java Frontend Language? " + isJavaOnlyFrontendLanguage );  // false
    }
}

Boolean use in Conditional Statements

boolean values are often used in conditional statements to decide the flow of execution.

public class BooleanExample {
    public static void main(String[] args) {
        boolean isAdmin = true;

        if (isAdmin) {
            System.out.println("You are admin.");
        } else {
            System.out.println("You are not admin.");
        }
    }
}

Output:

Boolean use with Comparison Operators

You can use comparison operators (like ==, !=, <, >, etc.) to generate boolean values based on conditions.

public class BooleanComparisonExample {
    public static void main(String[] args) {
        int a = 20;
        int b = 10;
        
        boolean result1 = a > b;    // true because 20 is greater than 10
        boolean result2 = a == b;   // false because 20 is not equal to 10
        
        System.out.println("Is a greater than b= " + result1);  // true
        System.out.println("Is a equal to b= " + result2);      // false
    }
}

Output:

Boolean use with Logical Operators

Logical operators like && (AND), || (OR), and ! (NOT) can be used to combine or negate boolean expressions.

public class BooleanLogicalExample {
    public static void main(String[] args) {
        boolean isUser = true;
        boolean isAdmin = false;

        // Using AND (&&) operator
        boolean checkANDCondition= isUser && isAdmin;
        System.out.println("Check (AND): " + checkANDCondition);  // false

        // Using OR (||) operator
        boolean checkORCondition = isUser || isAdmin;
        System.out.println("Check (OR): " + checkORCondition);  // true

        // Using NOT (!) operator
        boolean isNotAdmin = !isAdmin;
        System.out.println("Check (Not): " + isNotAdmin);  // true
    }
}