---

The Boolean (logical) data type boolean

---

• Logical data type: boolean
  • The boolean data type:

    is a built-in (primitive) data type of Java is used to represent the logical values There are 2 logical values: true false          Encoding scheme used in the boolean data type: 0 represents false 1 represents true uses 1 byte of memory (to store 0 or 1)

  ---

  ---

• Boolean literals
  • There are 2 boolean literals (= logical constants) in Java:

    true   and, false

    These 2 words are keywords (reserved words) in Java

  ---

  ---

• Defining boolean typed variables

  • Syntax to define an boolean typed variable:

    boolean NameOfVariable ;

    Notes:

    The keyword boolean announces the variable definition clause The NameOfVariable is an identifier which is the name of the variable. The variable definition clause is must be ended with a semi-colon ";" A boolean typed variable can store true (1) or false (0)

  • Example:

    public class Boolean01 { public static void main(String[] args) { boolean a; // boolean typed variable a = true; System.out.println(a); // prints true a = false; System.out.println(a); // prints false a = (3 > 1); // 3 > 1 evals to true, so: a = true System.out.println(a); // prints true a = (3 <= 1); // 3 <= 1 evals to false, so: a = false System.out.println(a); // prints false } }

    ---

  • Example Program: (Demo above code)                                                
    • Prog file: click here

    How to run the program:

    Right click on link and save in a scratch directory To compile:   javac Boolean01.java To run:          java Boolean01

  ---

  ---

• Operations that return a boolean result
  • There are 2 types of operators that return a boolean result (true or false):

    Compare operators: A compare operator compares 2 numerical expressions and return a Boolean result. Example: the compare operation 3 > 1 returns the Boolean value true Logical operators: A logical operator compares 2 Boolean (logical) expressions and return a Boolean result. Example: the logical operation true AND false returns the Boolean value false

    ---

  • We will discuss the compare operators next and discuss the logical operators after a few webpages.