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Boolean Data Type in Java

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The boolean data type in Java is used to represent logical values with true and false. Learn about boolean literals, defining boolean variables, and operations that return a boolean result. Example programs and how to run them are included.

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Boolean Data Type in Java

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  1. The Boolean (logical) data type boolean

  2. 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

  3. Logical data type: boolean (cont.) • Encoding scheme used in the boolean data type: • uses 1 byte of memory (to store 0 or 1) • 0representstrue • 1representsfalse

  4. Boolean literals • There are 2 boolean literals (= logical constants) in Java: These 2 words are keywords (reserved words) in Java • true and, • false

  5. Defining boolean typed variables • Syntax to define an boolean typed variable: • Notes: • boolean NameOfVariable ; • The keywordboolean 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)

  6. Defining boolean typed variables (cont.) • 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 } }

  7. Defining boolean typed variables (cont.) • Example Program: (Demo above code) • Prog file: http://mathcs.emory.edu/~cheung/Courses/170/Syllabus/06/Progs/Boolean01.java • How to run the program:             • Right click on link and save in a scratch directory • To compile:   javac Boolean01.java • To run:          java Boolean01

  8. 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

  9. Operations that return a boolean result (cont.) • 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

  10. Operations that return a boolean result (cont.) • We will discuss the compare operatorsnext and discuss the logical operators after a few webpages.

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