The Boolean logical data type boolean Logical data
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
Logical data type: boolean (cont. ) • Encoding scheme used in the boolean data type: • 0 represents true • 1 represents false • 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 Name. Of. Variable ; • Notes: • The keyword boolean announces the variable definition clause • The Name. Of. Variable 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)
Defining boolean typed variables (cont. ) • Example: public class Boolean 01 { 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 } }
Defining boolean typed variables (cont. ) • Example Program: (Demo above code) – Prog file: http: //mathcs. emory. edu/~cheung/Courses/170/Syllabus/06/Progs/ Boolean 01. java • How to run the program: • Right click on link and save in a scratch directory • To compile: javac Boolean 01. java • To run: java Boolean 01
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
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
Operations that return a boolean result (cont. ) • We will discuss the compare operators next and discuss the logical operators after a few webpages.
- Slides: 10