1. The Type boolean

2. Boolean Expressions and Boolean Variables  The type boolean is a primitive type  Variables of type boolean and Boolean expressions can have only values of either true or false.  Example: if (number > 0) System.out.println(“The number is positive.”); else System.out.println(“The number is negative or zero”);

3. Boolean Expressions and Boolean Variables (cont’d)  A Boolean variable can be given the value of a Boolean expression by using an assignment statement.  Example: int number = -5; boolean isPositive; isPositive = (number > 0);

4. Boolean Expressions and Boolean Variables (cont’d)  A value can also be assigned in the declaration statement. boolean isPositive = (number > 0);  The previous example can be rewritten as follows: if (isPositive) System.out.println(“The number is positive.”); else System.out.println(“The number is negative or zero”);

5. Naming Boolean Variables  When naming a Boolean variable choose a statement that will be true when the value of the Boolean expression is true.  Examples: boolean isPositive = (number > 0); boolean systemsAreOK = (temperature = 12000) && (cabinPressure > 30); boolean lightsOn = true;

6. Precedence Rules  First: the unary operators +, -, ++, --, and !  Second: the binary arithmetic operators *, /, %  Third: the binary arithmetic operators +, -  Fourth: the boolean operators, =  Fifth: the boolean operators ==, !=  Sixth: the boolean operator &  Seventh: the boolean operator ^  Eighth: the boolean operator |  Ninth: the boolean operator &&  Tenth: the boolean operator ||

7. Truth Table for the && (and) Boolean Operator Value of AValue of BResulting Value of A && B true false truefalse

8. Truth Table for the || (or) Boolean Operator Value of AValue of BResulting Value of A || B true falsetrue falsetrue false

9. Truth Table for the ^ ( exclusive or) Boolean Operator Value of AValue of BResulting Value of A ^ B true false truefalsetrue falsetrue false

10. Truth Table for the ! (not) Boolean Operator Value of AResulting Value of !A truefalse true

11. Input and Output of Boolean Values  The values true and false of the type boolean can be input and output the same way that values of the other primitive types  Example: boolean booleanVar = false; System.out.println(booleanVar); System.out.println(“Enter a boolean value:”); Scanner keyboard = new.Scanner(System.in); booleanVar = keyboard.nextBoolean(); System.out.println(“You entered “ + booleanVar);