boolean stores the result of a logical comparison and can take on one of two values:
Booleans were named after the nineteenth-century mathematician George Boole, who devised an arithmetic system based on the logic of true and false properties.
Booleans help us store a statement's truth or falsehood in a standard way. We evaluate true or false expressions everyday: "do I have my housekeys?" "Should I carry an umbrella?" "Have I called mom yet?"
Create a boolean by giving a boolean variable a true or false value:
boolean b = true; boolean c = (5 < 4); // c is false boolean e; // e doesn't yet have a value, but it's been initliazed
Two booleans are equal if they have the same value; that is, if they are both true or both false. For example:
true == true; // true false == true; // false false != true; // true
Suppose we have
int x = 4 and
int y = 12. What can we say about the following statements?
boolean b = x > y; // false, because 4 isn't larger than 12 boolean c = x == y; // false, because 4 isn't equal to 12 boolean d = y > x; // true, because 12 is greater than 4
Booleans can also be written with more complicated expressions:
boolean e = (20 - 10) > (9 * 1) // true boolean f = (39 - 30) * 9 != 81 // false