Getting to Know Java - Beginning Java Programming: The Object-Oriented Approach - page 23

table 2-4: Java Keywords

abstract continue for new switch

assert default goto package synchronized

boolean do if private this

break double implements protected throw

byte else import public throws

case enum instanceof return transient

catch extends int short try

char final interface static void

class finally long strictfp volatile

const float native super while

variables
As stated earlier, every class definition consists of both variables and methods. A variable is a name for a
memory location that stores a specific value. This value may change during program execution, which is
why it's called a “variable.” The BMICalculator class starts by defining the following variables:

// declare variables
double weight;
double height;
double BMI;

The weight , height , and BMI variables are defined using the data type double, which represents a
floating point number. Other data types exist in Java and will be covered in a subsequent section. In
Java, variables must always be defined in a class.

methods
As discussed earlier, a method is a piece of code within a class definition, and it performs a specific
kind of functionality. Just as with a class, every method definition is enclosed within brackets {...} .
In the BMICalculator example, three methods have been deined— BMICalculator , CalculateBMI,
and main . Consider the main method:

public static void main(String[] args) {
BMICalculator calculator = new BMICalculator(60, 1.70);
double bmi = calculator.calculateBMI();

// print BMI to screen
System.out.println("Your BMI is " + bmi + ".");
}