Moving Toward Object-Oriented Programming - Beginning Java Programming: The Object-Oriented Approach - page 116

➤

java.lang.System : Class providing system operations.

➤

java.lang.Math : Class providing methods to perform basic mathematics.

Other than this, this package also provides a number of classes to deal with complex Java aspects
such as reference management, reflection, and process spawning and control. All advanced concepts
which you can safely ignore for now.

The two classes that jump out, however, and that can be very useful are the Math and
StringBuilder classes.
Math contains two static constants ( E , the base of natural logarithms, and PI , the ratio of the cir-
cumference of a circle to its diameter), as well as a number of methods— abs , max , min , ceil , floor ,
sin , cos , tan , pow , and sqrt —to help out with mathematics when programming.

Mathematics in Java

try it out

Here is a short exercise to begin using mathematics in Java.
1.

Create a MathTester class in Eclipse with the following content:
class MathTester {
public static void main(String[] args) {
double num1 = 2.34;
double num2 = 1.56;

System.out.println(Math.max(num1, num2));
System.out.println(Math.min(num1, num2));
System.out.println(Math.sqrt(num1));
System.out.println(Math.pow(num1, num2));
}
}

2. Run the main method and observe the output.

How It Works

Now take a look at how it works.
1.

The Math class contains a number of methods to help out with mathematics when programming.
Take your time to explore other methods using Eclipse's context menu.

2.

Since the Math class belongs to the java.lang package, you do not need to write an import state-
ment but can use this class directly.

3.

All of Math 's methods are static , meaning that you do not have to create a Math object to be able
to use its methods. This is a common pattern for “utility” classes in Java, which are classes con-
taining a set of helpful grouped methods that can be statically accessed.

The StringBuilder class represents a mutable sequence of characters, compared to a normal String that
represents an immutable sequence of characters (which is why Java creates a new String object every
time you modify a String). The following Try It Out shows where the StringBuilder can be useful.