1. Program: Shape Area
Print the area for various shape types using the respective formulas

2. Program details: getArea()
public double getArea()
This is a getter (or accessor) method that returns the area of a shape based on its current dimensions.
Since it is a getter, the method body must have a return statement (most likely at the end) that returns the requested values when the method is invoked.
E.g
public double getArea(){
return side1 * side1; }

3. Program details: setSide()
public void setSide(int newSide)
This is a setter(or mutator) method that sets the side property of a square
Since it is a setter, the method does not return a value, as such the method is declared void and the body does not contain a return statement
E.g.
public void setSide(int newSide){
side = newSide; }

4. Program details: Math.PI
The Math.PI constant is a value provided by Java to giv us the value of pi ( )
This means you don’t have to try and remember the value of pi, and you will always have the same value every time you use it
E.g.
Scanner keyboard = new Scanner(System.in); // Create a scanner object to get info from the keyboard
double radius = keyboard.getDouble(); // Get the user to enter a number for the radius
int circleArea = Math.PI * radius * radius; // Calculate the area of a circle using the entered value

5. Program details: JOptionPane
JOptionPane is a class that allows us to get input and output from the user using a Graphical User Interface (GUI)
The details of the class are available on Oracle’s official Java documentation:
showInputDialog()
This is a method of the JOptionPane class that allow us to get input from the user using a GUI
The method will return a String (a series of characters) even if the user enters a number
E.g.
String userInput = JOptionPane.showInputDialog(“Enter some information”): // Get data from user
System.out.println(userInput); // Print information to the screen

6. Program details: parseInt()
This is a method of the Integer class that will convert a String representation of digits into an integer
This method can be useful when using the showInputDialog() method of the JOptionPane class, because showInputDialog() always returns a string, even if the user enters numbers
E.g.
String userInput = JOptionPane.showInputDialog(“Enter a number for our calculation”);
int number = Integer.parseInt(userInput);
System.out.println( “Square of “ + number + “ is “ + (number * number));