// Examples of Class types: String, JFrame
JFrame mywindow;  // error: doesn't understand what JFrame is
import javax.swing.JFrame;
JFrame myWindow;
myWindow
myWindow = new JFrame();
myWindow
myWindow.setVisible(true); // method call
myWindow.setVisible(false); 
myWindow.setVisible(true);
myWindow.setTitle("This is my window.");
myWindow.setSize(400, 400);


// instruction: action to be performed
// Java statement: an instruction written in the Java language
// Java program: an organized collection of Java statements
// execute: follow the instructions
myWindow.getWidth()
myWindow.getHeight()
myWindow.getTitle()

// Three types of methods: functions, procedures, constructors
// function: returns data of a particular type
// procedure: perform a set of actions, but don't return any data
// constructor: functions that create the object and return it

JFrame w2 = new JFrame();
w2.setVisible(true);
w2.setTitle("Second window");
w2.setLocation(0, 500);
w2.setLocation(0, 5000);
w2.setLocation(0, 500);



//what if we want to customize JFrame?
// for example double the width&height of the window
//   or make the window a perfect square

OurJFrame ow = new OurJFrame();
ow.setVisible(true);
ow.setSize(100,300);
ow.doubleSize();  // method exists, 
//but it doesn't do anything yet
//let's implement it!
OurJFrame ow = new OurJFrame();
ow.setVisible(true);
ow.setSize(100,300);
ow.doubleSize();