~cpp 
import javax.swing.JOptionPane;

public class HelloWorld {
	private String name;
	public HelloWorld() {
		name = "noname";
	}
	public void setName(String n)
	{
		name = n;
	}
	public void sayHello() {
		JOptionPane.showMessageDialog(null, "Hello, World!" + " " + name);	
	}
	public static void main(String[] args) {
		HelloWorld hello1 = new HelloWorld();
		hello1.setName("세환");
		hello1.sayHello();
		HelloWorld hello2;
		hello2 = hello1;
		hello2.sayHello();
	}
}

~cpp 
public class Point {
	private int x, y;

	public Point() {
	}

	public void setX(int xValue) { x = xValue; }
	public void setY(int yValue) { y = yValue; }
	public int getX() { return(x); }
	public int getY() { return(y); }

	public void move(int xValue, int yValue) {
	   x += xValue;
	   y += yValue;
	}
}

~cpp 
import javax.swing.*;

class Circle {
   private Point middlePoint = new Point();
   private int width;
   private int height;
   private String info = "";

   public Circle() {      
   }
   public void setData(int xValue, int yValue, int width, int height) {
	  middlePoint.setX(xValue);
	  middlePoint.setY(yValue);
	  this.width = width;
	  this.height = height;
   }
   public void setInfo() {
	  info += "Circle x : " + middlePoint.getX() + "\n" +
			  "Circle y : " + middlePoint.getY() + "\n" +
			  "Circle width : " + width + "\n" +
			  "Circle height : " + height + "\n";
   }

   public void draw() {
	  setInfo();
	  JOptionPane.showMessageDialog(null, info);
   }

   public void move(int xValue, int yValue) {
	  middlePoint.move(xValue, yValue);
   }
   public void change(int xValue, int yValue, int width, int height) {
	  move(xValue, yValue);
	  this.width = width;
	  this.height = height;
   }
}

~cpp 
import javax.swing.JOptionPane;

public class Line {
	private Point left_top = new Point();
	private Point right_bottom = new Point();
	private String info = "";

	public Line() {      
	}
	
	public void setData(int p1_x, int p1_y, int p2_x, int p2_y) {
	   left_top.setX(p1_x);
	   left_top.setY(p1_y);
	   right_bottom.setX(p2_x);
	   right_bottom.setY(p2_y);
	}
	
	public void setInfo() {
	   info += "직선" + "\n" +
			   "시작점의 x 좌표 : " + left_top.getX() + "\n" +
			   "시작점의 y 좌표 : " + left_top.getY() + "\n" +
			   "끝점의 x 좌표 : " + right_bottom.getX() + "\n" +
			   "끝점의 y 좌표 : " + right_bottom.getY() + "\n";
	}

	public void draw() {
	   setInfo();
	   JOptionPane.showMessageDialog(null, info);
	}

	public void move(int xValue, int yValue) {
	   left_top.move(xValue, yValue);
	   right_bottom.move(xValue, yValue);
	}
}

~cpp 
import javax.swing.JOptionPane;

public class Rectangle {
	private Point left_top = new Point();
	private Point right_bottom = new Point();
	private double area;
	private String info = "";

	public Rectangle() {      
	}
	
	public void setData(int p1_x, int p1_y, int p2_x, int p2_y) {
	   left_top.setX(p1_x);
	   left_top.setY(p1_y);
	   right_bottom.setX(p2_x);
	   right_bottom.setY(p2_y);
	   setArea();
	}
	
	public void setArea() {
		area = Math.abs(right_bottom.getX() - left_top.getX()) * Math.abs(left_top.getY() - right_bottom.getY());
	}
	
	public void setInfo() {
	   info += "사각형" + "\n" +
			   "left 좌표 : " + left_top.getX() + "\n" +
			   "top 좌표 : " + left_top.getY() + "\n" +
			   "right 좌표 : " + right_bottom.getX() + "\n" +
			   "bottom 좌표 : " + right_bottom.getY() + "\n" +
			   "area : " + area; 
	}

	public void draw() {
	   setInfo();
	   JOptionPane.showMessageDialog(null, info);
	}

	public void move(int xValue, int yValue) {
	   left_top.move(xValue, yValue);
	   right_bottom.move(xValue, yValue);
	}
}

~cpp 
class MyPictureFrame {
   private Circle circle = new Circle();
   private Line line = new Line();
   private Rectangle rect = new Rectangle();

   public MyPictureFrame() {
	  circle.setData(100,100,50,50);
	  circle.draw();
	  line.setData(12, 34, 56, 78);
	  line.move(100, 100);
	  line.draw();
	  rect.setData(100, 200, 300, 400);
	  rect.move(50, 50);
	  rect.draw();
   }
   public static void main(String[] args) {
	  MyPictureFrame frame = new MyPictureFrame();
   }
}