JFrames
Some basic JFrame applications:
An empty frame
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.JComponent;
/**
* Write a description of class RectangleObject here.
*/
public class RectangleObject extends JComponent
{
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
// Construct a rectangle object
Rectangle box = new Rectangle(5, 10, 20, 30);
// draw the rectangle
g2.draw(box);
}
}
The JFrame class:
import javax.swing.JFrame;
/**
* Draw an empty frame using JFrame.
*
*/
public class RectangleJFrame
{
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setSize(300,400);
frame.setTitle("A Rectanlge Object in a JFrame");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
RectangleObject aRectangle = new RectangleObject();
frame.add(aRectangle);
frame.setVisible(true);
}
}
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.JComponent;
import java.awt.BasicStroke;
import java.awt.Color;
/**
* Write a description of class RectangleObject here.
*/
public class RectangleObject extends JComponent
{
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
// Construct a rectangle object
Rectangle box = new Rectangle(5, 10, 20, 30);
// draw the rectangle
g2.setColor(Color.red);
g2.setStroke(new BasicStroke(5));
g2.draw(box);
}
}
import javax.swing.JFrame;
/**
* Draw an empty frame using JFrame.
*
*/
public class RectangleJFrame
{
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setSize(300,400);
frame.setTitle("A Rectanlge Object in a JFrame");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
RectangleObject aRectangle = new RectangleObject();
frame.add(aRectangle);
frame.setVisible(true);
}
}
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import java.awt.Rectangle;
import javax.swing.JComponent;
/**
* Write a description of class EllipseObject here.
*/
public class EllipseObject extends JComponent
{
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
Rectangle box = new Rectangle(100, 100, 200, 200);
// draw the rectangle
g2.draw(box);
// Construct an Ellipse object
//Ellipse2D.Double circle = new Ellipse2D.Double(upperLeftXBox,upperLeftYBox , width, height);
Ellipse2D.Double circle = new Ellipse2D.Double(100, 100, 200, 200);
// draw the ellipse
g2.draw(circle);
}
}
import javax.swing.JFrame;
/**
* Draw an empty frame using JFrame.
*
*/
public class EllipseJFrame
{
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setSize(400,400);
frame.setTitle("An Ellipse Object in a JFrame");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
EllipseObject anEllipse = new EllipseObject();
frame.add(anEllipse);
frame.setVisible(true);
}
}
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import javax.swing.JComponent;
/*
A component that draws an alien face
*/
public class LotsOfColors extends JComponent
{
public void paintComponent(Graphics g)
{
// Recover Graphics2D
Graphics2D g2 = (Graphics2D) g;
// Draw the an ellipse
Ellipse2D.Double ellipse = new Ellipse2D.Double(150, 100, 100, 150);
g2.setColor(Color.YELLOW);
g2.draw(ellipse);
// Draw solid green rectangle
g2.setColor(Color.GREEN);
Rectangle box = new Rectangle(0, 0, 50, 50);
g2.fill(box);
box.translate(300, 300);
g2.fill(box);
// Draw the mouth
Line2D.Double line = new Line2D.Double(50, 50, 300, 300);
g2.setColor(Color.RED);
g2.draw(line);
// Draw the greeting
g2.setColor(Color.BLUE);
g2.drawString("Some colorful shapes", 100, 100);
}
}
import javax.swing.JFrame;
/**
* Draw an empty frame using JFrame.
*
*/
public class LotsOfColorsJFrame
{
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setSize(400,400);
frame.setTitle("Shapes with lots of colors in a JFrame");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
LotsOfColors colorfullObjects = new LotsOfColors();
frame.add(colorfullObjects);
frame.setVisible(true);
}
}
Drawing Geometric Shapes
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import javax.swing.JComponent;
/**
This component displays a circle that can be moved.
*/
public class ShapeComponent extends JComponent
{
private static final int SQUARE_X = 100;
private static final int SQUARE_Y = 100;
private static final int SQUARE_WIDTH = 50;
private static final int SQUARE_HEIGHT = 50;
private Ellipse2D.Double circle;
public ShapeComponent()
{
// The rectangle that the paintComponent method draws
circle = new Ellipse2D.Double(SQUARE_X, SQUARE_Y, SQUARE_WIDTH, SQUARE_HEIGHT);
}
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
g2.draw(circle);
}
/**
Moves the rectangle to the given location.
@param x the x-position of the new location
@param y the y-position of the new location
*/
public void moveTo(int x, int y)
{
circle = new Ellipse2D.Double(x, y, SQUARE_WIDTH, SQUARE_HEIGHT);
repaint();
}
}
import java.awt.event.MouseListener;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import java.awt.Color;
/**
This program displays a ShapeComponent.
*/
public class ShapeComponentViewer
{
private static final int FRAME_WIDTH = 300;
private static final int FRAME_HEIGHT = 400;
public static void main(String[] args)
{
final ShapeComponent component = new ShapeComponent();
// Add mouse press listener
class MousePressListener implements MouseListener
{
public void mousePressed(MouseEvent event)
{
int x = event.getX();
int y = event.getY();
component.moveTo(x, y);
}
// Do-nothing methods
public void mouseReleased(MouseEvent event) {}
public void mouseClicked(MouseEvent event) {}
public void mouseEntered(MouseEvent event) {}
public void mouseExited(MouseEvent event) {}
}
MouseListener listener = new MousePressListener();
component.addMouseListener(listener);
JFrame frame = new JFrame();
frame.getContentPane().setBackground(new Color(255, 0, 0));
frame.add(component);
frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
input and output with a GUI
import javax.swing.JOptionPane;
/**
* input and output with a GUI.
*/
public class InputPanel
{
public static void main(String[] args)
{
String input = JOptionPane.showInputDialog("Enter a number:");
int num = Integer.parseInt(input);
JOptionPane.showMessageDialog(null, "The number you entered is " + num);
}
}
Implementing the ActionLister with a Button
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
/**
An action listener that prints a message.
*/
public class ButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
System.out.println("You clicked me!!!!");
}
}
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
/**
This program demonstrates how to install an action listener.
*/
public class ButtonViewer
{
private static final int FRAME_WIDTH = 100;
private static final int FRAME_HEIGHT = 60;
public static void main(String[] args)
{
JFrame frame = new JFrame();
JButton button = new JButton("Click here if you dare!");
frame.add(button);
ActionListener listener = new ButtonListener();
button.addActionListener(listener);
frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
Using an Inner Class:
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
/**
This program demonstrates how to install an action listener.
*/
public class ButtonViewer
{
private static final int FRAME_WIDTH = 100;
private static final int FRAME_HEIGHT = 60;
public static void main(String[] args)
{
/************ Inner Class Define Before is used ***************************/
/**
An action listener that prints a message.
*/
class ClickListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
System.out.println("I was clicked.");
}
}
/************ Inner Class End ***************************/
JFrame frame = new JFrame();
JButton button = new JButton("Click me!");
frame.add(button);
ActionListener listener = new ClickListener();
button.addActionListener(listener);
frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
Motion effect
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.JComponent;
/**
This component displays a rectangle that can be moved.
*/
public class RectangleMovingComponent extends JComponent
{
private static final int BOX_X = 100;
private static final int BOX_Y = 100;
private static final int BOX_WIDTH = 20;
private static final int BOX_HEIGHT = 30;
private Rectangle box;
public RectangleMovingComponent()
{
// The rectangle that the paintComponent method draws
box = new Rectangle(BOX_X, BOX_Y, BOX_WIDTH, BOX_HEIGHT);
}
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
g2.draw(box);
}
/**
Moves the rectangle by a given amount.
@param x the amount to move in the x-direction
@param y the amount to move in the y-direction
*/
public void moveBy(int dx, int dy)
{
box.translate(dx, dy);
repaint();
}
}
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.Timer;
/**
This program moves the rectangle.
*/
public class RectangleMover
{
private static final int FRAME_WIDTH = 300;
private static final int FRAME_HEIGHT = 400;
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
frame.setTitle("An animated rectangle");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final RectangleMovingComponent component = new RectangleMovingComponent();
frame.add(component);
frame.setVisible(true);
class TimerListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
component.moveBy(1, 1);
}
}
ActionListener listener = new TimerListener();
final int DELAY = 100; // Milliseconds between timer ticks
Timer t = new Timer(DELAY, listener);
t.start();
}
}
Courtesy from Lachlan:
/* Lachlan McCarty
* 11-16-14
* 1.8.0_25
* LM_MovingCar.java
* Write a program, YI_MovingCar.java that animates a car
* so that it moves across a frame.
*/
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import javax.swing.JFrame;
import javax.swing.JComponent;
import javax.swing.Timer;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class LM_MovingCar {
private final int FRAME_WIDTH = 450;
private final int FRAME_HEIGHT = 100;
private final int DELAY = 100;
private final LM_MovingCarComponent component = new LM_MovingCarComponent();
private final JFrame frame = new JFrame();
public LM_MovingCar() {
frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
frame.setTitle("Moving Car");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(component);
frame.setVisible(true);
ActionListener listener = new LM_TimerListener();
Timer t = new Timer(DELAY, listener);
t.start();
}
public static void main(String[] args) {
new LM_MovingCar();
}
private class LM_TimerListener implements ActionListener {
public void actionPerformed(ActionEvent event) {
component.increaseCoor(1,0);
}
}
private class LM_MovingCarComponent extends JComponent {
private final int MULTIPLIER = 2; //ok to change
private int xpadding = 10; // ok to change
private int ypadding = 10; // ok to change
private int CAR_WIDTH = 60*MULTIPLIER; // do not change
private int CAR_HEIGHT = 40*MULTIPLIER; // do not change
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
// turn on antialiasing so it doesn't look like crap
RenderingHints rh = new RenderingHints(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.setRenderingHints(rh);
g2.drawRect(0*MULTIPLIER+xpadding,10*MULTIPLIER+ypadding,60*MULTIPLIER,10*MULTIPLIER);
g2.drawOval(10*MULTIPLIER+xpadding,20*MULTIPLIER+ypadding,10*MULTIPLIER,10*MULTIPLIER);
g2.drawOval(40*MULTIPLIER+xpadding,20*MULTIPLIER+ypadding,10*MULTIPLIER,10*MULTIPLIER);
g2.drawPolygon(new int[]{10*MULTIPLIER+xpadding,20*MULTIPLIER+xpadding,40*MULTIPLIER+xpadding,50*MULTIPLIER+xpadding},
new int[]{10*MULTIPLIER+ypadding,0*MULTIPLIER+ypadding,0*MULTIPLIER+ypadding,10*MULTIPLIER+ypadding}, 4);
}
public void increaseCoor(int x, int y) {
if (xpadding+x+CAR_WIDTH <= FRAME_WIDTH) xpadding += x;
if (ypadding+y+CAR_HEIGHT <= FRAME_HEIGHT) ypadding += y;
repaint();
}
}
}
Concepts and theory:
Java Applets: Frames and Panels
A frame is a container that is used to display GUI-based Java applications.
A frame is displayed as a separate window with its own title bar.
It can be repositioned on the screen and re-sized as needed by dragging it with the mouse.
It contains small buttons in the corner of the frame that allow the frame to be minimized, maximized, and closed.
A frame is defined by the JFrame class.
A panel is also a container. However, unlike a frame, it cannot be displayed on its own.
A panel must be added to another container for it to be displayed.
Generally a panel doesn’t move unless you move the container that it’s in.
Its primary role is to help organize the other components in a GUI.
A panel is defined by the JPanel class.
Java Applets: Components and Containers
A GUI component is an object that represents a screen element that is used to display information or to allow the user to interact with the program in a certain way.
A container is a special type of component that is used to hold and organize other components.
Frames and panels are two examples of Java containers.