Working with Serialization
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class PersisTest extends JFrame implements ActionListener {
ArrayList displayList = new ArrayList();;
String pathname;
JButton clearBtn, saveBtn, restoreBtn, quitBtn;
public static void main(String args[]) {
if (args.length == 0) {
System.err.println("Usage: java PersisTest filename");
System.exit(-1);
}
new PersisTest(args[0]).show();
}
public PersisTest(String pathname) {
super("Save Me");
setDefaultCloseOperation(EXIT_ON_CLOSE);
this.pathname = pathname;
// Build the GUI. Make this object a listener for all actions.
JPanel pan = new JPanel();
clearBtn = new JButton("Clear");
clearBtn.addActionListener(this);
pan.add(clearBtn);
saveBtn = new JButton("Save");
saveBtn.addActionListener(this);
pan.add(saveBtn);
restoreBtn = new JButton("Restore");
restoreBtn.addActionListener(this);
pan.add(restoreBtn);
quitBtn = new JButton("Quit");
quitBtn.addActionListener(this);
pan.add(quitBtn);
Container c = getContentPane();
c.add(pan, BorderLayout.NORTH);
c.add(new ClickPanel(), BorderLayout.CENTER);
setSize(350, 200);
}
public void actionPerformed(ActionEvent e) {
if (e.getSource() == clearBtn) {
// Repaint with an empty display list.
displayList = new ArrayList();
repaint();
} else if (e.getSource() == saveBtn) {
// Write display list array list to an object output stream.
try {
FileOutputStream fos = new FileOutputStream(pathname);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(displayList);
oos.flush();
oos.close();
fos.close();
} catch (IOException ex) {
System.err.println("Trouble writing display list array list");
}
} else if (e.getSource() == restoreBtn) {
// Read a new display list array list from an object input stream.
try {
FileInputStream fis = new FileInputStream(pathname);
ObjectInputStream ois = new ObjectInputStream(fis);
displayList = (ArrayList) (ois.readObject());
ois.close();
fis.close();
repaint();
} catch (ClassNotFoundException ex) {
System.err.println("Trouble reading display list array list");
} catch (IOException ex) {
System.err.println("Trouble reading display list array list");
}
} else if (e.getSource() == quitBtn) {
System.exit(0);
}
}
class ClickPanel extends JPanel {
ClickPanel() {
MouseListener listener = new MouseAdapter() {
public void mousePressed(MouseEvent e) {
// Store x and y in display list array list.
Point p = new Point(e.getX(), e.getY());
displayList.add(p);
}
public void mouseReleased(MouseEvent e) {
// Store x and y in display list array list, and request
// repaint.
Point p = new Point(e.getX(), e.getY());
displayList.add(p);
repaint();
}
};
addMouseListener(listener);
}
public void paintComponent(Graphics g) {
// Clear to white.
g.setColor(Color.white);
g.fillRect(0, 0, getSize().width, getSize().height);
// Traverse display list, drawing 1 rect for each 2 points
// in the array list.
g.setColor(Color.black);
int i = 0;
while (i < displayList.size()) {
Point p0 = (Point) (displayList.get(i++));
Point p1 = (Point) (displayList.get(i++));
int x = Math.min(p0.x, p1.x);
int y = Math.min(p0.y, p1.y);
int w = Math.abs(p0.x - p1.x);
int h = Math.abs(p0.y - p1.y);
g.drawRect(x, y, w, h);
}
}
}
}
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