Draw rectangle

Question

Hi,I want to use mouse to draw a rectangle.But my code doesn't work.Could anyone have a look and make it work please?Heaps of thanks!
import javax.swing.JInternalFrame;
import java.awt.Cursor;
import java.io.File;
//for inner class
import java.awt.event.MouseAdapter;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseEvent;
import java.awt.Point;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.Rectangle;
import java.awt.Color;
import java.awt.Container;
import javax.swing.JFrame;
* Testing drawing rectangle
public class TestDraw extends JInternalFrame
private Container c;
public TestDraw(String name) {
super(name,true,true,true,true);
//Set the window size or call pack...
setSize(300,300);
c = this.getContentPane();
c.setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
c.addMouseListener(new MouseMonitor(this));
setVisible(true);
}//End of constructor
public static void main(String[] args)
TestDraw td = new TestDraw("test");
     TestGUI tg = new TestGUI(td);
private static class TestGUI extends JFrame
     public TestGUI(JInternalFrame jif)
          setBounds(100,100,400,400);
          Container c = getContentPane();
c.add(jif);
setVisible(true);
/********************MouseMonitor INNER CLASS********************/
     private class MouseMonitor extends MouseAdapter
          private int clickedX,clickedY,releasedX,releasedY;
          private JInternalFrame j;
          public MouseMonitor(JInternalFrame ji)
this.j = ji;
          public void mouseClicked(MouseEvent event)
          clickedX = event.getX();
          clickedY = event.getY();
          }//End of mouseClicked()
          public void mouseReleased(MouseEvent event)
               releasedX = event.getX();
               releasedY = event.getY();
System.out.println("clickedX="+clickedX);
System.out.println("clickedY="+clickedY);
System.out.println("releasedX="+releasedX);
System.out.println("releasedY="+releasedY);
Node node = new Node(clickedX,clickedY,releasedX,releasedY);
node.setColor(Color.RED);
               j.paintComponent(node);
               j.repaint();
               j.validate();
/********************Node INNER CLASS********************/
class Node extends Rectangle
private Color color;
private int left, top, width, height;
public Node( int x, int y, int width, int height)
setBounds(x, y, width, height);
repaint();
void setColor(Color color) {
// Set the color of this shape
this.color = color;
public void setBounds(int left, int top, int width, int height) {
// Set the position and size of this shape.
this.left = left;
this.top = top;
this.width = width;
this.height = height;
void draw(Graphics g) {
g.setColor(color);
g.fillRect(left,top,width,height);
g.setColor(Color.black);
g.drawRect(left,top,width,height);
/**************************END INNER CLASS**********************/
          public void paint(Graphics g)
               Graphics2D g2 = (Graphics2D) g;
               g2.setPaint(Color.red);
               g2.draw3DRect(clickedX,clickedY,releasedX,releasedY,true);
}

Answer 1

Fabulous program!
I'd like to add more function,but stuck at the right click when the mouse pointing to the node.I want to show the popup menu when user right-clicks at the node,but show error message when he left-click(means he try to draw another node on the top of that node).
The program seems act properly when mouse is pressed,but error dialog pops and blocks the mouseReleased action.Thanks in advance!
import java.awt.Color;
import java.awt.Cursor;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JPanel;
import javax.swing.JOptionPane;
import javax.swing.JPopupMenu;
import javax.swing.JMenuItem;
public class ShapeFrame1 extends JInternalFrame {
     private List<Node> nodes;
     private Node selected;
     private Point start;
     private boolean drawing;
     public static void main(String[] args) {
          ShapeFrame1 sf = new ShapeFrame1("Shape Test");
          JFrame frame = new JFrame("Shape Test");
          frame.setBounds(100,100,640,480);
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.getContentPane().add(sf);
          sf.pack();
          sf.setVisible(true);
          frame.setVisible(true);
     public ShapeFrame1(String title) {
          super(title,true,true,true,true);
          setContentPane(new NodePanel());
          nodes = new ArrayList<Node>();
          getContentPane().addMouseListener(new MouseMonitor());
          getContentPane().addMouseMotionListener(new MouseMonitor());
     protected Node createNode(Point start, Point end) {
          return new Node(start.x, start.y,end.x - start.x, end.y - start.y, Color.BLACK);
     protected Node getNodeAt(Point location) {
          for(Node node : nodes)
               if(node.contains(location))
                    return node;
          return null;
     class NodePanel extends JPanel {
          public void paintComponent(Graphics g) {
               for(Node node : nodes)
                    node.paint(g);
               if(drawing) { // User is currently drawing
                    Graphics2D g2 = (Graphics2D)g;
                    g2.setColor(Color.BLUE);
                    g2.draw(createNode(start, getMousePosition()));
               else if (start != null){
     class Node extends Rectangle {
          private Color color;
          private String name;
          Node(int x, int y, int width, int height, Color color) {
               super(x, y, width, height);
               this.color = color;
          public void paint(Graphics g) {
               Graphics2D g2 = (Graphics2D)g;
               if(selected != null && selected.equals(this))
                    g2.setColor(Color.BLUE);
               else
                    g2.setColor(color);
               g2.draw(this);
          void setName(String n){
               this.name = n;
          String getName(){
               return this.name;
     class MyPopupMenu extends JPopupMenu{
          MyPopupMenu(){
               createDefaultMenuItem(this);
          private void createDefaultMenuItem(JPopupMenu popup) {
               JMenuItem item;
               item = new JMenuItem("cut");
               popup.add(item);
               item = new JMenuItem("copy");
               popup.add(item);
               item = new JMenuItem("paste");
               popup.add(item);
               popup.addSeparator();
               item = new JMenuItem("Add Node Name");
               popup.add(item);
     class MouseMonitor extends MouseAdapter implements MouseMotionListener {
          private MyPopupMenu popup = new MyPopupMenu();
          public void mousePressed(MouseEvent evt) {
               checkPopup(evt);
               Node node = getNodeAt(evt.getPoint());
                    if (node != null)
                         JOptionPane.showMessageDialog(
                               new JFrame(),
                          "Node exists.Please choose another location!",
                          "ERROR",
                          JOptionPane.ERROR_MESSAGE);
                    else
                         start = evt.getPoint();
          public void mouseReleased(MouseEvent evt) {
               checkPopup(evt);
               if(drawing) {
                    Node node = createNode(start, evt.getPoint());
                    nodes.add(node);
                    setCursor(Cursor.getDefaultCursor());
                    drawing = false;
               } else {
                    // User isn't drawing, so select a Node if there is one
                    Node node = getNodeAt(evt.getPoint());
                    selected = node;
               repaint();
          public void mouseMoved(MouseEvent evt) {}
          public void mouseDragged(MouseEvent evt) {
               drawing = true;
               setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
               repaint(); // User is currently drawing, so repaint the view
          private void checkPopup(MouseEvent evt){
               if (evt.isPopupTrigger()){
                    popup.show(evt.getComponent(),evt.getX(),evt.getY());
}