G.drawLine problem...

Question

I'm trying to make it so you click and option from the menu bar which will then open a JDialogBox, you enter text, it turns it into a string, then use g.drawline to ad it to the JPanel.
Heres my code:
// Scribble.java //
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
* This JFrame subclass is a simple "paint" application.
public class Scribble extends JFrame {   
   * The main method instantiates an instance of the class, sets it size, and
   * makes it visible on the screen
  public static void main(String[] args) {
    Scribble scribble = new Scribble();
    scribble.setSize(500, 300);
    scribble.setVisible(true);
  // The scribble application relies on the ScribblePane2 component developed
  // earlier. This field holds the ScribblePane2 instance it uses.
  ScribblePane2 scribblePane;
   * This constructor creates the GUI for this application.
  public Scribble() {
    super("Scribble"); // Call superclass constructor and set window title
    // Handle window close requests
    this.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
    // All content of a JFrame (except for the menubar) goes in the
    // Frame's internal "content pane", not in the frame itself.
    // The same is true for JDialog and similar top-level containers.
    Container contentPane = this.getContentPane();
    // Create the main scribble pane component,
    // a background color, and add it to the content pane
    scribblePane = new ScribblePane2();
    scribblePane.setBackground(Color.white);
    contentPane.add(scribblePane);
    // Create a menubar and add it to this window. Note that JFrame
    // handles menus specially and has a special method for adding them
    // outside of the content pane.
    JMenuBar menubar = new JMenuBar(); // Create a menubar
    this.setJMenuBar(menubar); // Display it in the JFrame
    // Create menus and add to the menubar
    JMenu filemenu = new JMenu("File");
    JMenu colormenu = new JMenu("Color");
    JMenu textmenu = new JMenu("Text");
    menubar.add(filemenu);
    menubar.add(colormenu);
    menubar.add(textmenu);
    // Create some Action objects for use in the menus and toolbars.
    // An Action combines a menu title and/or icon with an ActionListener.
    // These Action classes are defined as inner classes below.
    Action open = new OpenAction();
    Action save = new SaveAction();
    Action clear = new ClearAction();
    Action select = new SelectColorAction();
    Action text = new TextAction();
    // Populate the menus using Action objects
    filemenu.add(open);
    filemenu.add(save);
    filemenu.add(clear);
    colormenu.add(select);
    textmenu.add(text);
private final static int//initialization
                 CURVE = 0,
                 LINE = 1,
                 RECT = 2,             
                 OVAL = 3,              
                 ROUNDRECT = 4,         
                 FILLED_RECT = 5,
                 FILLED_OVAL = 6,
                 FILLED_ROUNDRECT = 7;
      Image OSI;  // The off-screen image (created in checkOSI()).
      int widthOSI, heightOSI;   
  private int mouseX, mouseY;   // The location of the mouse.
      private int begnX, begnY;     // The previous location of the mouse.
      private int startngX, startngY;   // The starting position of the mouse.
                                    // (Not used for drawing curves.)
      private boolean dragging;     // This is set to true when the user is drawing.
      private int shape;    // What type of figure is being drawn.  This is
                             //    specified by the shapeChoice menu.
      private Graphics dragGraphics;  // A graphics context for the off-screen image,
                                      // to be used while a drag is in progress.
      private Color dragColor;  // The color that is used for the shape that is
                                // being drawn.
      private void drawShape(Graphics g, int shape, int x1, int y1, int x2, int y2) {
           if (shape == LINE) {
               // For a line, just draw the line between the two points.
            g.drawLine(x1,y1,x2,y2);
            return;
         int x, y;  // Top left corner of rectangle that contains the figure.
         int w, h;  // Width and height of rectangle that contains the figure.
         if (x1 >= x2) {  // x2 is left edge
            x = x2;
            w = x1 - x2;
         else {          // x1 is left edge
            x = x1;
            w = x2 - x1;
         if (y1 >= y2) {  // y2 is top edge
            y = y2;
            h = y1 - y2;
         else {          // y1 is top edge.
            y = y1;
            h = y2 - y1;
         switch (shape) {   // Draw the appropriate figure.
            case RECT:
               g.drawRect(x, y, w, h);
               break;
            case OVAL:
               g.drawOval(x, y, w, h);
               break;
            case ROUNDRECT:
               g.drawRoundRect(x, y, w, h, 20, 20);
               break;
            case FILLED_RECT:
               g.fillRect(x, y, w, h);
               break;
            case FILLED_OVAL:
               g.fillOval(x, y, w, h);
               break;
            case FILLED_ROUNDRECT:
               g.fillRoundRect(x, y, w, h, 20, 20);
               break;
  //This inner class defines the "open" action to open an image file
  class OpenAction extends AbstractAction {
    public OpenAction() {
      super("Open");
    public void actionPerformed(ActionEvent e) {
      scribblePane.open();
//This inner class defines the "save" action to save as .jpg
  class SaveAction extends AbstractAction {
    public SaveAction() {
      super("Save As");
    public void actionPerformed(ActionEvent e) {
      scribblePane.save();
  /** This inner class defines the "clear" action that clears the scribble */
  class ClearAction extends AbstractAction {
    public ClearAction() {
      super("Clear"); // Specify the name of the action
    public void actionPerformed(ActionEvent e) {
      scribblePane.clear();
    //This inner class defines an Action that sets the current drawing color of
    //the ScribblePane2 component.
  class ColorAction extends AbstractAction {
    Color color;
    public ColorAction(Color color) {
    this.color = color;
    public void actionPerformed(ActionEvent e) {
      scribblePane.setColor(color); // Set current drawing color
   // This inner class defines an Action that uses JColorChooser to allow the
   // user to select a drawing color
  class SelectColorAction extends AbstractAction {
    public SelectColorAction() {
      super("Select Color...");
    public void actionPerformed(ActionEvent e) {
      Color color = JColorChooser.showDialog(Scribble.this,
          "Select Drawing Color", scribblePane.getColor());
      if (color != null)
        scribblePane.setColor(color);
  class TextAction extends AbstractAction {
    public TextAction() {
      super("Paste Text");
    public void actionPerformed(ActionEvent e) {
    scribblePane.text();
// A simple JPanel subclass that uses event listeners to allow the user to
// scribble with the mouse. Note that scribbles are not saved or redrawn.
class ScribblePane2 extends JPanel {
  public ScribblePane2() {
    // Give the component a preferred size
    setPreferredSize(new Dimension(450, 200));
    // Register a mouse event handler defined as an inner class
    // Note the call to requestFocus(). This is required in order for
    // the component to receive key events.
    addMouseListener(new MouseAdapter() {
      public void mousePressed(MouseEvent e) {
        moveto(e.getX(), e.getY()); // Move to click position
        requestFocus(); // Take keyboard focus
    // Register a mouse motion event handler defined as an inner class
    // By subclassing MouseMotionAdapter rather than implementing
    // MouseMotionListener, we only override the method we're interested
    // in and inherit default (empty) implementations of the other methods.
    addMouseMotionListener(new MouseMotionAdapter() {
      public void mouseDragged(MouseEvent e) {
        lineto(e.getX(), e.getY()); // Draw to mouse position
    // Add a keyboard event handler to clear the screen on key 'C'
    addKeyListener(new KeyAdapter() {
      public void keyPressed(KeyEvent e) {
        if (e.getKeyCode() == KeyEvent.VK_C)
          clear();
  /** These are the coordinates of the the previous mouse position */
  protected int last_x, last_y;
  /** Remember the specified point */
  public void moveto(int x, int y) {
    last_x = x;
    last_y = y;
  /** Draw from the last point to this point, then remember new point */
  public void lineto(int x, int y) {
    Graphics g = getGraphics(); // Get the object to draw with
    g.setColor(color); // Tell it what color to use
    g.drawLine(last_x, last_y, x, y); // Tell it what to draw
    moveto(x, y); // Save the current point
   * Clear the drawing area, using the component background color. This method
   * works by requesting that the component be redrawn. Since this component
   * does not have a paintComponent() method, nothing will be drawn. However,
   * other parts of the component, such as borders or sub-components will be
   * drawn correctly.
  public void open() { //Function to open file
    JFileChooser fileChooser = new JFileChooser(".");
    fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY); 
    int status = fileChooser.showOpenDialog(null);
      if (status == JFileChooser.APPROVE_OPTION) {
        File selectedFile = fileChooser.getSelectedFile();
  public void save() { //Function to save file [needs work]
    JFileChooser fileChooser = new JFileChooser(".");
      fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY); 
      int status = fileChooser.showSaveDialog(null);
        if (status == JFileChooser.APPROVE_OPTION) {
          File selectedFile = fileChooser.getSelectedFile();
  public void clear() {
    repaint();
  /** This field holds the current drawing color property */
  Color color = Color.black;
  /** This is the property "setter" method for the color property */
  public void setColor(Color color) {
    this.color = color;
  /** This is the property "getter" method for the color property */
  public Color getColor() {
    return color;
  public void text() {
    String inputValue = JOptionPane.showInputDialog("Enter yee olde string...");
    System.out.println("String entered is:" + inputValue);
  //  g.drawString(inputValue, startngX, startngY);
  //  String text = text.getText();
  public void paintComponent(Graphics g) {
         checkOSI();
         g.drawImage(OSI, 0, 0, this);
         if (dragging && shape != CURVE) {
            g.setColor(dragColor);
            drawShape(g,shape,startngX,startngY,mouseX,mouseY);
      private void checkOSI() {
         if (OSI == null || widthOSI != getSize().width || heightOSI != getSize().height) {
                // Create the OSI, or make a new one if panel size has changed.
            OSI = null;  // (If OSI already exists, this frees up the memory.)
            OSI = createImage(getSize().width, getSize().height);
            widthOSI = getSize().width;
            heightOSI = getSize().height;
            Graphics OSG = OSI.getGraphics();  // Graphics context for drawing to OSI.
            OSG.setColor(getBackground());
            OSG.fillRect(0, 0, widthOSI, heightOSI);
            OSG.dispose();
}when i try and do this:
  public void text(Graphics g) {
    String inputValue = JOptionPane.showInputDialog("Enter yee olde string...");
    System.out.println("String entered is:" + inputValue);
    g.drawString(inputValue, startngX, startngY);It says i can't put Graphics g there, not sure why :|
Any help would be great! Thanks :)

Answer 1

...alex wrote:
-Kayaman- wrote:
So you write the method to accept a Graphics object as a parameter, then you try to call it without passing a parameter.
GEE WIZ, I WONDER WHAT COULD BE THE PROBLEM?wow... thanks... that really helps me considering i'm posting in the "New To Java" section.Don't mention it.
>
As for the OSI = null, this is part of a group assignment. All the code between the /////////////'s is from another group member, i haven't even looked at the code yet as i just pasted it in and don't need to worry about it until i can get it the program to compile with drawLine.Well, you can get mental brownie points by telling him that it doesn't free any memory to explicitly assign it to null, especially since you're assigning it again on the next line.
There is almost never a need to explicitly set something to null like that.