Creating a Message Window

Question:
I have a note section on my Web page. I would like to be ableto click a radio button, and a small window with the note inside it wouldpop up. Can you help me?

Answer:
There are several ways to do this. At issue is what sort ofobject the message window should be. Four candidates suggest themselves:frame, dialog, text area, and canvas.The code below shows all four.

Note that the text area and canvas are confined to the viewing area of theirparent frame, while the dialog and frame are not. Also, only the dialogcan be made modal (i.e. unignorable).

Although the dialog implementation is probably the most standard, gettinga dialog box to appear inside an applet is awkward because a dialog must have aframe parent.

import java.awt.*;////////////////////////////////////////////////////////////////////class FrameMessage extends Frame {   private String msg; // message to be displayed   public FrameMessage(String s) {      setTitle(“A Message in a Frame”);      msg = s;   }   public boolean handleEvent(Event e) {      if(e.id == Event.WINDOW_DESTROY) dispose();      return super.handleEvent(e);   }   public void paint(Graphics g) {      g.drawString(msg, 20, 40);   }}////////////////////////////////////////////////////////////////////class DialogMessage extends Dialog {   private String msg; // message to be displayed   public DialogMessage(Frame parent, String s) {      super(parent, “A Message in a Dialog Box”, false);      msg = s;   }   public boolean handleEvent(Event e) {      if(e.id == Event.WINDOW_DESTROY && e.target == this) dispose();      return super.handleEvent(e);   }   public void paint(Graphics g) {      g.drawString(msg, 20, 40);   }}////////////////////////////////////////////////////////////////////class CanvasMessage extends Canvas {   private String msg; // message to be displayed   public CanvasMessage(String s) {      msg = s;      setBackground(Color.green);      resize(200, 300);   }   public void paint(Graphics g) {      g.drawString(msg, 20, 40);   }   // mouse events are always routed to canvasses!   public boolean mouseUp(Event e, int x, int y) {      hide();      return true;   }}////////////////////////////////////////////////////////////////////public class Msg extends Frame {   /* A radio button is a mutually exclusive checkbox; in other words,      a checkbox which when checked, automatically unchecks other      checkboxes in its group.   */   private Checkbox frameButton, dialogButton, textButton, canvasButton;   private CheckboxGroup buttons;   // our message   private String text = “A squid eating dough”;   // our message boxes   FrameMessage frameMsg;   DialogMessage dialogMsg;   TextArea textMsg;   CanvasMessage canvasMsg;   public Msg() {      setTitle(“Message Demos”);      setLayout(new FlowLayout());      buttons = new CheckboxGroup();      // radio buttons = grouped checkboxes      add(frameButton = new Checkbox(“Frame”, buttons, false));      add(dialogButton = new Checkbox(“Dialog”, buttons, false));      add(textButton = new Checkbox(“Text Area”, buttons, false));      add(canvasButton = new Checkbox(“Canvas”, buttons, false));   }   private void destroyAll() {      if (frameMsg != null) frameMsg.dispose();      if (dialogMsg != null) dialogMsg.dispose();      if (textMsg != null) textMsg.hide();      if (canvasMsg != null) canvasMsg.hide();   }   public boolean action(Event e, Object arg) {      if (e.target instanceof Checkbox)         if (frameButton.getState()) {            destroyAll();            frameMsg = new FrameMessage(text);            frameMsg.resize(300, 300);            frameMsg.show();         }         else if (dialogButton.getState()) {            destroyAll();            dialogMsg = new DialogMessage(this, text);            dialogMsg.resize(300, 300);            dialogMsg.show();         }         else if (textButton.getState()) {            destroyAll();            textMsg = new TextArea(text, 10, 20);            textMsg.setEditable(false);            add(textMsg);            show();         }         else if (canvasButton.getState()) {            destroyAll();            canvasMsg = new CanvasMessage(text);            add(canvasMsg);            canvasMsg.show();         }      return true;   }   public boolean handleEvent(Event e) {      if(e.id == Event.WINDOW_DESTROY && e.target == this)System.exit(0);      return super.handleEvent(e);   }   public static void main() {      Frame f = new Msg();      f.resize(600, 300);      f.show();   }}

Share the Post:
Share on facebook
Share on twitter
Share on linkedin

Overview

Recent Articles: