Ad:

Java Discussion Thread
Marked Solved
Views: 985

Nov 7th, 2009

Blank JFrame

Expand Post »

Hi guys,
The following program works the way I want it to but there's one small problem; when it loads, it doesn't give a blank frame. It want it to show the output after I click on the blank area. Help me please.

Java Syntax (Toggle Plain Text)
import java.awt.*;
import javax.swing.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
 
public class TrackMouseMovementTest{
 
	public static void main(String[] args){
 
		EventQueue.invokeLater(new Runnable(){
			public void run(){
				MouseFrame frame = new MouseFrame();
				frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
				frame.setVisible(true);
			}
		});
	}
}
 
class MouseFrame extends JFrame
{
	public MouseFrame(){
	setTitle("Mouse Movement Tracker");
	setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
 
	MouseComponent component = new MouseComponent();
	add(component);
	}
	public static final int DEFAULT_WIDTH = 500;
	public static final int DEFAULT_HEIGHT = 500;
}
 
class MouseComponent extends JComponent{
	public MouseComponent(){
	    addMouseListener(new MouseHandler());
	}
 
	private class MouseHandler extends MouseAdapter{
		public void mousePressed(MouseEvent event){	
		  x = event.getX();
		  y = event.getY();
	      repaint();
		}
	}
		public void paintComponent(Graphics g){
	        g.drawString("X: " + x + ",Y: " + y + "",x,y);
	        g.drawString("Click #: " + counter ++ ,x , y + 16);
    } 
	int x;
	int y;  
	private static int counter=-1;
}
import java.awt.*;
import javax.swing.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

public class TrackMouseMovementTest{
	
	public static void main(String[] args){
		
		EventQueue.invokeLater(new Runnable(){
			public void run(){
				MouseFrame frame = new MouseFrame();
				frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
				frame.setVisible(true);
			}
		});
	}
}

class MouseFrame extends JFrame
{
	public MouseFrame(){
	setTitle("Mouse Movement Tracker");
	setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
	
	MouseComponent component = new MouseComponent();
	add(component);
	}
	public static final int DEFAULT_WIDTH = 500;
	public static final int DEFAULT_HEIGHT = 500;
}

class MouseComponent extends JComponent{
	public MouseComponent(){
	    addMouseListener(new MouseHandler());
	}
	
	private class MouseHandler extends MouseAdapter{
		public void mousePressed(MouseEvent event){	
		  x = event.getX();
		  y = event.getY();
	      repaint();
		}
	}
		public void paintComponent(Graphics g){
	        g.drawString("X: " + x + ",Y: " + y + "",x,y);
	        g.drawString("Click #: " + counter ++ ,x , y + 16);
    } 
	int x;
	int y;  
	private static int counter=-1;
}

Similar Threads

Just a blank screen = ( in Monitors, Displays and Video Cards
Passing data from one JFrame to another in Java
Need Help with JFrame in Java
having some trouble with my project in Java
new window in Internet Explorer is always blank in Web Browsers

babylonlion

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

19 posts
since Oct 2009

Permalink

Nov 7th, 2009

Re: Blank JFrame

Introduce own boolean flag 'pressed' and use it to switch needed behavior

quuba

Reputation Points: 123

Solved Threads: 106

Posting Pro

Offline

573 posts
since Nov 2008

Permalink

Nov 7th, 2009

Re: Blank JFrame

Don't paint when value of x & y variable is zero.

Java Syntax (Toggle Plain Text)
public void paintComponent(Graphics g){
  if(x>0 &&  y>0) {
     g.drawString("X: " + x + ",Y: " + y + "",x,y);
     g.drawString("Click #: " + counter ++ ,x , y + 16);
  }
}
public void paintComponent(Graphics g){
  if(x>0 &&  y>0) {
     g.drawString("X: " + x + ",Y: " + y + "",x,y);
     g.drawString("Click #: " + counter ++ ,x , y + 16);
  }
}

adatapost

Moderator

Reputation Points: 2136

Solved Threads: 1228

Posting Genius

Offline

6,527 posts
since Oct 2008

Permalink

Nov 7th, 2009

Re: Blank JFrame

As the previous poster said, use a boolean for first click, also increment your counter in mousePressed. If you increment it in paintComonent, counter will be incremented everytime the frame is repainted. For example when you resize your frame, your counter dramatically changes. This is the fixed code.

java Syntax (Toggle Plain Text)
import java.awt.*;
import javax.swing.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
 
public class TrackMouseMovementTest {
 
	public static void main(String[] args) {
 
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				MouseFrame frame = new MouseFrame();
				frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
				frame.setVisible(true);
			}
		});
	}
}
 
class MouseFrame extends JFrame {
	public MouseFrame() {
		setTitle("Mouse Movement Tracker");
		setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
 
		MouseComponent component = new MouseComponent();
		add(component);
	}
 
	public static final int DEFAULT_WIDTH = 500;
	public static final int DEFAULT_HEIGHT = 500;
}
 
class MouseComponent extends JComponent {
	public MouseComponent() {
		firstClick = false;
		addMouseListener(new MouseHandler());
	}
 
	private boolean firstClick;
 
	private class MouseHandler extends MouseAdapter {
		public void mousePressed(MouseEvent event) {
			x = event.getX();
			y = event.getY();
			counter++;
			firstClick = true;
			repaint();
		}
	}
 
	public void paintComponent(Graphics g) {
		if (firstClick) {
			g.drawString("X: " + x + ",Y: " + y + "", x, y);
			g.drawString("Click #: " + counter, x, y + 16);
		}
	}
 
	int x;
	int y;
	private static int counter = 0;
}
import java.awt.*;
import javax.swing.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

public class TrackMouseMovementTest {

	public static void main(String[] args) {

		EventQueue.invokeLater(new Runnable() {
			public void run() {
				MouseFrame frame = new MouseFrame();
				frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
				frame.setVisible(true);
			}
		});
	}
}

class MouseFrame extends JFrame {
	public MouseFrame() {
		setTitle("Mouse Movement Tracker");
		setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

		MouseComponent component = new MouseComponent();
		add(component);
	}

	public static final int DEFAULT_WIDTH = 500;
	public static final int DEFAULT_HEIGHT = 500;
}

class MouseComponent extends JComponent {
	public MouseComponent() {
		firstClick = false;
		addMouseListener(new MouseHandler());
	}

	private boolean firstClick;

	private class MouseHandler extends MouseAdapter {
		public void mousePressed(MouseEvent event) {
			x = event.getX();
			y = event.getY();
			counter++;
			firstClick = true;
			repaint();
		}
	}

	public void paintComponent(Graphics g) {
		if (firstClick) {
			g.drawString("X: " + x + ",Y: " + y + "", x, y);
			g.drawString("Click #: " + counter, x, y + 16);
		}
	}

	int x;
	int y;
	private static int counter = 0;
}

gangsta1903

Reputation Points: 12

Solved Threads: 8

Junior Poster

Offline

111 posts
since May 2008

Permalink

Nov 7th, 2009

Re: Blank JFrame

I appreciate the explanation ...that was very helpful

babylonlion

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

19 posts
since Oct 2009

Permalink

Nov 7th, 2009

Re: Blank JFrame

Thank you for the help

babylonlion

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

19 posts
since Oct 2009

This thread is solved

Either the thread starter or a moderator has marked this thread as solved. You can most likely trust the responses and answers given. There is most likely no reason for any further responses to be posted here. If you have a related question, please start a new thread in this forum instead.

This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

Previous Thread in Java Forum Timeline: Even Odd number synchronization using Threads

Next Thread in Java Forum Timeline: how to display private methods in javadoc?

DaniWeb Message

Cancel Changes

User Name
Password