I am new to java, I wanted to make a program that draws a box on screen, everything is correct except for the paintComponent(); which is not working
import java.awt.*;
import javax.swing.*;
import java.awt.Graphics2D.*;
public class Frame extends JPanel
{
#Override //this section creates the box
public void paintComponent(Graphics g){
Graphics2D g2 = (Graphics2D) g;
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.drawRect(150,150,20,20);
}
public static void createWindow() //this section creates the frame
{
JFrame frame = new JFrame("Simple GUI");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //set closing bebavior
frame.setSize(400, 400); //set the size of jframe
frame.setLocationRelativeTo(null); //center the jframe
frame.setVisible(true); //show the frame
}
//main method
public static void main(String[] args)
{
createWindow();//launch your creaWindow method
paintComponent();
}
}
You have to review the basics of Java. Your mistake in this is that you have to create an object of this class Frame and add it to the JFrame which you have created. Below is the correct code #Hh000.
import java.awt.*;
import javax.swing.*;
import java.awt.Graphics2D.*;
public class Frame extends JPanel{
#Override //this section creates the box
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.BLACK);
g.drawRect(150,150,20,20);
}
//main method
public static void main(String[] args){
JFrame frame = new JFrame("Simple GUI");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //set closing bebavior
Frame frameObject = new Frame(); //Making a class object
frame.add(frameObject); //Adding the object into the JFrame
frame.setSize(400, 400); //set the size of jframe
frame.setLocationRelativeTo(null); //center the jframe
frame.setVisible(true);
}
}
Related
So I am new in java graphics and I am creating a program that will show a rectangle. But when I run my program it only show like a small box and not the rectangle. I don't really know why it is happening.
Here is my code:
import javax.swing.*;
public class GraphicsEditor{
public static void main(String[] args) {
JFrame frame = new JFrame();
JPanel panel = new JPanel();
Rectangle rectangle = new Rectangle();
frame.setSize(1280, 720);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.add(panel);
panel.add(rectangle);
}
}
This is my rectangle class:
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JPanel;
public class Rectangle extends JPanel implements Shape {
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2D = (Graphics2D) g;
g2D.fillRect(0, 0, 200, 130);
}
}
This is my shape interface:
import java.awt.*;
public interface Shape {
void paintComponent(Graphics g);
}
Here, try this
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.LineBorder;
public class GraphicsEditor {
public static void main(String[] args) {
JFrame frame = new JFrame();
Rectangle rectangle = new Rectangle();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(rectangle);
frame.pack();
// center frame on screen
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
class Rectangle extends JPanel {
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2D = (Graphics2D) g;
g2D.fillRect(0, 0, 200, 130);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(500, 500);
}
}
A couple of things.
you don't need the interface.
unlike components, just painting a picture doesn't affect the layout manager, so the panel will be reduced to it's default size with out regard to any painting.
so you need to override getPreferredSize() in your JPanel.
As the comments said, you should set the preferred size of both your panel and rectangle to your desired size, and then pack the frame, like:
panel.setPreferredSize(new Dimension(500,500));
rectangle.setPreferredSize(new Dimension(500,500));
frame.pack();
Otherwise your LayoutManager (when not specified it defaults to FlowLayout) will handle your rectangle the way it wants. So another way would be learning about Layout Managers, and using your desired one.
As a side note, I would like to make some suggestions to your code. Remember, Swing is not thread safe, so place your code inside an invokeLater() call, such as:
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
JPanel panel = new JPanel();
Rectangle rectangle = new Rectangle();
frame.setSize(1280, 720);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
panel.setPreferredSize(new Dimension(500,500));
rectangle.setPreferredSize(new Dimension(500,500));
frame.add(panel);
panel.add(rectangle);
frame.pack();
frame.setVisible(true);
}
});
Also, calling frame.setVisible(true) should be called after adding your components.
I'm building a PongClone but I encounter a bug. **I think the bug is cause by JPanel.
I tried the Image instead of BufferedImage.
I tried the drawImage outside the paintComponent method.
I create to another panel and then add that panel inside a mainpanel.
Menu Class
package me.pong;
import javax.swing.*;
public class TestMenu {
JFrame frame;
public void createFrame () {
TestMain main = new TestMain ();
frame = new JFrame("TEST");
frame.setSize (800, 450);
frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
frame.getContentPane ().add (main.panel);
frame.setVisible (true);
}
}
MainClass
package me.pong;
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;
public class TestMain extends JPanel {
JPanel panel = new JPanel ();
BufferedImage img;
Graphics g;
public static void main (String[] args) {
TestMain testMain = new TestMain ();
TestMenu menu = new TestMenu ();
menu.createFrame ();
testMain.drawGraphics ();
}
public void drawGraphics(){
panel.add (new TestMain ());
img = new BufferedImage(800, 450, BufferedImage.TYPE_INT_RGB);
g = img.createGraphics ();
g.drawString ("TEST STRING 2", 250,250);
}
#Override
protected void paintComponent (Graphics g) {
super.paintComponent (g);
g.clearRect (0,0,800,450);
g.drawImage (img, 0,0,null);
g.setColor (Color.white);
g.drawString ("TEST STRING", 500,250);
g.setColor (Color.black);
g.drawRect (150,100,10,70);
}
}
I expect the Image fill the component but actual output is little tiny box.
Just like that
EDIT: Delete the code and added MCVE/SSCCE Code(I didn't know that). Still same. If I add the image inside the frame it's works but other way doesn't. I know I'm missing something, but I don't know what that is.
**Yes. Problem caused by JPanel but I don't know how to fix it.
The extra panel declared within the custom painted class that is a panel was not only unnecessary, but the source of problems. See further comments in code.
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;
public class TestMain extends JPanel {
JFrame frame;
// Not needed or useful!
//JPanel panel = new JPanel();
BufferedImage img;
Graphics g;
public static void main(String[] args) {
TestMain testMain = new TestMain();
testMain.createFrame();
testMain.drawGraphics();
}
public void createFrame() {
TestMain main = new TestMain();
frame = new JFrame("TEST");
frame.setSize(400, 250);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//frame.getContentPane().add(main.panel);
frame.getContentPane().add(main);
frame.setVisible(true);
}
public void drawGraphics() {
//panel.add(new TestMain());
add(new TestMain());
img = new BufferedImage(800, 450, BufferedImage.TYPE_INT_RGB);
g = img.createGraphics();
g.drawString("TEST STRING 2", 250, 250);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.clearRect(0, 0, 800, 450);
// all JComponent instances are image observers
//g.drawImage(img, 0, 0, null);
g.drawImage(img, 0, 0, this);
g.setColor(Color.WHITE);
// NEW! Otherwise invisible
g.setColor(Color.RED);
g.drawString("TEST STRING", 200, 100);
g.setColor(Color.BLACK);
g.drawRect(150, 100, 10, 70);
}
}
As an aside:
That code still has problems, but I thought it best to stick closely to fixing only the immediate problem.
The easiest way to display a BufferedImage is to show it in a JLabel via an ImageIcon.
My problem is I want to draw a huge Panel but its not possible to see this panel in a small size frame so i supposed to use ScrollPane and I used it..
But by scrolling clashes occurs so i cant see any panel there .i just want to fix it
Please anyone see my code and run it and help to solve the problem
import java.awt.*;
import javax.swing.*;
public class Swing{
JFrame frame;
Panel panel;
public static void main(String [] args){
Swing a = new Swing();
a.go();
}
public void go(){
frame = new JFrame();
panel = new Panel();
panel.setPreferredSize(new Dimension(5000, 5000));
JScrollPane scroll = new JScrollPane(panel);
frame.add(scroll);
frame.pack();
frame.setVisible(true);
}
class Panel extends JPanel{
public void paintComponent(Graphics g){
Graphics2D a = (Graphics2D)g;
a.setColor(Color.RED);
a.drawLine(50, 50, 5000, 5000);
}
}
}
Thanks in advance!
Always make sure to call super.paintComponent(g); to redraw the rest of the component. Otherwise these types of painting artifacts are seen.
import java.awt.*;
import javax.swing.*;
public class Swing{
JFrame frame;
Panel panel;
public static void main(String [] args){
Swing a = new Swing();
a.go();
}
public void go(){
frame = new JFrame();
panel = new Panel();
panel.setPreferredSize(new Dimension(5000, 5000));
JScrollPane scroll = new JScrollPane(panel);
frame.add(scroll);
frame.pack();
frame.setVisible(true);
}
class Panel extends JPanel{
public void paintComponent(Graphics g){
super.paintComponent(g); // VERY IMPORTANT!
Graphics2D a = (Graphics2D)g;
a.setColor(Color.RED);
a.drawLine(50, 50, 5000, 5000);
}
}
}
I'm trying to display a message in a JPanel.
I've used the drawString() function of the Graphics class.
Here's my code :
public class Frame {
JFrame frame;
JPanel panel;
Graphics graph;
Frame() {
frame = new JFrame();
panel = new JPanel();
frame.setTitle("My wonderful window");
frame.setSize(800, 600);
frame.ContentPane(panel);
frame.setVisible(true);
}
void displayMessage(String message) {
graph = new Graphics();
graph.drawString(message, 10, 20);
}
}
I've this error :
error: Graphics is abstract; cannot be instantiated
Override the JPanel's paintComponent(Graphics g) method. IN the method you have access to a valid Graphics instance. The method called on each paint.
But may be it's better to add a JLabel to the panel. The label initially has no text and when you have a message just call setText(messageText) of the label.
You should create subclasses for your JFrame and JPanel, and override the methods you want. You could try something like:
package test;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Frame extends JFrame {
public static final String message = "HELLO WORLD!!!";
public class Panel extends JPanel {
public void paintComponent(Graphics graph) {
graph.drawString(message, 10, 20);
}
}
public Frame() {
Panel panel = new Panel();
this.setTitle("My wonderful window");
this.setSize(800, 600);
this.setContentPane(panel);
this.setVisible(true);
}
public static void main(String[] args) {
new Frame();
}
}
Also, there are a lot of great books/tutorials about this. You should read one.
Edit:
You should also read about all the JComponents (JButtons, JLabels...). They're rather useful.
I tried to implement a simple GUI application,having a class extend JPanel and then adding it to a frame and adding a button,but nothing happens when I click on the button.What is wrong?
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class dup extends JPanel {
public void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.green);
g2d.fillRect(0, 0, this.WIDTH, this.HEIGHT);
System.out.println("inside paint component class");
}
}
public class drawing implements ActionListener {
JFrame frame;
dup d1;
public static void main(String args[]) {
drawing d2 = new drawing();
d2.go();
}
public void go() {
frame = new JFrame();
JButton button = new JButton("click me");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
d1 = new dup();
button.addActionListener(this);
frame.getContentPane().add(BorderLayout.WEST, button);
frame.getContentPane().add(BorderLayout.CENTER, d1);
frame.setSize(300, 300);
frame.setVisible(true);
}
public void actionPerformed(ActionEvent ae) {
frame.repaint();
}
}
What is wrong with this?
Width and height is wrong. It should be
g2d.fillRect(0, 0, this.getWidth(), this.getHeight());
You were using constants from ImageObserver class instead of width and height properties of the component.