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Why doesn't the image paint over my JPanel?

I have been struggling with this for some time. At first, I only used ActionListener, then I added the paintComponent, but I have no idea what to put there. I read some tutorials and used their code as an example, but it still doesn't work. Right now, the end result is the same as it was without PaintComponent.
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class Scream extends JPanel {
private JButton button = new JButton("OK");
private Color screenColor;
private JPanel panel = new JPanel();
private JFrame frame;
private Dimension screenSize;
private ImageIcon image;
private JLabel label = new JLabel(image);
private int x;
private int y;
private boolean mouseClicked;
public Scream() {
button.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e ) {
if (e.getSource() == button) {
mouseClicked = true;
frame.getContentPane().add(label);
frame.setSize(image.getIconWidth(), image.getIconHeight());
panel.repaint();
}
}
});
frame = new JFrame ("Existential angst");
screenColor = new Color(150, 100, 0);
panel.setBackground( screenColor );
frame.add(button, BorderLayout.PAGE_END);
frame.add(panel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(1300, 700);
frame.setVisible(true);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
image.paintComponent(this, g, 1300, 700);
}
public static void main (String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
Scream scream = new Scream();
}
});
}
}

If you are trying to dynamically add an image to a panel then you need to add the label to the panel. There is no need for any custom painting.
The basic code for adding components to a visible GUI is:
panel.add(...);
panel.revalidate();
panel.repaint();
Also, don't attempt to set the size of the frame to the size of the image. A frame contains a titlebar and borders. Instead you can use frame.pack();

I noticed a couple of issues:
image is never initialized to anything so it is null, effectively making the label empty. I assume maybe your example was just incomplete?
Once I initialized the image to something, your example still did not work. Turns out adding label without specifying any constraint basically does nothing (I assume since adding a component to a border layout without a constraint puts it in the center where panel already is). When I added the label to BorderLayout.NORTH, everything worked (though resizing the frame to the size of the image makes it only partially visible since the frame includes the OK button)

Using repaint() method properly

I have a button that when pressed calls a changecolor() method in a different class where some drawing is done. The button listener works fine and I see from some logging that the color was in fact changed but my drawing is not updated. This is my current implementation:
(This method is called when a button is clicked)
public void changeWarningLightColor(){
System.out.println("change color method called");
if(warningLights.equals(Color.GREEN)){
warningLights=Color.RED;
System.out.println(warningLights);
repaint();
}
else{
warningLights=Color.GREEN;
repaint();
}
}
and my drawing is created in the same file in the above method as follows:
#Override
protected void paintComponent(Graphics g){
super.paintComponent(g);
g.drawSomething();
//draw a bunch of lines
}
My question is what is the proper way to call repaint() in order to actually update the drawing? Do I need to somehow call g.repaint() or do something different?
Separate class where the frame is created:
public class MainWindow extends JFrame {
public MainWindow(){
JPanel Window = new JPanel();
JPanel LeftSidePanel = new JPanel();
LeftSidePanel.setLayout(new BorderLayout());
LeftSidePanel.add(new DrawStatus(),BorderLayout.CENTER); //where the drawing is added
Window.setLayout(new BoxLayout(Window,0));
Window.add(LeftSidePanel);
add(Window);
}
public static void main(String[] args) {
//main method for showing the frame we created with the panels, and circles inside it
MainWindow frame = new MainWindow();
frame.setSize((int) (.75*Toolkit.getDefaultToolkit().getScreenSize().getWidth()),(int) (.75*Toolkit.getDefaultToolkit().getScreenSize().getHeight()));
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
frame.setTitle("DVPWS v1.0");
frame.setResizable(false);
MenuBar menu = new MenuBar();
frame.setJMenuBar(menu);
frame.setVisible(true);
}
}

If you are using a Jframe (most likely are) do
yourFrame.repaint();
Optionally
yourPanel.repaint();

In this case you could do
public MainWindow mw = new MainWindow();
mw.repaint();
If that doesnt work(i had a similar problem) than your going to have to make an instance of JFrame instead of extending it.

Click button and get draw rectangle

I am new to Java....I studied that we can add two things on frame... I added button and in response by clicking on button I want rectangle as output....but i don't understand that..Why i am not getting output.....
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public class customizedgui5 implements ActionListener {
JButton button;
JFrame frame;
public static void main(String[] args) {
customizedgui5 hi = new customizedgui5();
hi.go();
}
public void go() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JButton button = new JButton("click me");
button.addActionListener(this);
myclass a = new myclass();
frame.getContentPane().add(button, BorderLayout.CENTER);
frame.getContentPane().add(a, BorderLayout.SOUTH);
frame.setSize(100, 100);
frame.setVisible(true);
}
public void actionPerformed(ActionEvent event) {
frame.repaint();
frame.revalidate();
}
}
class myclass extends JPanel {
public void paintComponent(Graphics g) {
g.setColor(Color.orange);
g.fillRect(20, 50, 100, 100);
}
}

I would start by taking a look at Performing Custom Painting.
The main problem in your code is you are getting NullPointerException when you click the button because the reference of frame is null.
It is null because you've shadowed it in the constructor (basically, declared another variable of the same name within the constructor)...
// I'm null..
JFrame frame;
public void go() {
// Not the same as frame above...
JFrame frame = new JFrame();
You are also going to not see any changes because of a number of reasons...
The myclass panel has no size. With BorderLayout, this won't be "too" much of a problem, but...
You've drawing outside of the visible range of the panel. The rectangle you are painting won't appear because it is being painted outside of the width and height of the panel.
The rectangle will appear before you press the button as paintComponent will be called to update the state of the panel once it's made visible on the screen...
The first thing you need to is provide some kind of size hints to the BorderLayout. Try adding...
#Override
public Dimension getPreferredSize() {
return new Dimension(120, 150);
}
To myclass.
You also don't need to repaint the frame, what you really want to repaint is the instance of myclass. Try updating customizedgui5 so that a becomes a instance variable (like frame...
//...
myclass a;
//...
public void go() {
//...
a = new myclass();
//...
}
public void actionPerformed(ActionEvent event) {
a.repaint();
}
Now, the rectangle will still be shown the moment that the panel is made visible on the screen. Sure you could try setting it invisible, but this will affect the layout of the frame, hiding your component to start with, so, instead, we need some kind of flag we can trip so we know when to paint the rectangle. This is easily achieved by using a simple boolean variable, for example...
class myclass extends JPanel {
private boolean paintRect;
public void setPaintRect(boolean paint) {
paintRect = paint;
repaint();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(120, 150);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
if (paintRect) {
g.setColor(Color.orange);
g.fillRect(20, 50, 100, 100);
}
}
}
Then in you actionPerformed method, you just need to set the flag...
public void actionPerformed(ActionEvent event) {
a.setPaintRect(true);
}
You may also want to take a read through Code Conventions for the Java Programming Language. It will make it easier for people to read your code...

When you click on your button, you're calling the method actionPerformed(ActionEvent event)
Take a look at what you did there. Currently, you repaint and re-validate the frame. If you want to add a rectangle to your frame, you need to do so by adding a new component to the frame that will draw the rectangle.
You could add another instance of your myclass JPanel which paints a rectangle like so:
public void actionPerformed(ActionEvent event) {
frame.getContentPane().add(new myclass(), BorderLayout.NORTH);
frame.repaint();
}
This would add your custom rectangle-drawing panel to the North section of your BorderLayout. If you want to add the rectangle "on top of" your button, you should embed your button within a JPanel, then add the rectangle-drawing panel to that instead of your main JFrame

Java Graphics repaint() on ButtonClick

I have this code and want to repaint my graphic when the Button gets pressed:
public class JDraw extends JFrame {
/**
* Draws a figur in a JFrame.
* The color of it is random and can get changed by a button.
*/
public static JButton okButton = new JButton("change color");
public JDraw(String newTitel) {
super.setTitle(newTitel);
}
//Main method
public static void main(String str[]) {
JDraw window = new JDraw("Graphic");
window.setSize(300, 450);
window.setVisible(true);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.add(okButton, BorderLayout.SOUTH);
okButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
//JDraw.repaint(); <-- problem
}
});
}
#Override
public void paint(final Graphics g) {
super.paint(g);
Random rand = new Random();
int r1 = rand.nextInt(255);
int b1 = rand.nextInt(255);
int g1 = rand.nextInt(255);
g.setColor(new Color(r1, g1, b1));
//head
g.drawOval(100, 50, 100, 100);
g.fillOval(100, 50, 100, 100); // filled
//more drawing stuff.....
}
}
However I have no idea how to do it, because I cant do the repaint in my ActionPerfomed.
Error: non-static method repaint() cannot be referenced from a static context
I hope somebody can help. :)

You need to make the following call in your actionPerformed:
window.repaint();
To be able to reference window from within you actionPerformed, you need to make your window variable final:
final JDraw window = ...;
However, if I can suggest a few improvements:
Don't extend JFrame
Don't override paint(Graphics) of JFrame
Instead create a class that extends JComponent or JPanel and set it as the content pane of the JFrame
Instead of overrding paint(Graphics), rather override paintComponent(Graphics)
Your okButton should not be static. Instead move all your code in a non-static method like initUI() and have a code like new JDraw().initUI();
Wrap the code starting your UI in a SwingUtilities.invokeLater(Runnable) so that your UI is properly initiated from the Event Dispatching Thread.

You can't refer to the class JDraw. You should use an object instead. The object in your case is window. So, use:
window.repaint();
It is like saying: Human, walk to the door. Human is the class. You can't tell Human to do something, you need an instance of Human, like Obama or Santa Claus. In your case: you can't tell JDraw to repaint, but the object of type JDraw, i.e.: window.

drawing on Jframe

I cannot get this oval to draw on the JFrame.
static JFrame frame = new JFrame("New Frame");
public static void main(String[] args) {
makeframe();
paint(10,10,30,30);
}
//make frame
public static void makeframe(){
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLabel emptyLabel = new JLabel("");
emptyLabel.setPreferredSize(new Dimension(375, 300));
frame.getContentPane().add(emptyLabel , BorderLayout.CENTER);
frame.pack();
frame.setVisible(true);
}
// draw oval
public static void paint(int x,int y,int XSIZE,int YSIZE) {
Graphics g = frame.getGraphics();
g.setColor(Color.red);
g.fillOval(x, y, XSIZE, YSIZE);
g.dispose();
}
The frame displays but nothing is drawn in it. What am I doing wrong here?

You have created a static method that does not override the paint method. Now others have already pointed out that you need to override paintComponent etc. But for a quick fix you need to do this:
public class MyFrame extends JFrame {
public MyFrame() {
super("My Frame");
// You can set the content pane of the frame to your custom class.
setContentPane(new DrawPane());
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(400, 400);
setVisible(true);
}
// Create a component that you can actually draw on.
class DrawPane extends JPanel {
public void paintComponent(Graphics g) {
g.fillRect(20, 20, 100, 200); // Draw on g here e.g.
}
}
public static void main(String args[]){
new MyFrame();
}
}
However, as someone else pointed out...drawing on a JFrame is very tricky. Better to draw on a JPanel.

Several items come to mind:
Never override paint(), do paintComponent() instead
Why are you drawing on a JFrame directly? Why not extends JComponent (or JPanel) and draw on that instead? it provides more flexibility
What's the purpose of that JLabel? If it sits on top of the JFrame and covers the entire thing then your painting will be hidden behind the label.
The painting code shouldn't rely on the x,y values passed in paint() to determine the drawing routine's start point. paint() is used to paint a section of the component. Draw the oval on the canvas where you want it.
Also, you're not seeing the JLabel because the paint() method is responsible for drawing the component itself as well as child components. Overriding paint() is evil =)

You are overriding the wrong paint() method, you should override the method named paintComponent like this:
#Override
public void paintComponent(Graphics g)

You need to Override an exist paint method that actually up to dates your Frame. In your case you just created your custom new method that is not called by Frame default.
So change your method to this:
public void paint(Graphics g){
}