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JFrame is empty when using JPanel

I have 2 Java classes, Game and BaseComponent.
I wanted to draw multiple components in my JFrame, but that doesn't work, since it will only display the last added component.
I think the solution is to add an JPanel, but that still doesn't quite work for me, since no object are being drawn, not even one.
Game:
public class Game
{
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setSize(300, 400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel jpanel = new JPanel();
JComponent component = new BaseComponent(0,0);
JComponent component2 = new BaseComponent(1,1);
jpanel.add(component);
jpanel.add(component2);
frame.add(jpanel);
frame.setVisible(true);
}
}
BaseComponent:
public class BaseComponent extends JComponent
{
private int x, y;
BaseComponent(int i, int y) {
this.x = i;
this.y = y;
}
#Override
public Dimension getPreferredSize() {
return new Dimension((x * 50) + 50, (y * 50) + 50);
}
#Override
protected void paintComponent(Graphics g)
{
drawBaseComponent(g, x, y);
}
void drawBaseComponent(Graphics g, int x, int y)
{
g.setColor(Color.GREEN);
g.fillRect(x*50, y*50, 50, 50);
}
}
As you can see, this code adds one component to the the panel, which is being added to the JFrame, but it's completely empty;
EDIT:
When using prefered size, the application draws two green boxes but the position is not right, I expected them in the place of the two red boxes.

JPanel uses a FlowLayout by default. This will attempt to size any components to the preferredSize, which is, by default 0x0, which is why, your component "appears" empty.
You will need to supply sizing hints, via getPreferredSize, in order to allow the layout management API to determine the best way to layout your component, for example
public class BaseComponent extends JComponent
{
private int x, y;
BaseComponent(int i, int i0) {
this.x = i;
this.y = i0;
}
#Override
public Dimension getPreferredSize() {
return new Dimension((x * 50) + 50, (y * 50) + 50);
}
#Override
protected void paintComponent(Graphics g)
{
drawBaseComponent(g, x, y);
}
void drawBaseComponent(Graphics g, int xLeft, int yTop)
{
g.setColor(Color.GREEN);
g.fillRect(x*50, y*50, 50, 50);
}
}

draw ellipse relative to panel java

Basically I want to draw an ellipse which its size is relative to JPanel in Java.
for example: Ellipse2D e = new Ellipse2D.Double(0, 0, w, h)
Which w and h is the size of the panel. So by doing this, the ellipse will automatically resize when the panel is changing its size.
I have tried this but actually it doesn't work, I wrote this code for testing only.
public class Help extends JFrame{
public static void main(String [] agrs){
Help h = new Help();
h.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
h.init();
}
public void init(){
this.setLayout(new FlowLayout());
this.setSize(2000, 1000);
JPanel a = new JPanel();
a.setPreferredSize(new Dimension(1000, 500));
a.setBorder(BorderFactory.createLineBorder(Color.yellow, 3));
Help_Option k = new Help_Option(a.getPreferredSize().width/2, a.getPreferredSize().height/4);
k.setPreferredSize(new Dimension(1000, 400));
a.add(k);
this.add(a);
this.validate();
this.setVisible(true);
}
}
class Help_Option extends JComponent implements MouseMotionListener{
private static int x, y;
private Ellipse2D ellipse = new Ellipse2D.Double(0, 0, x, y);
private Color c = Color.MAGENTA;
public Help_Option(int x, int y){
Help_Option.x = x;
Help_Option.y = y;
this.addMouseMotionListener(this);
}
public void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.BLUE);
g2d.draw(ellipse);
g2d.setColor(c);
g2d.fill(ellipse);
g2d.setColor(Color.BLACK);
g2d.setFont(new Font("TimesRoman", Font.BOLD, 20));
g2d.drawString("Here I am", 250, 100);
}
public void setColor(Color c){
this.c = c;
}
#Override
public void mouseDragged(MouseEvent e) {
}
#Override
public void mouseMoved(MouseEvent e) {
if(ellipse.contains(e.getX(), e.getY())){
setColor(Color.GREEN);
repaint();
}else{
setColor(Color.MAGENTA);
repaint();
}
}
}

Thank you for your code snippet. In order to make it work, you need to initalize the ellipse in the Help_Option-Constructor otherwise it is draw at 0, 0 with the widht and height of 0 and 0.
...
private Ellipse2D ellipse = null; //also works w/o this assignment.
private Color c = Color.MAGENTA;
public Help_Option(int x, int y){
Help_Option.x = x;
Help_Option.y = y;
ellipse = new Ellipse2D.Double(0, 0, x, y);
this.addMouseMotionListener(this);
}
...
If I change the code accordingly, the ellipse stays at its size even though I resize the window.
Please give me a hint (screenshot) what you mean.

I want to draw an ellipse which its size is relative to JPanel in Java.
Then you need to create the Ellipse object in the paintComponent() method. You can use the getWidth() and getHeight() methods to get the current size of the panel.

How can I get this Paintcomponent to act as I intended?

I was given the assignment to make a simple paint program in java that utilizes a GUI and has basic I/O capabilities. That was all I was told to do by my professor. However, I've only made one GUI program before, so jumping straight into this paint program has been a headache. Now I'm nearly done, but the program isn't really behaving as I expected. When new objects are drawn on the Panel, they draw invisible white rectangles on the objects underneath them that erases those objects. I think this is the result of the repaint(xMin, yMin, xMax - xMin + 1, yMax - yMin + 1); method in DrawShapes, but can't think of a way to fix it.
On the other hand, the objects are also not saving properly. I can get it to export a jpg as I intended, however, it will only export the last image drawn and not everything on the paintComponent canvas.
Lastly, the clear method in DrawShapes is working in a very similar way. When the clear method is activated, it will clear everything but the last image drawn.
Is there anyone more familiar than me with these tools that can see a way to fix these? This is only the first program I've utilized draw on, and I/O.
Here is the class for the panel that the shapes are supposed to drawn on:
/**
* #author me
*/
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.event.*;
public class DrawShapes extends JPanel{
Point startPoint = null;
Point endPoint = null;
public int drawType = 1;
BufferedImage image;
Graphics2D g2d;
public DrawShapes(){
setBackground(Color.WHITE);
MyMouseListener m1 = new MyMouseListener();
addMouseListener(m1);
addMouseMotionListener(m1);
}//end constructor
//sets draw type, which is the decider of what is being drawn.
public void setType(int type){
if(type == 1)
{
drawType = 1;
}
else if(type == 2)
{
drawType = 2;
}
else if(type == 3)
{
drawType = 3;
}
}//end setType
public void paintComponent(Graphics g)
{
super.paintComponent(g);
if (image == null)
{
createEmptyImage();
}
g.drawImage(image, 0, 0, null);
if (startPoint != null && endPoint != null)
{
int x = Math.min(startPoint.x, endPoint.x);
int y = Math.min(startPoint.y, endPoint.y);
int width = Math.abs(startPoint.x - endPoint.x);
int height = Math.abs(startPoint.y - endPoint.y);
switch (drawType)
{
case 1:
g.drawRect(x, y, width, height);
break;
case 2:
g.drawOval(x, y, width, height);
break;
case 3:
g.drawLine(startPoint.x, startPoint.y, endPoint.x, endPoint.y);
break;
}
}
}//end paintComponent
public void save()
{
BufferedImage bi = new BufferedImage(this.getSize().width, this.getSize().height, BufferedImage.TYPE_INT_RGB);
Graphics g = bi.createGraphics();
this.paint(g);
g.dispose();
try{ImageIO.write(bi, "png",new File("test.png"));
}catch (Exception e){}
}
private void createEmptyImage()
{
image = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_ARGB);
g2d = (Graphics2D)image.getGraphics();
g2d.setColor(Color.BLACK);
g2d.drawString("Add a shape by clicking and dragging.", 40, 15);
}
public void addRect(int x, int y, int width, int height, Color color)
{
g2d.setColor( color );
g2d.drawRect(x, y, width, height);
repaint();
}
public void addOval(int x, int y, int width, int height, Color color)
{
g2d.setColor( color );
g2d.drawOval(x, y, width, height);
repaint();
}
public void addLine(int x1, int y1, int x2, int y2, Color color)
{
g2d.setColor(color);
g2d.drawLine(x1, y1, x2, y2);
repaint();
}
public void clear()
{
createEmptyImage();
repaint();
}
class MyMouseListener extends MouseInputAdapter
{
private int xMin;
private int xMax;
private int yMin;
private int yMax;
public void mousePressed(MouseEvent e)
{
startPoint = e.getPoint();
endPoint = startPoint;
xMin = startPoint.x;
xMax = startPoint.x;
yMin = startPoint.y;
yMax = startPoint.y;
}
public void mouseDragged(MouseEvent e)
{
//This is code I found that should make it so the only area affected by the dragging is repainted.
endPoint = e.getPoint();
xMin = Math.min(xMin, endPoint.x);
xMax = Math.max(xMax, endPoint.x);
yMin = Math.min(yMin, endPoint.y);
yMax = Math.max(yMax, endPoint.y);
repaint(xMin, yMin, xMax - xMin + 1, yMax - yMin + 1);
}
public void mouseRelease(MouseEvent e)
{
//This code paints the shapes on the Buffered Image created as a canvas
int x = Math.min(startPoint.x, endPoint.x);
int y = Math.min(startPoint.y, endPoint.y);
int width = Math.abs(startPoint.x - endPoint.x);
int height = Math.abs(startPoint.y - endPoint.y);
if (width != 0 || height != 0)
{
g2d.setColor( e.getComponent().getForeground() );
// g2d.drawRect(x, y, width, height);
switch (drawType)
{
case 1:
addRect(x, y, width, height, e.getComponent().getForeground());
break;
case 2:
addOval(x, y, width, height, e.getComponent().getForeground());
break;
case 3:
addLine(startPoint.x, startPoint.y, endPoint.x, endPoint.y, e.getComponent().getForeground());
break;
}//end switch statement.
}
startPoint = null;
// repaint();
}
}
}//end class
And here is the code for the UI:
/*#author Me*/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class MyDrawUI extends JFrame
{
private DrawShapes draw = new DrawShapes();
private JPanel ButtonPanel = new JPanel();
private JFrame window = new JFrame("Draw!");
//constructor
MyDrawUI(){
buildUI();
}
void buildUI()
{
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setLayout(new GridLayout(2,2));
window.add(draw);
window.add(ButtonPanel, BorderLayout.SOUTH);
ButtonPanel.setBackground(Color.LIGHT_GRAY);
draw.setBackground(Color.WHITE);
//define buttons
JButton rectangle = new JButton("Rectangle");
JButton oval = new JButton("Oval");
JButton line = new JButton("Line");
JButton exit = new JButton("Exit");
JButton save = new JButton("Save");
JButton clear = new JButton("Clear");
//add buttons
ButtonPanel.add(rectangle, BorderLayout.SOUTH);
ButtonPanel.add(oval, BorderLayout.SOUTH);
ButtonPanel.add(line, BorderLayout.SOUTH);
ButtonPanel.add(clear, BorderLayout.SOUTH);
ButtonPanel.add(save, BorderLayout.SOUTH);
ButtonPanel.add(exit, BorderLayout.SOUTH);
ButtonPanel.setSize(100, 100);
save.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
draw.save();
}
});
clear.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
draw.clear();
}
});
rectangle.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
draw.setType(1);
}
});
oval.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
draw.setType(2);
}
});
line.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
draw.setType(3);
}
});
exit.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
System.exit(0);
}
});
window.setVisible(true);
window.setSize(1024, 800);
}
}

There are a few issues I can see, the main one is the fact that you "think" you've overridden a method in the MouseAdaptor class, but haven't
mouseRelease is not method that will cause any events to trigger it. The method you're after is mouseReleased.
When overriding methods, make use the #Override annotation, it will cause a compiler error if the method you "think" you're overriding doesn't exist in any of the parent classes.
#Override
public void mouseReleased(MouseEvent e) {
Several other things pop out.
You're MyDrawUI classes extends from JFrame, but you create a instance of another JFrame called window, onto which you create your UI. In this case, drop the extends JFrame from the MyDrawUI class, as it just adds confusion...
Maintaining a reference to a Graphics context, even one you created, is ill advised in this context. On some systems, until you call dispose it's possible that nothing will be committed to the underlying implementation. Instead, simply use image.getGraphics when you need it and call g2d.dispose when you're done with it.

Click on icon in a JTextField and clear its content

I am trying to create a JTextField with an image and a hint. The function of the textfield is a search field to search some books. Now, I like to go a little bit further. I would like to give the image a function. For example, if I click on the image the text in the textfield should be cleared.
To achieve this implementation I created a new class and extended it with JTextField.
This is the code:
public class JSearchTextField extends JTextField implements FocusListener {
/**
*
*/
private static final long serialVersionUID = 1L;
private String textWhenNotFocused;
private Icon icon;
private Insets dummyInsets;
private JTextField dummy;
public JSearchTextField() {
super();
Border border = UIManager.getBorder("TextField.border");
dummy = new JTextField("Suchen...");
this.dummyInsets = border.getBorderInsets(dummy);
icon = new ImageIcon(JSearchTextField.class.getResource("/images/clearsearch.png"));
this.addFocusListener(this);
}
public JSearchTextField(String textWhenNotFocused) {
this();
this.textWhenNotFocused = textWhenNotFocused;
}
public void setIcon(ImageIcon newIcon){
this.icon = newIcon;
}
public String getTextWhenNotFocused() {
return this.textWhenNotFocused;
}
public void setTextWhenNotFocused(String newText) {
this.textWhenNotFocused = newText;
}
public void paintComponent(Graphics g){
super.paintComponent(g);
int textX = 2;
if(!this.hasFocus() && this.getText().equals("")) {
int height = this.getHeight();
Font prev = this.getFont();
Font italic = prev.deriveFont(Font.ITALIC);
Color prevColor = g.getColor();
g.setFont(italic);
g.setColor(UIManager.getColor("textInactiveText"));
int h = g.getFontMetrics().getHeight();
int textBottom = (height - h) / 2 + h - 4;
int x = this.getInsets().left;
Graphics2D g2d = (Graphics2D) g;
RenderingHints hints = g2d.getRenderingHints();
g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
g2d.drawString(textWhenNotFocused, x, textBottom);
g2d.setRenderingHints(hints);
g.setFont(prev);
g.setColor(prevColor);
} else {
int iconWidth = icon.getIconWidth();
int iconHeight = icon.getIconHeight();
int x = dummy.getWidth() + dummyInsets.right;
textX = x - 420;
int y = (this.getHeight() - iconHeight)/2;
icon.paintIcon(this, g, x, y);
}
setMargin(new Insets(2, textX, 2, 2));
}
#Override
public void focusGained(FocusEvent arg0) {
this.repaint();
}
#Override
public void focusLost(FocusEvent arg0) {
this.repaint();
}
}
And this is where I create the fields;
txtSearchBooks = new JSearchTextField("Buch suchen...");
Now back to my question. Do you have any idea how I can give the image a function where the text will be automatically cleared? I tried to implement a MouseListener and set the text of "txtSearchBooks" to null but it hasn't worked.
I hope I didn't go off in the wrong direction.
Sorry for the long post but I would really appreciate to get some advice.

A JTextField is a JComponent, meaning it is also a container for other components. You can use the add(Component c) method to add other components to it. BUT A JTextField won't show its added components unless you provide a LayoutManager to it. Then it behaves just like a normal JPanel.
I made a small example how you can manage what you need. The label is showed to the right, and clicking it will clear the field. You can use a button as well, instead of label.
Please note you don't need to create the Image object from scratch as I do, you can load it from a file. I create it this way so that the example doesn't rely on other files.
public class TextFieldWithLabel {
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JTextField textField = new JTextField("Search...");
textField.setLayout(new BorderLayout());
//creating dummy image...
Image image = new BufferedImage(25, 25, BufferedImage.TYPE_INT_RGB);
Graphics graphics = image.getGraphics();
graphics.setColor(Color.WHITE);
graphics.fillRect(0, 0, 25, 25);
graphics.setColor(Color.RED);
graphics.fillRect(2, 11, 21, 3);
graphics.fillRect(11, 2, 3, 21);
JLabel label = new JLabel(new ImageIcon(image));
textField.add(label, BorderLayout.EAST);
label.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
textField.setText("");
}
});
frame.add(textField);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}

How to "paint" on JLabels on a JPanel?

I have a set of JLabels, each containing a letter (via seText()), opaque and background set to white, on a JPanel with a GridLayout so the labels are forming a table.
I am doing a simple animation of highlighting certain rows and columns then there intersection. I can use the setBackground() of labels for this purpose, but thought I'd have more "choices" if a was able to use a Graphics object (maybe drawing a circle around intersection, then clearing it).
I tried to extend JLabel, or drawing on the JPanel directly(using getGraphics() in a method) but it didn't work, I think the drawing is behind the labels in this case. I can't figure out where should the "painting" code be placed in either case, nothing appeared on the screen.
in short, a method like the following, can be used to draw on top of labels?
should it be a JLabel or a JPanel method?
public void drawsomething() {
Graphics2D g2d = (Graphics2D) getGraphics();
g2d.fillRect(100, 100, 100, 100);
}

What if you override paintChildren() ?
protected void paintChildren(Graphics g) {
super.paintChildren(g);
//paint your lines here
}

You might want to try a JLayeredPane to paint your specific drawings on top of the existing JComponents
see example here http://docs.oracle.com/javase/tutorial/uiswing/components/layeredpane.html

I really don't know much about drawing stuff yet, but just created one small sample code for you to look at, hopefully you can get some information out of it. In order to paint on the JLabel you can use it's paintComponent(Graphics g) method.
A Sample Code :
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class DrawingOnJLabel extends JFrame
{
private CustomLabel label;
private int flag = 1;
private JPanel contentPane;
public DrawingOnJLabel()
{
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
contentPane = new JPanel();
contentPane.setBackground(Color.WHITE);
label = new CustomLabel(200, 200);
label.setLabelText("A");
label.setValues(50, 50, 100, 100, 240, 60);
final JButton button = new JButton("CLEAR");
button.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
if (flag == 1)
{
label.setFlag(flag);
flag = 0;
button.setText("REPAINT");
contentPane.revalidate();
contentPane.repaint();
}
else if (flag == 0)
{
label.setFlag(flag);
flag = 1;
button.setText("CLEAR");
contentPane.revalidate();
contentPane.repaint();
}
}
});
}
});
contentPane.add(label);
add(contentPane, BorderLayout.CENTER);
add(button, BorderLayout.PAGE_END);
setSize(300, 300);
setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
new DrawingOnJLabel();
}
});
}
}
class CustomLabel extends JLabel
{
private int sizeX;
private int sizeY;
private int x, y, width, height, startAngle, arcAngle;
private int flag = 0;
private String text;
public CustomLabel(int sX, int sY)
{
sizeX = sX;
sizeY = sY;
}
// Simply call this or any set method to paint on JLabel.
public void setValues(int x, int y, int width, int height, int startAngle, int arcAngle)
{
this.x = x;
this.y = y;
this.width = width;
this.height = height;
this.startAngle = startAngle;
this.arcAngle = arcAngle;
repaint();
}
public void setFlag(int value)
{
flag = value;
repaint();
}
public Dimension getPreferredSize()
{
return (new Dimension(sizeX, sizeY));
}
public void setLabelText(String text)
{
super.setText(text);
this.text = text;
flag = 0;
repaint();
}
public void paintComponent(Graphics g)
{
if (flag == 0)
{
g.setColor(Color.RED);
g.drawString(text, 20, 20);
g.setColor(Color.BLUE);
g.drawOval(x, y, width, height);
g.fillOval(x + 20, y + 20, 15, 15);
g.fillOval(x + 65, y + 20, 15, 15);
g.fillRect(x + 40, y + 40, 5, 20);
g.drawArc(x + 20, y + 30, 55, 55, startAngle, arcAngle);
}
else if (flag == 1)
{
g.clearRect(x, y, width, height);
}
}
}

Use paintComponent(Graphics g) instead of paint(Graphics g). That will paint over the GUI