We Keep Coding

Simple paint program using JPanel shows random images of JButtons

I'm trying to make a simple paint program in Java. It has 3 colors and a JField to enter the thickness. It works, except every time I enter a button, an image of that button shows up in the JPanel that contains the drawing portion.
I know that I can set the paintPane JPanel to opaque, but it relies on drawing over it self for the painting to work - otherwise it just drags a point around the screen. Thanks!!!
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class SimplePainting
{
//The main method simply creates a frame, and terminates the program
//once that frame is closed.
public static void main (String [] args)
{
PaintFrame frame = new PaintFrame();
frame.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
}
);
}
}
class PaintFrame extends JFrame implements ActionListener
{
JPanel pane;
PaintPane drawPane;
Color paintColor = Color.black;
private int radius = 5;
//holds the thickness of the line
JTextField thick;
public PaintFrame ()
{
//We use the JFrame consturctor to add a title to the frame
super("Windows Paint");
//set the main content pane
pane = (JPanel)getContentPane();
pane.setLayout(new BorderLayout());
//make a pane to hold the drawing
drawPane = new PaintPane();
drawPane.addMouseMotionListener(drawPane);
//Make a JPanle to hold all of the buttons
JPanel buttonPane = new JPanel();
buttonPane.setLayout(new GridLayout(1,6));
//add the buttons
JButton black = new JButton("Black");
buttonPane.add(black);
JButton red = new JButton("Red");
buttonPane.add(red);
JButton green = new JButton("Green");
buttonPane.add(green);
//Make a field to re-enter the thickness
thick = new JTextField(3);
thick.setText("5");
JButton thickness = new JButton("Reset Thickness");
thickness.addActionListener(this);
buttonPane.add(thickness);
buttonPane.add(thick);
JButton reset = new JButton("New Drawing");
reset.addActionListener(this);
buttonPane.add(reset);
black.addActionListener(this);
red.addActionListener(this);
green.addActionListener(this);
pane.add(drawPane, BorderLayout.CENTER);
pane.add(buttonPane, BorderLayout.SOUTH);
setSize(500,200);
setVisible(true);
}
public void actionPerformed(ActionEvent e)
{
if (e.getActionCommand().equals("Black"))
paintColor = Color.black;
else if (e.getActionCommand().equals("Red"))
paintColor = Color.red;
else if (e.getActionCommand().equals("Green"))
paintColor = Color.green;
else if (e.getActionCommand().equals("Reset Thickness"))
{
if (thick.getText() != "")
{
int lineThickness = Integer.parseInt(thick.getText());
radius = lineThickness;
}
}
else if (e.getActionCommand().equals("New Drawing"))
{
drawPane.startPaint = false;
drawPane.repaint();
}
}
class PaintPane extends JPanel implements MouseMotionListener
{
private int x;
private int y;
// don't paint a point until mouse is dragged
boolean startPaint = false;
public PaintPane()
{
setBackground(Color.white);
}
//paints a circle centered at x,y
public void paint(Graphics g)
{
//recall that the frist (x,y) coordiantes represent the top left
//corner of a box holding the circle
g.setColor(paintColor);
if (startPaint)
g.fillOval(x-radius,y-radius, 2*radius, 2*radius);
else
super.paintComponent(g);
}
public void mouseDragged(MouseEvent e)
{
startPaint = true;
x = e.getX();
y = e.getY();
repaint();
}
public void mouseMoved(MouseEvent e)
{
}
}
}

Java GUI: Objects and Label are not visible

I've intended to create a simple gui that would draw an oval in the top third of the window, display a name in the middle third, and draw a rectangle in the bottom third(to be done later)
So far, the only parts I've been able to create and make visible are four buttons that are eventually meant to toggle the visibility of the objects and label.
The problem I'm having is that I cannot get the label or the oval to appear, and I'm not sure what I'm missing preventing either to be visble
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import java.io.*;
public class Gui extends JFrame
implements ActionListener
{
private JButton bottomLeftButton;
private JButton bottomMiddleLeftButton;
private JButton bottomRightButton;
private JButton bottomMiddleRightButton;
private OtherPanel mypanel;
private JLabel name;
private JPanel panelOne;
private boolean visible;
public void actionPerformed(ActionEvent e)
{
if(e.getSource() == bottomLeftButton)
{
visible = name.isVisible();
name.setVisible(visible);
}
else if(e.getSource() == bottomMiddleLeftButton)
{
}
else if (e.getSource() == bottomMiddleRightButton)
{
}
else if (e.getSource() == bottomRightButton)
{
}
repaint();
}
public Gui()
{
setTitle("First GUI");
setSize(800,800);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container contentPane = this.getContentPane();
contentPane.setLayout(new BorderLayout());
JPanel BottomPanel = new JPanel(new GridLayout(1,4));
contentPane.add(BottomPanel, BorderLayout.SOUTH);
bottomLeftButton = new JButton("Name");
bottomLeftButton.addActionListener(this);
BottomPanel.add(bottomLeftButton);
bottomMiddleLeftButton = new JButton("Oval");
bottomMiddleLeftButton.addActionListener(this);
BottomPanel.add(bottomMiddleLeftButton);
bottomMiddleRightButton = new JButton("Square");
bottomMiddleRightButton.addActionListener(this);
BottomPanel.add(bottomMiddleRightButton);
bottomRightButton = new JButton("Special");
bottomRightButton.addActionListener(this);
BottomPanel.add(bottomRightButton);
JPanel centerPanel = new JPanel();
centerPanel.setLayout(new GridLayout(3,1));
panelOne = new OtherPanel();
name = new JLabel("Name");
name.setHorizontalAlignment(SwingConstants.CENTER);
JLabel label3 = new JLabel("Label3");
centerPanel.add(panelOne);
centerPanel.add(name);
centerPanel.add(label3);
}
public static void main(String[] args)
{
Gui gui = new Gui();
gui.setVisible(true);
}
}
(meant to draw the oval)
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class OtherPanel extends JPanel
{
public void paintComponent(Graphics g)
{
int x = 10;
int y = 10;
int width = getWidth(); //ten pixels of spaces
int height = getHeight();
g.fillOval(x, y, width, height);
}
}

was missing a line of code to add the objects to the contentPane
contentPane.add(centerPanel); goes at the end of the gui() method

Transfer value to an external method in Java

So I have a program that's meant to update a thermometer bar (using drawRect) dynamically based on the position of a JSlider. What I'm trying to do is to pass that value to an external method so I can use it to update the size of the rectangle. I'm a VB guy so I'm having trouble figuring out how to do it.
Here's my main class:
import javax.swing.*;
import java.awt.*;
import javax.swing.event.*;
public class ThermoProject extends JApplet
{
JSlider mySlider;
JPanel sliderPanel;
JPanel northernPanel = new NorthPanel();
JLabel printLabel = new JLabel("");
static int fillSize = 0;
int topSize = 100;
public void init() //init is the "main" for an applet
{
buildSliderPanel();
sliderPanel.setBackground(Color.gray);
add(northernPanel, BorderLayout.NORTH); //separate class
add(printLabel, BorderLayout.WEST); //add label to top
add(sliderPanel, BorderLayout.SOUTH); //add the panel to the south of the borderLayout
}
private void buildSliderPanel()
{
sliderPanel = new JPanel();
//JSlider(direction, beginning, end, initial location)
mySlider = new JSlider(JSlider.HORIZONTAL, 0, 100, 0);
mySlider.setMajorTickSpacing(10);
mySlider.setPaintTicks(true);
mySlider.setPaintLabels(true);
mySlider.setSnapToTicks(true);
//add listener
mySlider.addChangeListener(new SliderListener());
//add to panel
sliderPanel.add(mySlider);
}
public class SliderListener implements ChangeListener
{
public void stateChanged(ChangeEvent e)
{
//change when slider is moved
updateThermo(mySlider.getValue());
//topSize = 100 - fillSize;
//drawRect(x, y, width, height)
//fillRect(x, y, width, height)
repaint();
}
}
}
And here's my subclass, which is mostly used to build a separate JPanel.
import javax.swing.*;
import java.awt.*;
import javax.swing.event.*;
public class NorthPanel extends JPanel
{
JPanel theNorthernPanel;
int fillSize = 0;
public void paint(Graphics g)
{
//drawRect() and fillRect() args are x, y, width, height
g.drawRect(90, 90, 200, 30);
g.setColor(Color.red);
g.fillRect(90, 90, fillSize, 30);
}
public NorthPanel()
{
JPanel theNorthernPanel = new JPanel();
setPreferredSize(new Dimension(200, 200));
JLabel printLabel = new JLabel(String.valueOf(fillSize));
theNorthernPanel.add(printLabel);
add(theNorthernPanel);
}
public void updateThermo(int temperature)
{
fillSize = temperature;
}
}

try this:
NorthPanel northernPanel = new NorthPanel(); // to declare
and then,
northernPanel.updateThermo(mySlider.getValue()); //to call

You paint code is broken, start by taking a look at Painting in AWT and Swing and Performing Custom Painting for more details.
To call a method, you need a reference to the instance of the class you want to call...
Start by changing
JPanel northernPanel = new NorthPanel();
to
NorthPanel northernPanel = new NorthPanel();
And then use it to call the method....
northernPanel.updateThermo(mySlider.getValue());

I belive that you should change the content of the SliderListener to:
public class SliderListener implements ChangeListener
{
public void stateChanged(ChangeEvent e)
{
//change when slider is moved
((NorthPanel)northernPanel).updateThermo(mySlider.getValue());
//topSize = 100 - fillSize;
//drawRect(x, y, width, height)
//fillRect(x, y, width, height)
northernPanel.repaint();
}
}
In the code snippet you presented you're trying to invoke a member of ThermoProject.
Also take notion of casting to NorthPanel which is necessary, because you declared northernPanel as a more general type:
JPanel northernPanel = new NorthPanel();

Random circles JAVA

I am trying to create a GUI that will take in the number of circles to draw, and draw them in drawPanel with random locations/sizes. On my actionListener, when I try to draw the circle, it gives me red lines on my drawOval
1st class:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JTextArea;
/**
*
* #author Chris
*
*/
public class CirclesPanel extends JPanel{
private JButton draw, clear;
private JTextArea textArea;
private JPanel panel, drawPanel, buttonPanel;
private int count;
/**constructor
* builds the frame
*/
public CirclesPanel(){
//creates buttons and textArea
draw = new JButton("Draw");
clear = new JButton("Clear");
textArea = new JTextArea(1,10);
textArea.setBorder(BorderFactory.createTitledBorder("Circles"));
//creats panel
JPanel panel = new JPanel();
panel.setLayout(new BorderLayout());
setPreferredSize(new Dimension(620, 425));
//creates subpanel drawPanel
JPanel drawPanel = new JPanel();
drawPanel.setPreferredSize(new Dimension(450,400));
drawPanel.setBackground(Color.BLACK);
//creates subpanel buttonPanel
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new GridLayout(3,1));
//adds all the content to the frame
add(panel);
add(buttonPanel, BorderLayout.WEST);
add(drawPanel, BorderLayout.EAST);
buttonPanel.add(textArea);
buttonPanel.add(draw);
buttonPanel.add(clear);
//reads if the draw button is clicked
draw.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
count =Integer.parseInt(textArea.getText());//takes the count in
repaint();//repaints the picture to add the circles
}
});
//reads if the clear button is clicked
clear.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
count=0;//sets the count to 0 so nothing is painted
repaint();//repaints the window
}
});
}
/**Paint component
* draws the random circles
*/
public void paintComponent(Graphics g) {
Random generator = new Random();
int x, y, diameter;
for(int i = 0; i < count; i++){ //loop that takes the count and does this "x" times
g.setColor(Color.BLUE);//sets color to blue
x = generator.nextInt(90);//random location for x
y = generator.nextInt(90);//random location for y
diameter = generator.nextInt(30);//random size
g.fillOval(x, y, diameter, diameter);//draws the circle
}
}
}
2nd class
import javax.swing.JFrame;
public class Circles {
public static void main(String[]args){
JFrame frame = new JFrame("Cicles HW9");
frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new CirclesPanel());
frame.pack();
frame.setVisible(true);
}
}

So in your, I did little addition, first of all, I made the whole program in one class(CIRLCES PANEL), IF You want to use the second class, you can use it....
Problem is coming, your program is not the reading the ActionPerformed method for the drawing, means it is not located with the button, now I directly added it with your button(DRAW), now whenever you click on the button, it automatically reads the your textArea value, and draw your circles. I made your text area FINAL, So you can use it anywhere......
Now things that you need to do----
- this program is drawing circle on the whole frame, means not on your drawing Panel, you need to set the values, so it will draw on your draw panel area
- Also you need to add color for your oval, because it will either draw black color circle, which you will not able to see.....
and also one thing I forget to mentioned you, is that your, you also need to add code for your clear method...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JTextArea;
public class CirclesPanel extends JPanel{
private JButton draw, clear;
private JTextArea textArea;
private JPanel panel, drawPanel, buttonPanel;
private int count;
public CirclesPanel(){
JButton draw = new JButton("Draw");
JButton clear = new JButton("Clear");
final JTextArea textArea = new JTextArea(1,10);
textArea.setBorder(BorderFactory.createTitledBorder("Circles"));
JPanel panel = new JPanel();
panel.setLayout(new BorderLayout());
setPreferredSize(new Dimension(620, 425));
JPanel drawPanel = new JPanel();
drawPanel.setPreferredSize(new Dimension(450,400));
drawPanel.setBackground(Color.BLACK);
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new GridLayout(3,1));
add(panel);
add(buttonPanel, BorderLayout.WEST);
add(drawPanel, BorderLayout.EAST);
buttonPanel.add(textArea);
buttonPanel.add(draw);
buttonPanel.add(clear);
draw.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
count =Integer.parseInt(textArea.getText());
repaint();
}
});
}
public void paintComponent(Graphics g) {
Random generator = new Random();
int x, y, diameter;
for(int i = 0; i < count; i++){
x = generator.nextInt(90);
y = generator.nextInt(90);
diameter = generator.nextInt(30);
g.drawOval(x, y, diameter, diameter);
}
}
}

What you want to do is drawing some random circles on the drawPanel when button clicked. I write you a simplified version to show how things work.
I only keep the drawButton and paintPanel to keep things simple.
public class PaintFrame extends JFrame {
private JPanel content = new JPanel();
private JButton drawButton = new JButton("Draw");
private PaintPanel paintPanel = new PaintPanel();
public PaintFrame() {
getContentPane().add(content);
content.setLayout(new BorderLayout());
drawButton.setSize(100, 500);
drawButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
// drawButton is fired, repaint the paintPanel
paintPanel.repaint();
}
});
content.add(drawButton, BorderLayout.WEST);
content.add(paintPanel, BorderLayout.CENTER);
}
}
You need a new class extending the JPanel and override the paintComponent method to do the paint job for you. This makes sure you are drawing on the panel.
class PaintPanel extends JPanel {
public PaintPanel() {
setSize(500, 500);
setBackground(Color.BLACK);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Random random = new Random();
g.setColor(Color.WHITE);
// draw 5 random circles
int count = 5;
for (int i = 0; i < count; i++) {
g.drawOval(random.nextInt(250), random.nextInt(250),
random.nextInt(250), random.nextInt(250));
}
}
}
Main class
public class DrawMain {
public static void main(String[] args) {
JFrame frame = new PaintFrame();
frame.setDefaultCloseOperation(PaintFrame.EXIT_ON_CLOSE);
frame.setSize(600, 500);
frame.setVisible(true);
}
}

Drawing multiple shapes depending on user Java Swing

I am trying to implement a menu based graph - wherein i will represent a vertex by a circle and each circle will have an index provided by the user.The user has to go to File menu and click on Addvertex to create a new node with an index.The Problem though is - The circle is drawn only once - any subsequent clicks to addVertex does not result in drawing of a circle -Can't understand Why...
Here is my code:
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.io.*;
import java.util.*;
public class FileChoose extends JFrame {
public FileChoose() {
JMenuBar l=new JMenuBar();
JMenu file=new JMenu("File");
JMenuItem open=new JMenuItem("Addvertex");
open.addActionListener(new Drawer());
JMenuItem close=new JMenuItem("Exit");
close.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
});
JMenu tools=new JMenu("Tools");
file.add(open);
file.add(close);
this.setJMenuBar(l);
l.add(tools);
l.add(file);
this.setSize(new Dimension(200, 200));
this.setLocationRelativeTo(null);
this.setDefaultCloseOperation(this.EXIT_ON_CLOSE);
}
void HelloHere(String p) {
Draw d = new Draw(p);
this.add(d);
setExtendedState(MAXIMIZED_BOTH);
}
class Drawer extends JFrame implements ActionListener {
Integer index;
public void actionPerformed(ActionEvent e) {
JPanel pn = new JPanel();
JTextField jt = new JTextField(5);
JTextField jt1 = new JTextField(5);
pn.add(jt);
pn.add(jt1);
int result=JOptionPane.showConfirmDialog(null, pn, "Enter the values", JOptionPane.OK_CANCEL_OPTION);
if (result == JOptionPane.OK_OPTION) {
index = Integer.parseInt(jt.getText());
System.out.println(jt1.getText());
}
this.setVisible(true);
this.setSize(500, 500);
this.setLocationRelativeTo(null);
HelloHere(index.toString());
}
}
public static void main(String [] args) {
FileChoose f = new FileChoose();
f.setVisible(true);
}
}
class Draw extends JPanel {
String inp;
public Draw(String gn) {
inp = gn;
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
Random r = new Random();
int x = r.nextInt(100);
g2.drawOval(x, x * 2, 100, 100);
g2.drawString(inp, x + (x / 2), x + (x / 2));
}
}

Some pointers:
Use EDT for creation and manipulation of Swing Components.
Dont extend JFrame class unnecessarily.
Use anonymous Listeners where possible/allowed
Make sure JFrame#setVisible(..) is the last call on JFrame instance specifically pointing here:
this.setVisible(true);
this.setSize(500, 500);
this.setLocationRelativeTo(null);
HelloHere(index.toString());
Call pack() on JFrame instance rather than setSize(..)
Do not use multiple JFrames see: The Use of Multiple JFrames: Good or Bad Practice?
The problem you are having is here:
Draw d = new Draw(p);
this.add(d);
You are creating a new instance of Draw JPanel each time and then overwriting the last JPanel added with the new one (this is default the behavior of BorderLayout). To solve this read below 2 points:
Call revalidate() and repaint() on instance after adding components to show newly added components.
Use an appropriate LayoutManager
As I am not sure of you expected results I have done as much fixing of the code as I could hope it helps:
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.*;
import javax.swing.*;
public class FileChoose {
JFrame frame;
public FileChoose() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JMenuBar l = new JMenuBar();
JMenu file = new JMenu("File");
JMenuItem open = new JMenuItem("Addvertex");
open.addActionListener(new ActionListener() {
Integer index;
#Override
public void actionPerformed(ActionEvent e) {
JPanel pn = new JPanel();
JTextField jt = new JTextField(5);
JTextField jt1 = new JTextField(5);
pn.add(jt);
pn.add(jt1);
int result = JOptionPane.showConfirmDialog(null, pn, "Enter the values", JOptionPane.OK_CANCEL_OPTION);
if (result == JOptionPane.OK_OPTION) {
index = Integer.parseInt(jt.getText());
System.out.println(jt1.getText());
}
HelloHere(index.toString());
}
});
JMenuItem close = new JMenuItem("Exit");
close.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
});
JMenu tools = new JMenu("Tools");
file.add(open);
file.add(close);
frame.setJMenuBar(l);
l.add(tools);
l.add(file);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
void HelloHere(String p) {
Draw d = new Draw(p);
frame.add(d);
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.revalidate();
frame.repaint();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
FileChoose f = new FileChoose();
}
});
}
}
class Draw extends JPanel {
String inp;
public Draw(String gn) {
inp = gn;
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
Random r = new Random();
int x = r.nextInt(100);
g2.drawOval(x, x * 2, 100, 100);
g2.drawString(inp, x + (x / 2), x + (x / 2));
}
}
UPDATE:
Declare this globally in your Draw class: Random r=new Random(); as if you iniate a new Random instance each time you call paintComponent() the distributions will not be significant/random enough

Every time the user creates a new node you create a new JPanel that is added to the JFrame of your application. In the absence of a specific layout it uses a BorderLayout. BorderLayout does not allow for more than one component to be added at each location. Your other calls to add are probably ignored.