import java.awt.FlowLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JOptionPane;
public class Guiii extends JFrame{
private JButton menu;
private JButton custom;
public Guiii(){
super ("The Title");
setLayout(new FlowLayout());
menu = new JButton("menu Button");
add (menu);
Icon b = new ImageIcon (getClass().getResource("button.png"));
Icon x = new ImageIcon (getClass().getResource("greenbutton.png"));
custom = new JButton("Custom",b);
custom.setRolloverIcon(x);
add (custom);
HandlerClass handler = new HandlerClass();
menu.addActionListener(handler);
custom.addActionListener(handler);
}
private class HandlerClass implements ActionListener{
public void actionPerformed(ActionEvent event){
JOptionPane.showMessageDialog(null, String.format("~s", event.getActionCommand()));
}
}
}
This is my code I am having some trouble and its not working, I have made a main for it but errors are showing can anyone help me and explain how the code will work khg
These are the errors
Exception in thread "main" java.lang.NullPointerException
at javax.swing.ImageIcon.<init>(ImageIcon.java:205)
at Guiii.<init>(Guiii.java:22)
at main.main(main.java:7)
This is the rest of the code but it had to be in another file:
import javax.swing.JFrame;
public class main {
public static void main(String[] args) {
// TODO Auto-generated method stub
Guiii o = new Guiii();
o.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
o.setSize(300,200);
o.setVisible(true);
}
}
The constructor of the icon throws a NPE because getResource returns null.
Place the images in the same folder as the class Guiii.
Related
Ok so I will try to make this as understandable as possible. I have created a simple GUI with an "open" button and a textArea (along with other stuff but that's not important right now). Basically I am creating a method that when I click the Open button it displays the contents of the file in the textArea. I believe 99% of the method I have written is correct but I keep getting a NullPointerException and I don't quite understand why. Hopefully my code will clear up any confusion on what I am asking, I will comment on the line of code where I get the exception. Here is my code:
Application class (Basic setup of my GUI):
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
public class Application extends JFrame {
public OutputPanel outPanel = new OutputPanel();
public BarcodePanel barPanel = new BarcodePanel();
public ButtonPanel btnPanel = new ButtonPanel();
public ReferencePanel refPanel = new ReferencePanel();
public Application() {
super("Book Processor");
this.setLayout(new BorderLayout());
btnPanel.setLayout(new FlowLayout(FlowLayout.LEFT));
outPanel.setLayout(new FlowLayout(FlowLayout.LEFT));
refPanel.setLayout(new FlowLayout(FlowLayout.LEFT));
add(btnPanel, BorderLayout.NORTH);
add(outPanel, BorderLayout.WEST);
add(refPanel,BorderLayout.SOUTH);
}//end constructor
public static void main(String[] args) {
Application frame = new Application();
frame.setSize(1000,500);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}//end main
}//end class
The next set of code is my ButtonPanel class(this is where I am having an issue) So I have an openFile method, that when I click the button it should display the contents of the file in the textArea. Again I receive a NullPointerException and I do not understand why. Here is the code for this class:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.Closeable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Scanner;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
public class ButtonPanel extends JPanel{
JButton btnOpen = new JButton("Open");
OutputPanel outPanel = new OutputPanel();
Scanner input;
public ButtonPanel() {
ButtonHandler handler = new ButtonHandler();
add(btnOpen);
btnOpen.addActionListener(handler);
}//end constructor
/**
* Method for displaying the file onto the textArea.
*
*/
private void openFile() {
JFileChooser chooser = new JFileChooser();
chooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
int result = chooser.showOpenDialog(this);
String fileName;
fileName = chooser.getSelectedFile().getAbsolutePath();
try {
Scanner input = new Scanner(Paths.get(fileName));
StringBuilder sb = new StringBuilder();
while(input.hasNextLine()) {
sb.append(input.nextLine()+ "\n");
}
outPanel.txtOutput.setText(sb.toString());//my issue is with this line right here
} catch (IOException e) {
e.printStackTrace();
}
finally {
input.close();
}
}//end readFile
private class ButtonHandler implements ActionListener{
public void actionPerformed(ActionEvent e) {
if(e.getSource()== btnOpen) {
openFile();
}
}//end actionPerformed
}//end actionlistener
}//end class
Here is my last class, OutputPanel, this class contains the JTextArea:
import java.awt.BorderLayout;
import javax.swing.JPanel;
import javax.swing.JTextArea;
public class OutputPanel extends JPanel{
public JTextArea txtOutput = new JTextArea(20,50);
public OutputPanel() {
add(txtOutput);
}//end constructor
}//end class
How do I get the textArea to display the contents of the file. More importantly why am I getting this exception and what can I do to fix it. Hopefully this makes as much sense as possible, and I really appreciate any and all input from you guys.
I was creating a program to work with a drop-down list, but I got stuck at the line of declaration of JComboBox box, I get these error messages:
Multiple markers at this line
- The constructor JComboBox(String[]) is
undefined
- Line breakpoint:JComboBox [line: 25] -
JComboBox()
No matter how I try to define JComboBox, I get some sort of error. Please help me with it.
Here's the code of the public class:
import javax.swing.*;
import java.awt.FlowLayout;
import java.awt.Font;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JRadioButton;
import javax.swing.ButtonGroup;
import java.awt.event.ItemListener;
import java.awt.event.ItemEvent;
public class JComboBox extends JFrame {
private JComboBox box;
private JLabel picture;
private static String[] filename = { "p.png", "i.png" };
private Icon pics[] = { new ImageIcon(getClass().getResource(filename[0])),
new ImageIcon(getClass().getResource(filename[1])) };
public JComboBox() {
super("This is the title");
setLayout(new FlowLayout());
JComboBox box = new JComboBox(filename);
box.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent event) {
if (event.getStateChange() == ItemEvent.SELECTED) {
picture.setIcon(pics[box.getSelectedIndex()]);
}
}
});
add(box);
picture = new JLabel(pics[0]);
add(picture);
}
}
And here's the code of the main class:
import javax.swing.*;
public class JComboBox1 extends JFrame {
public static void main(String[] args) {
JComboBox Box = new JComboBox();
Box.setVisible(true);
Box.setSize(400,400);
Box.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
Thank you.
Your problem, as #Andy mentioned is that you have a collision in the name of your class and the swing component. If you absolutely must name your class JComboBox you'll have to reference the swing component by the fully-qualified name, as such
public class JComboBox extends JFrame {
private javax.swing.JComboBox box;
If you hover over your private instance with an IDE you should see the fully-qualified name matching the package in which you've created your JComboBox class. Save yourself some pain and rename your class.
I'd like to create a Java Swing Photo Album but I can't manage to find the right way to do it. I think it should be to create two ArrayList, one to stock the photo objects and another one to stock the buttons.
After that I should find a way to assign each images to the buttons and add them into the panel.
My question is : Do you think it is the right way to do it and if so, could you give me a hint? (For the last class at the bottom)
Here's my code at the moment :
Main :
import javax.swing.JFrame;
public class Main extends JFrame {
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
new AlbumFrame();
}
});
}
}
AlbumFrame :
import java.awt.BorderLayout;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class AlbumFrame extends JFrame {
private JPanel MenuPanel;
private JPanel PhotoPanel;
public AlbumFrame(){
super("JPhone");
setLayout(new BorderLayout());
PhotoPanel = new PhotoPanel();
add(PhotoPanel,BorderLayout.CENTER);
MenuPanel = new MenuPanel();
add(MenuPanel,BorderLayout.SOUTH);
setSize(480,800);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
}
}
MenuPanel
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JPanel;
import javax.swing.filechooser.FileNameExtensionFilter;
public class MenuPanel extends JPanel implements ActionListener{
private static final long serialVersionUID = 1L;
private JButton backButton;
private JButton homeButton;
private JButton turnButton;
private JButton addButton;
final private JFileChooser fc;
public MenuPanel(){
fc = new JFileChooser();
backButton = new JButton(new ImageIcon(getClass().getResource("/Images/back.png")));
homeButton = new JButton(new ImageIcon(getClass().getResource("/Images/home.png")));
turnButton = new JButton(new ImageIcon(getClass().getResource("/Images/turn.png")));
addButton = new JButton(new ImageIcon(getClass().getResource("/Images/add.png")));
backButton.setPreferredSize(new Dimension(55,55));
homeButton.setPreferredSize(new Dimension(55,55));
turnButton.setPreferredSize(new Dimension(55,55));
addButton.setPreferredSize(new Dimension(55,55));
backButton.addActionListener(this);
homeButton.addActionListener(this);
turnButton.addActionListener(this);
addButton.addActionListener(this);
setLayout(new FlowLayout(FlowLayout.CENTER));
add(backButton);
add(homeButton);
add(turnButton);
add(addButton);
}
public void actionPerformed(ActionEvent e) {
JButton clicked = (JButton)e.getSource();
//Test for the moment
if(clicked == backButton){
System.out.println("back");
}else if(clicked == homeButton){
System.out.println("home");
}else if(clicked == turnButton){
System.out.println("turn");
}else if(clicked == addButton){
int returnVal = fc.showOpenDialog(MenuPanel.this);
if(returnVal == JFileChooser.APPROVE_OPTION){
File file = fc.getSelectedFile();
}
}
}
}
PhotoPanel
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JPanel;
public class PhotoPanel extends JPanel implements ActionListener {
ArrayList<Photo> Album = new ArrayList<Photo>();
ArrayList<JButton> Buttons = new ArrayList<JButton>();
public PhotoPanel(){
setLayout(new FlowLayout(FlowLayout.CENTER));
}
public void actionPerformed(ActionEvent e) {
}
}
I would use separate class like PhotoCard to avoid lists:
class PhotoCard {
public PhotoCard(Photo photo) {
add(photo);
// also add buttons, listeners, etc.
}
}
that holds necessary data and initializes listeners.
And then class can be added to to your PhotoPanel:
PhotoPanel.add(new PhotoCard(...));
I minimized my program to include only the problem and I tried to code exactly as I understood from many examples. When I used the ActionListener, I get problem solved. But I wonder why using ItemListener, checkbox does not operate correctly.
If I run my program without ItemListener, it works correctly. With this ItemListener, checkBox doesn't change state.
import java.awt.FlowLayout;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
public class omaJFrame extends JFrame{
private JCheckBox checkBox1;
public omaJFrame() {
super("Window Title");
TheHandler handler = new TheHandler();
setLayout(new FlowLayout());
checkBox1 = new JCheckBox("Checkbox 1");
add(checkBox1);
checkBox1.addItemListener(handler);
}
private class TheHandler implements ItemListener {
String output = "";
public void itemStateChanged(ItemEvent event) {
if (event.getItem()==checkBox1)
output = String.format("%s", checkBox1.isSelected());
JOptionPane.showMessageDialog(null, output);
}
}
}
import javax.swing.JFrame;
public class EventHandlerMain {
public static void main(String[] args) {
omaJFrame window = new omaJFrame();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setSize(350,200);
window.setVisible(true);
}
}
Works for me. Note also that Swing GUI objects should be constructed and manipulated only on the event dispatch thread.
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
public class OmaJFrame extends JFrame {
private JCheckBox checkBox1;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
OmaJFrame f = new OmaJFrame();
}
});
}
public OmaJFrame() {
super("Window Title");
setDefaultCloseOperation(EXIT_ON_CLOSE);
TheHandler handler = new TheHandler();
setLayout(new FlowLayout());
checkBox1 = new JCheckBox("Checkbox 1");
add(checkBox1);
checkBox1.addItemListener(handler);
pack();
setLocationByPlatform(true);
setVisible(true);
}
private class TheHandler implements ItemListener {
String output = "";
#Override
public void itemStateChanged(ItemEvent event) {
if (event.getItem() == checkBox1) {
output = String.format("%s", checkBox1.isSelected());
}
JOptionPane.showMessageDialog(null, output);
}
}
}
Ok guys, I've made some changes in my code as told by you. I have 3 classes:
The second class (and first GUI): I have 4 JButtons - Simulare, CazParticular, Start and HandSelection, some JLabels and 3 JTextFields; When I press the HandSelection button another frame it's created with different content.
The 3rd class (and second GUI): I have 2 JButtons - Ok and Cancel and other stuff. When I press the Ok button I want to the access to the JTextField(QuesHandText) from the first Gui and use the method setText(). I can't figure this out, I'm thinking on this like 4-5 days and still can't get the answer. Please help me!
What code should I write in if statement to be able to modify the text in the JTextField from 2nd class (first GUI) ?
First class:
import javax.swing.JFrame;
public class Main {
public static void main(String[] args){
//other stuff
GuiMain gui = new GuiMain();
gui.frame1.setLocation(150,150);
gui.frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
gui.frame1.setSize(400,250);
gui.frame1.setResizable(false);
gui.frame1.setVisible(true);
//other stuff
}
}
Second class:
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.WindowEvent;
import javax.swing.*;
public class GuiMain {
public static GuiMain instance;
public static GuiMain getInstance(){
if(GuiMain.instance == null){GuiMain.instance = new GuiMain();}
return GuiMain.instance;
}
public JFrame frame1 = new JFrame();
public JTextField QuesHandText, FlopTurnRiverText, RezultatText;
public JButton Simulare, CazParticular, Start, HandSelection;
public int w1,h1;
public JLabel someText;
static int u=0;
public int j=0;
public GuiMain(){
frame1.setTitle("HoldemTool");
frame1.setLayout(null);
QuesHandText = new JTextField(4);
Simulare = new JButton("Simulare");
CazParticular = new JButton("Caz particular");
Start = new JButton("Start");
HandSelection = new JButton(new ImageIcon(getClass().getResource("GuiPic.png")));
Handler handler1 = new Handler();
CazParticular.addActionListener(handler1);
Simulare.addActionListener(handler1);
HandSelection.addActionListener(handler1);
Start.addActionListener(handler1);
QuesHandText.setEditable(false);
FlopTurnRiverText.setEditable(false);
RezultatText.setEditable(false);
frame1.add(Welcome1);
frame1.add(Welcome2);
frame1.add(QuesHand);
frame1.add(FlopTurnRiver);
frame1.add(Rezultat);
frame1.add(QuesHandText);
frame1.add(FlopTurnRiverText);
frame1.add(RezultatText);
frame1.add(Simulare);
frame1.add(CazParticular);
frame1.add(Start);
}
public JTextField getQuesHandText(){
return QuesHandText;
}
public class Handler implements ActionListener{
public void actionPerformed(ActionEvent e){
if(e.getSource()==Simulare)
{
}
if(e.getSource()==CazParticular){
QuesHandText.setEditable(true);
FlopTurnRiverText.setEditable(true);
QuesHandText.setText("");
FlopTurnRiverText.setText("");
RezultatText.setText("");
frame1.setSize(470, 250);
Start.setBounds(3*FlopTurnRiverText.getX(), QuesHand.getY(), 65, h1);
HandSelection.setBounds(3*FlopTurnRiverText.getX(), FlopTurnRiverText.getY(), 65, h1);
frame1.add(HandSelection);
frame1.add(Start);
}
if(e.getSource()==Start){
QuesHandText.setText("Text");
}
if(e.getSource()==HandSelection){
GuiSelection gui2 = new GuiSelection();
gui2.frame2.setVisible(true);
}
}
}}
3rd class
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.WindowEvent;
import javax.swing.*;
public class GuiSelection extends GuiMain {
JFrame frame2 = new JFrame();
GuiMain guiMain;
public JButton Ok,Cancel;
//other stuff
public GuiSelection(){
guiMain = new GuiMain();
frame2.setTitle("Hand selection");
frame2.setSize(1135,535);
frame2.setLayout(null);
frame2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame2.setVisible(true);
frame2.setResizable(false);
//other stuff
Handler2 handler2 = new Handler2();
Ok.addActionListener(handler2);
Cancel.addActionListener(handler2);
frame2.add(Ok); frame2.add(Cancel);
}
public class Handler2 implements ActionListener{
public void actionPerformed(ActionEvent e){
if(e.getSource()==Cancel){
frame2.hide();
}
if(e.getSource()==Ok)
{
GuiMain.getInstance().getQuesHandText().setText("From Ok");
//When I prees this button "Ok" I want to get access to the JTextField(QuesHandText) in the GuiMain class, and .setText();
//somothing like QuesHandtText.setText("someText");
}
}
}
}
Add to your first GUI the method public JTextField getQuesHandText() and a static method public static JFrame getInstance() which returns the instance of the first GUI. Now you can call SecondClass.getInstance().getQuesHandText() from anywhere to get the JTextField instance. Note that with this method you can only have a single instance of SecondClass at any time.
Your getInstance() method will look as follows:
public class SecondClass extends JFrame {
private static SecondClass instance;
public static SecondClass getInstance() {
if(SecondClass.instance == null)
SecondClass.instance = new SecondClass();
return SecondClass.instance
}
}
Note that you shouldn't create an instance of SecondClass manually.
Use Composition,
1. Create the instance of the class which contains the JFrame, whose JTextField you need to access.
2. Then on that instance call the setter or getter method of the JTextField.
Edited:
Make Sure you have implemented Singleton principle on the Main class, else you will get
a new instance , which you dont want......
In Second class.
public class GuiMain{
Main m = new Main();
m.getText();
m.setText();
// Other stuffs
}
Perhaps you do not really need two Windows. What you need is a Dialog which can be achieved by the class JOptionPane.
Here is a demo code.
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class YourGui implements ActionListener {
private JFrame frame;
private JTextField text;
private JButton takeInput;
public YourGui() {
frame = new JFrame();
frame.setLayout(new GridLayout(2, 1));
text = new JTextField();
takeInput = new JButton("Take Input!");
frame.add(text);
frame.add(takeInput);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400, 100);
takeInput.addActionListener(this);
}
public void show() {
frame.setVisible(true);
}
#Override
public void actionPerformed(ActionEvent e) {
int selection =
JOptionPane.showConfirmDialog(frame, "Select Hand", "Select",
JOptionPane.OK_CANCEL_OPTION);
if (selection == JOptionPane.OK_OPTION) {
text.setText("You selected ok");
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
YourGui gui = new YourGui();
gui.show();
}
});
}
}
Use the instance of the initiated Class to get access to its public variables. So you should do something like:
GuiMain main=new GuiMain();
...
main.QuesHandtText.setText("someText");
Alternatively if your JTextField is private (though its not) use an instance method that has public access to change its contents - this is the preferred method:
Class A:
class A {
private JTextField tf;
public void setFieldText(String text) {
tf.setText(text);
}
}
Class B:
class B {
A a = new A();
a.setText("hello");
}
In the handler of GuiMain, pass itself (the main JFrame) as an argument to the constructor of GuiSelection:
GuiSelection gui2 = new GuiSelection(this);
And then change the constructor of GuiSelection from
public GuiSelection(){
guiMain = new GuiMain();
...
to
public GuiSelection(GuiMain guiMain){
this.guiMain = guiMain;
...
Also, it seems quite odd that GuiSelection is a subclass of GuiMain. Probably both of these should be direct subclasses of JFrame.
Also, you should wrap everything in the main method within SwingUtilities.invokeLater since everything related to Swing should run on the event-dispatch thread.
Also, you should never use public member variables: it is very un-Java.