Im creating a programme using java. I want the user to enter some text, then push the button so the text entered shows in the label. However, I have 2 problems. First, the text are isn´t displaying when I execute the app. Second, I don´t know how to allow the user to type in the area. Im new in java so that´s why Im asking. Here is the code. Thank you.
import javax.swing.*;
import java.awt.event.*;
class Boton extends JFrame implements ActionListener {
JButton boton;
JTextArea textArea = new JTextArea();
JLabel etiqueta = new JLabel();
public Boton() {
setLayout(null);
boton = new JButton("Escribir");
boton.setBounds(100, 150, 100, 30);
boton.addActionListener(this);
add(boton);
}
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == boton) {
try {
String texto = textArea.getText();
etiqueta.setText(texto);
Thread.sleep(3000);
System.exit(0);
} catch (Exception excep) {
System.exit(0);
}
}
}
}
public class Main{
public static void main(String[] ar) {
Boton boton1 =new Boton();
boton1.setBounds(0,0,450,350);
boton1.setVisible(true);
boton1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
Problems:
You never add the JTextArea into your GUI, and if it doesn't show, a user cannot directly interact with it.
You are calling Thread.sleep on the Swing event thread, and this will put the entire application to sleep, meaning the text that you added will not show.
Other issues include use of null layouts and setBounds -- avoid doing this.
Solutions:
Set the JTextArea's column and row properties so that it sizes well.
Since your JTextArea's text is going into a JLabel, a component that only allows a single line of text, I wonder if you should be using a JTextArea at all. Perhaps a JTextField would work better since it allows user input but only one line of text.
Add the JTextArea to a JScrollPane (its viewport actually) and add that to your GUI. Then the user can interact directly with it. This is most easily done by passing the JTextArea into a JScrollPane's constructor.
Get rid of the Thread.sleep and instead, if you want to use a delay, use a Swing Timer. check out the tutorial here
For example:
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.Window;
import java.awt.event.KeyEvent;
import javax.swing.*;
public class Main2 {
public static void main(String[] args) {
// create GUI in a thread-safe manner
SwingUtilities.invokeLater(() -> createAndShowGui());
}
private static void createAndShowGui() {
BotonExample mainPanel = new BotonExample();
JFrame frame = new JFrame("GUI");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
}
class BotonExample extends JPanel {
private JLabel etiqueta = new JLabel(" ");
private JButton boton = new JButton("Escribir");
// jtext area rows and column properties
private int rows = 5;
private int columns = 30;
private JTextArea textArea = new JTextArea(rows, columns);
public BotonExample() {
// alt-e will activate button
boton.setMnemonic(KeyEvent.VK_E);
boton.addActionListener(e -> {
boton.setEnabled(false); // prevent button from re-activating
String text = textArea.getText();
etiqueta.setText(text);
// delay for timer
int delay = 3000;
Timer timer = new Timer(delay, e2 -> {
// get current window and dispose ofit
Window window = SwingUtilities.getWindowAncestor(boton);
window.dispose();
});
timer.setRepeats(false);
timer.start(); // start timer
});
// create JPanels to add to GUI
JPanel topPanel = new JPanel(new FlowLayout(FlowLayout.LEADING, 5, 5));
topPanel.add(new JLabel("Etiqueta:"));
topPanel.add(etiqueta);
JPanel bottomPanel = new JPanel();
bottomPanel.add(boton);
JScrollPane scrollPane = new JScrollPane(textArea);
// use layout manager and add components
setLayout(new BorderLayout());
add(topPanel, BorderLayout.PAGE_START);
add(scrollPane, BorderLayout.CENTER);
add(bottomPanel, BorderLayout.PAGE_END);
}
}
textarea.setText("Text"); // this will insert text into the text area
textarea.setVisable(true); // this will display the text area so you can type in it
textarea.setSize(500,500); // set size of the textarea so it actually shows
The user should be able to type in the TA when it is displayed and just do a getText to pull the text
Related
The commented codes are the problem. When I am using them, panels are added successfully, but I don't need these commented code anymore but same code is not working after I remove or comment those blocks.
Those codes that I have commented need to be removed. Without those commented codes, program runs but does not add panels. I use IntelliJ for my Java Project.
import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.awt.*;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
public class Test extends JFrame{
JPanel panel;
JButton send;
JTextField text;
JPanel chatArea;
boolean typing;
Test(){
setSize(365,515);
setLocation(50,100);
setLayout(null);
panel = new JPanel();
panel.setLayout(null);
panel.setBounds(0,0,350,60);
panel.setBackground(new Color(90000000));add(panel);
JLabel name = new JLabel("IRONMAN");
name.setFont(new Font("SAN_SERIF", Font.PLAIN,14));
name.setForeground(Color.white);
name.setBounds(110,35,120,20);panel.add(name);
text = new JTextField();
text.setBounds(15,430,260,40);
text.setFont(new Font("SAN_SERIF",Font.PLAIN,14));
text.setForeground(Color.BLUE);
// Timer timer = new Timer(1, event -> {
// if (!typing){
// name.setText("IRONMAN");
// }
// });
// timer.setInitialDelay(2000);
// text.addKeyListener(new KeyAdapter() {
// #Override
// public void keyPressed(KeyEvent e) {
// name.setText("IRONMAN typing...");
// timer.stop();
// typing = true;
// }
// #Override
// public void keyReleased(KeyEvent e) {
// typing = false;
// if (!timer.isRunning()){
// timer.start();
// }
// }
// });
add(text);
chatArea = new JPanel();
chatArea.setBounds(5,65,340,350);
add(chatArea);
send = new JButton("Send");
send.setBounds(280,430,65,30);
send.setBackground(new Color(200,120,255));
send.setForeground(new Color(7,95,75));
send.addActionListener(e -> {
String message = "STARK: "+text.getText();
JPanel p2 = formatLabel(message);
chatArea.add(p2);
text.setText("");
});
add(send);
}
private JPanel formatLabel(String message) {
JPanel p3 = new JPanel();
JLabel label1 = new JLabel("<html><p style = \"width : 150px\">" + message + "</p></html>");
label1.setBackground(new Color(200,120,255));
label1.setForeground(new Color(7,95,75));
label1.setFont(new Font("SAN_SERIF",Font.PLAIN,18));
label1.setOpaque(true);
label1.setBorder(new EmptyBorder(15,15,15,70));
p3.add(label1);
return p3;
}
public static void main(String[] args) {
Test t = new Test();
t.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
t.setVisible(true);
}
}
First off all some general comments:
label1.setBorder(new EmptyBorder(15,15,15,70));
Don't be afraid to use whitespace. For example
label1.setBorder(new EmptyBorder(15, 15, 15, 70));
It is easier for our eyes to see text with whitespace.
setLayout(null);
Don't use a null layout. Swing was designed to be used with layout managers. You can easily use the default BorderLayout of the JFrame. Add:
the top panel to BorderLayout.PAGE_START
the chat panel to BorderLayout.PAGE_CENTER
the bottom panel to BorderLayout.PAGE_END
after I remove or comment those blocks.
That code is not the solution or the problem.
The problem is that a component has a size of (0, 0) so there is nothing to paint.
In your existing code try resizing the frame by making it wider. The panel will appear. This is because the resizing will cause the layout manager to be invoked which will give the panel a size so it can be painted.
In your code you need to use:
chatArea.add(p2);
chatArea.revalidate();
The revalidate() will automatically invoke the layout manager.
I don't have a lot of experience with KeyListeners but I used one in my application and it works fine except I need to wait for input before my program can continue. For this I made a while loop that loops until the String temp is not null (which would mean there would be input).
The problem is there is no way to type in the JTextField (called input). Below is code from my two methods that are supposed to work together so that the text in my JTextField (input) can be returned (as temp). I'm not sure why this doesn't work or how to fix it.
The keyPressed method for my KeyListener:
public void keyPressed(KeyEvent e)
{
//only sends text if the enter key is pressed
if (e.getKeyCode()==KeyEvent.VK_ENTER)
{
//if there really is text
if (!input.getText().equals(""))
{
//String temp is changed from null to input
temp=input.getText();
//text sent to another JTextField
output.append(temp+"\n");
//input no longer has text
input.setText("");
}
}
}
The method thats trying to get text, also in my KeyListener class
public String getTemp()
{
booleans isNull=temp==null;
//loops until temp is not null
while (isNull)
{
//unnecessary line of code, only used so the loop not empty
isNull=checkTemp();
}
return temp;
}
public boolean checkTemp()
{
return temp==null;
}
Your while loop is a common console program construct, but understand that you're not creating a console program here but rather an event-driven GUI, and in this situation, the while loop fights against the Swing GUI library, and you need to get rid of it. Instead of a while loop with continual polling you now want to respond to events, and if you're listening for user input into a JTextField do not use a KeyListener as this low-level listener can cause unwanted side effects. Instead add a DocumentListener to the JTextField's Document.
Edit: You're listening for the enter key, and so the solution is even easier: add an ActionListener to the JTextField!
e.g.,
input.addActionListener(e -> {
String text = input.getText().trim();
if (text.isEmpty()) {
return;
}
output.append(text + "\n");
input.setText("");
});
More complete example:
import java.awt.BorderLayout;
import java.awt.event.ActionListener;
import javax.swing.*;
public class ChatBox extends JPanel {
private static final int COLS = 40;
private JTextField input = new JTextField(COLS);
private JTextArea output = new JTextArea(20, COLS);
private JButton submitButton = new JButton("Submit");
public ChatBox() {
output.setFocusable(false); // user can't get into output
JScrollPane scrollPane = new JScrollPane(output);
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
ActionListener inputListener = e -> {
String text = input.getText().trim();
if (text.isEmpty()) {
return;
}
output.append(text + "\n");
input.setText("");
input.requestFocusInWindow();
};
input.addActionListener(inputListener);
submitButton.addActionListener(inputListener);
JPanel bottomPanel = new JPanel();
bottomPanel.setLayout(new BoxLayout(bottomPanel, BoxLayout.LINE_AXIS));
bottomPanel.add(input);
bottomPanel.add(submitButton);
setLayout(new BorderLayout());
add(scrollPane, BorderLayout.CENTER);
add(bottomPanel, BorderLayout.PAGE_END);
}
private static void createAndShowGui() {
ChatBox mainPanel = new ChatBox();
JFrame frame = new JFrame("Chat Box");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
I want to construct a Swing component JTextField, here is my Code
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class JTextFieldGui{
JTextField textField;
JLabel labelInput;
JLabel labelOutput;
public static void main(String[] args) {
JTextFieldGui gui = new JTextFieldGui();
gui.go();
}
public void go(){
JFrame frame = new JFrame();
JPanel panelInput = new JPanel();
JPanel panelOutput = new JPanel();
labelInput = new JLabel("Your first name: ");
labelOutput = new JLabel("Enter your name, and you will see it here.");
textField = new JTextField(20);
JButton enter = new JButton("Enter");
JButton selectAll = new JButton("Select all text");
frame.setSize(300,200);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
panelInput.setLayout(new BoxLayout(panelInput, BoxLayout.X_AXIS));
textField.addActionListener(new LabelActionListener());
enter.addActionListener(new LabelActionListener());
selectAll.addActionListener(new TextFieldActionlistener());
frame.getContentPane().add(BorderLayout.NORTH, panelInput);
panelInput.add(labelInput);
panelInput.add(textField);
panelInput.add(enter);
panelInput.add(selectAll);
frame.getContentPane().add(BorderLayout.CENTER, panelOutput);
panelOutput.add(labelOutput);
}
class LabelActionListener implements ActionListener{
public void actionPerformed(ActionEvent event){
labelOutput.setText(textField.getText());
}
}
class TextFieldActionlistener implements ActionListener{
public void actionPerformed(ActionEvent event){
textField.selectAll();
}
}
}
Question1: I define the width of the text field in 20 columns, but it always take up a row, like image:
Question2: how to use the selectAll() method, I use it in a listener of the button selectAll, but when I click the button, nothing happens, why
I define the width of the text field in 20 columns, but it always take up a row,
This is the rule of a BoxLayout. A component is resized to fill the space available. A JTextField doesn't have a maximum size so it grows. The buttons and label do have a maximum size so they don't grow.
Don't use a BoxLayout, just use a FlowLayout. It will automatically leave space between each component which is a better layout.
I use it in a listener of the button selectAll, but when I click the button, nothing happens, why
Focus is still on the button. The selected text only displays when the text field has focus.
So in he listener code you need to add:
textField.requestFocusInWindow();
The following code is old:
frame.getContentPane().add(BorderLayout.NORTH, panelInput);
you don't need to get the content pane. You can just add the component to the frame.
the constraint should be the second parameter
there are new constraints to make the names more meaningful
So the code should be:
frame.add(panelInput, BorderLayout.PAGE_START, panelInput);
See the section from the Swing tutorial on How to Use BorderLayout for more information.
I'm trying to make a little game that will first show the player a simple login screen where they can enter their name (I will need it later to store their game state info), let them pick a difficulty level etc, and will only show the main game screen once the player has clicked the play button. I'd also like to allow the player to navigate to a (hopefully for them rather large) trophy collection, likewise in what will appear to them to be a new screen.
So far I have a main game window with a grid layout and a game in it that works (Yay for me!). Now I want to add the above functionality.
How do I go about doing this? I don't think I want to go the multiple JFrame route as I only want one icon visible in the taskbar at a time (or would setting their visibility to false effect the icon too?) Do I instead make and destroy layouts or panels or something like that?
What are my options? How can I control what content is being displayed? Especially given my newbie skills?
A simple modal dialog such as a JDialog should work well here. The main GUI which will likely be a JFrame can be invisible when the dialog is called, and then set to visible (assuming that the log-on was successful) once the dialog completes. If the dialog is modal, you'll know exactly when the user has closed the dialog as the code will continue right after the line where you call setVisible(true) on the dialog. Note that the GUI held by a JDialog can be every bit as complex and rich as that held by a JFrame.
Another option is to use one GUI/JFrame but swap views (JPanels) in the main GUI via a CardLayout. This could work quite well and is easy to implement. Check out the CardLayout tutorial for more.
Oh, and welcome to stackoverflow.com!
Here is an example of a Login Dialog as #HovercraftFullOfEels suggested.
Username: stackoverflow Password: stackoverflow
import java.awt.*;
import java.awt.event.*;
import java.util.Arrays;
import javax.swing.*;
public class TestFrame extends JFrame {
private PassWordDialog passDialog;
public TestFrame() {
passDialog = new PassWordDialog(this, true);
passDialog.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new TestFrame();
frame.getContentPane().setBackground(Color.BLACK);
frame.setTitle("Logged In");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
}
});
}
}
class PassWordDialog extends JDialog {
private final JLabel jlblUsername = new JLabel("Username");
private final JLabel jlblPassword = new JLabel("Password");
private final JTextField jtfUsername = new JTextField(15);
private final JPasswordField jpfPassword = new JPasswordField();
private final JButton jbtOk = new JButton("Login");
private final JButton jbtCancel = new JButton("Cancel");
private final JLabel jlblStatus = new JLabel(" ");
public PassWordDialog() {
this(null, true);
}
public PassWordDialog(final JFrame parent, boolean modal) {
super(parent, modal);
JPanel p3 = new JPanel(new GridLayout(2, 1));
p3.add(jlblUsername);
p3.add(jlblPassword);
JPanel p4 = new JPanel(new GridLayout(2, 1));
p4.add(jtfUsername);
p4.add(jpfPassword);
JPanel p1 = new JPanel();
p1.add(p3);
p1.add(p4);
JPanel p2 = new JPanel();
p2.add(jbtOk);
p2.add(jbtCancel);
JPanel p5 = new JPanel(new BorderLayout());
p5.add(p2, BorderLayout.CENTER);
p5.add(jlblStatus, BorderLayout.NORTH);
jlblStatus.setForeground(Color.RED);
jlblStatus.setHorizontalAlignment(SwingConstants.CENTER);
setLayout(new BorderLayout());
add(p1, BorderLayout.CENTER);
add(p5, BorderLayout.SOUTH);
pack();
setLocationRelativeTo(null);
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
addWindowListener(new WindowAdapter() {
#Override
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
jbtOk.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (Arrays.equals("stackoverflow".toCharArray(), jpfPassword.getPassword())
&& "stackoverflow".equals(jtfUsername.getText())) {
parent.setVisible(true);
setVisible(false);
} else {
jlblStatus.setText("Invalid username or password");
}
}
});
jbtCancel.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
setVisible(false);
parent.dispose();
System.exit(0);
}
});
}
}
I suggest you insert the following code:
JFrame f = new JFrame();
JTextField text = new JTextField(15); //the 15 sets the size of the text field
JPanel p = new JPanel();
JButton b = new JButton("Login");
f.add(p); //so you can add more stuff to the JFrame
f.setSize(250,150);
f.setVisible(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Insert that when you want to add the stuff in. Next we will add all the stuff to the JPanel:
p.add(text);
p.add(b);
Now we add the ActionListeners to make the JButtons to work:
b.addActionListener(this);
public void actionPerforemed(ActionEvent e)
{
//Get the text of the JTextField
String TEXT = text.getText();
}
Don't forget to import the following if you haven't already:
import java.awt.event*;
import java.awt.*; //Just in case we need it
import java.x.swing.*;
I hope everything i said makes sense, because sometimes i don't (especially when I'm talking coding/Java) All the importing (if you didn't know) goes at the top of your code.
Instead of adding the game directly to JFrame, you can add your content to JPanel (let's call it GamePanel) and add this panel to the frame. Do the same thing for login screen: add all content to JPanel (LoginPanel) and add it to frame. When your game will start, you should do the following:
Add LoginPanel to frame
Get user input and load it's details
Add GamePanel and destroy LoginPanel (since it will be quite fast to re-create new one, so you don't need to keep it memory).
I've looked around a while and also played around trying to add multiple panels to a JTabbedPane.
My question is: Is it possible to add the same Jpanel to multiple TabbedPanes. Everything way that I tried, it doesn't seem to work correctly. This is how it it works.
public MainGUI() {
JMenuBar menuBar = new JMenuBar();
setJMenuBar(menuBar);
JTabbedPane tabbedPane = new JTabbedPane(JTabbedPane.TOP);
getContentPane().add(tabbedPane, BorderLayout.CENTER);
JEditorPane instructionalEditorPane = new JEditorPane();
tabbedPane.addTab("Instructional", instructionalEditorPane);
JPanel codePanel = new JPanel();
JPanel drawPanel = new JPanel();
JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, codePanel, drawPanel);
splitPane.setResizeWeight(0.75);
tabbedPane.addTab("Code Panel", splitPane);
JEditorPane unifiedInstPane = new JEditorPane();
JPanel unifiedCodePanel = new JPanel();
JPanel unifiedDrawPanel = new JPanel();
JSplitPane unifiedSplitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, unifiedCodePanel, unifiedDrawPanel);
unifiedSplitPane.setResizeWeight(0.75);
JSplitPane unifiedPanel = new JSplitPane(JSplitPane.VERTICAL_SPLIT,unifiedInstPane, unifiedSplitPane);
unifiedPanel.setResizeWeight(0.40);
tabbedPane.addTab("Unified Tab", unifiedPanel);
}
What I would like to do is just add the instructionalEditorPane and the splitPane to multiple tabbedPanes but when I do I loose the original Individual tabbedPanes. If I have to I can do it this way but I would then have to write to both the unifiedInstPane & the instructionalEditorPane to keep them updated. I would also have to do this for the 2 splitPanes which have the codePanel and drawPanels embedded. This will make it harder to keep all the panels in sync.
Any suggestions?
"Is it possible to add the same Jpanel to multiple TabbedPanes." -- no. You can only add a component to one container at a time. Your JPanels should share models but use unique components. The model will likely be a non-GUI class of your creation.
For example, here's a very simplistic rendering of my recommendations:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import javax.swing.*;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
public class MainGui2 extends JPanel {
private static final int TAB_COUNT = 3;
private JTabbedPane tabbedPane = new JTabbedPane();
private PlainDocument doc = new PlainDocument();
private Action btnAction = new ButtonAction("Button");
public MainGui2() {
for (int i = 0; i < TAB_COUNT; i++) {
tabbedPane.add("Tab " + (i + 1), createPanel(doc, btnAction));
}
setLayout(new BorderLayout());
add(tabbedPane);
}
private JPanel createPanel(PlainDocument doc, Action action) {
JTextArea textArea = new JTextArea(doc);
textArea.setColumns(40);
textArea.setRows(20);
JPanel panel = new JPanel();
panel.add(new JScrollPane(textArea));
panel.add(new JButton(action));
return panel;
}
private class ButtonAction extends AbstractAction {
public ButtonAction(String title) {
super(title);
}
#Override
public void actionPerformed(ActionEvent evt) {
try {
String text = "Button Pressed!\n";
doc.insertString(doc.getLength(), text, null);
} catch (BadLocationException e) {
e.printStackTrace();
}
}
}
private static void createAndShowGui() {
JFrame frame = new JFrame("MainGui2");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new MainGui2());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
Better would be to create a formal model class that gets injected into each view, each tabbed pane's individual panes.
Edit
You state in comment:
Yes I can fix that by making calls to the instances but then I'm back to my original problem of having to make calls to each instance to affect a change in all the panel. Say for example I have a drawing panel and I need to call repaint(), I would have to make a call to 2 different instances to get both tabbedPanes to update. Is there any way around this?
Yes, the solution is to use an MVC, or model-view-control, structure. Your model holds your overall program logic, the views are what the user sees, and the control interacts between the two.
Consider having your model notify either the control or the views that its been changed, and then this stimulates a repaint an all observer views.