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How to Add text to JTextArea

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

How to display one Jframe at a time? [duplicate]

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).

How to use DefaultEditorKit in an AbstractAction

My notepad program that I'm writing uses AbstractActions for each item in the JMenuBar, and I want to keep it consistent that way throughout my code. And now I'm implementing Cut, Copy, Paste into the program but I'm unsure of how to do that with Action.
import java.awt.*;
import java.awt.event.ActionEvent;
import javax.swing.*;
import javax.swing.text.DefaultEditorKit;
public class Home {
static Action Cut = new AbstractAction("Cut-Action") {
public void actionPerformed(ActionEvent e) {
// Where I want to use cut
new DefaultEditorKit.CutAction();
}
};
static public JMenuBar createMenuBar() {
JMenuBar menuBar = new JMenuBar();
JMenu menu = new JMenu("Edit");
menu.add(Cut); // Adds the cut action
// adds the non-action method
JMenuItem item = new JMenuItem(new DefaultEditorKit.CutAction());
item.setText("Cut-NonAction");
menu.add(item);
menuBar.add(menu);
return menuBar;
}
public static void main(String[] args) {
JFrame frame = new JFrame("Home");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JMenuBar menuBar = createMenuBar();
frame.add(menuBar, BorderLayout.NORTH);
JTextPane txt = new JTextPane();
JScrollPane s = new JScrollPane(txt);
frame.add(s, BorderLayout.CENTER);
frame.setSize(400, 300);
frame.setVisible(true);
}
}
How would I be able to use the cut action in my abstract action??

I figured it out with a little bit of trial and error.
I changed this code:
public void actionPerformed(ActionEvent e) {
new DefaultEditorKit().CutAction();
}
to:
public void actionPerformed(ActionEvent e) {
Action cut = new DefaultEditorKit.CutAction();
cut.actionPerformed(e);
}

How would I be able to use the cut action in my abstract action??
Why are you trying to do this? The is not the way to use the Actions from the editor kit.
This is the proper way to use the actions:
JMenuItem item = new JMenuItem(new DefaultEditorKit.CutAction());
Or if you happen to need the CutAction on a menu and on a toolbar you would use code like:
Action cut = new DefaultEditorKit.CutAction();
cut.putValue(Action.NAME, "Cut");
JMenuItem cutMenuItem = new JMenuItem( cut );
JButton cutButton = new JButton( cut );
Now the same Action is shared which means you can enable/disable the Action and both components will be affected. Read the section from the Swing tutorial on How to Use Actions for more information and examples.

Putting multiple JPanels inside a JTabbed pane

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.

JFrame's getFocusOwner() not being helpful

I am working with a Swing program and having a little trouble. The program has two windows (both are JFrames). The main window is just fine and should not be relevant to this issue.
The window I am having issues with contains a JScrollPane with a JPanel in it, and has a JMenuBar. The JPanel has a bunch of JTextComponents (some JTextFields, some JTextAreas) on it.
What I want to do is have an ActionListener attached to a JMenuItem find the JTextComponent that has focus.
I have seen the previous posts at focused component reference and How to find out which object currently has focus. My issue is that calling the particular window's getFocusOwner() method merely returns the JFrame's JRootPane, which is utterly unhelpful. Both the JScrollPane and the JPanel in question are focusable according to their isFocusable() methods. This happens even if I actually enter text into one of the JTextComponents before clicking the menu item. The cursor still blinks in the text field while I open the menu, and everything. For what it's worth, getMostRecentFocusOwner() also simply returns the JRootPane.

If you use TextActions, the action knows which JTextComponent has the focus. I've modified some code that I found here to show that even if the TextActions come from one JTextArea, they still will automatically work on any and all text components that have focus:
import java.awt.GridLayout;
import javax.swing.*;
public class TextActionExample {
public static void main(String[] args) {
// Create a text area.
JTextArea ta = new JTextArea(15, 30);
ta.setLineWrap(true);
// Add all actions to the menu (split into two menus to make it more
// usable).
Action[] actions = ta.getActions();
JMenuBar menubar = new JMenuBar();
JMenu actionmenu = new JMenu("Actions");
menubar.add(actionmenu);
JMenu firstHalf = new JMenu("1st Half");
JMenu secondHalf = new JMenu("2nd Half");
actionmenu.add(firstHalf);
actionmenu.add(secondHalf);
int mid = actions.length / 2;
for (int i = 0; i < mid; i++) {
firstHalf.add(actions[i]);
}
for (int i = mid; i < actions.length; i++) {
secondHalf.add(actions[i]);
}
JTextField textField = new JTextField(20);
JPanel textFieldPanel = new JPanel();
textFieldPanel.add(textField);
JPanel mainPanel = new JPanel(new GridLayout(1, 0, 5, 5));
mainPanel.add(new JScrollPane(ta));
mainPanel.add(new JScrollPane(new JTextArea(15, 30)));
mainPanel.add(textFieldPanel);
// Show it . . .
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().add(mainPanel);
f.setJMenuBar(menubar);
f.pack();
f.setVisible(true);
}
}
This is very interesting stuff that I have to learn more about.

I think I have solved this, because of the fact that you lose focus when you click on a menu item, we simply have to wait for focus to return to the component before we check who has focus, I have done this using a swing timer that waits 100ms and then executes its method to check which component has focus:
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.TimerTask;
import javax.swing.*;
public class JavaApplication180 extends JFrame {
private JTextField[] JTextFields;
private JMenuBar menuBar;
private JMenu menu;
private JMenuItem item;
public JavaApplication180() {
initComponents();
createAndShowUI();
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new JavaApplication180();
}
});
}
private void createAndShowUI() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
getContentPane().setLayout(new GridLayout(2, 2, 10, 10));
setJMenuBar(menuBar);
addComponentsToPane();
pack();
setVisible(true);
}
private void initComponents() {
JTextFields = new JTextField[4];
menuBar = new JMenuBar();
item = new JMenuItem("Who has focus?");
item.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
TimerTask tt = new TimerTask() {
#Override
public void run() {
JOptionPane.showMessageDialog(null, getMostRecentFocusOwner().getName());
}
};
new java.util.Timer().schedule(tt, 100);
}
});
menu = new JMenu("File");
menu.add(item);
menuBar.add(menu);
}
private void addComponentsToPane() {
for (int i = 0; i < JTextFields.length; i++) {
JTextFields[i] = new JTextField();
JTextFields[i].setText(String.valueOf(i));
JTextFields[i].setName(String.valueOf(i));
getContentPane().add(JTextFields[i]);
}
}
}

I'm probably too late, but I just did the following in my JFrame constructor.
this.rootPane.setFocusable(false);
Now
getFocusOwner()
will return the current JTextComponent instead of the rootPane.
I then used this code in an ActionListener attached to my JMenuItem to select the text within it.
if (getFocusOwner() instanceof JTextField)
{
((JTextField) getMostRecentFocusOwner()).selectAll();
}
It should be noted that If you have a JScrollPane etc, you may have to use setFocusable(false) on all the components between the rootPane and the textfields.
Hope this helps anyone else with the same issue!
Source: Personal Experience

When I've needed this, I wrote a focus listener. I had a JPanel with two columns of JTextFields and the focus listener kept track of which column was last used by the user. I enablesd the user to enter some text into that last focused column with a button click. You would use just one instance of your FocusListener for all text fields and have a field referencing the most recently focused component. Your menu action can then query that field to determine which text field to use.
See http://docs.oracle.com/javase/tutorial/uiswing/events/focuslistener.html