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using listeners with both list and button

Very new to Java, but I am slowly picking my way through things. So please be kind. I understand most things I've tried so far, and built a version of the following that uses console output, but now I'm trying to make a GUI. I tried the netbeans GUI maker, but it created so much new code that when I tried to pick through it, I got lost. I'm much better at learning by piecing new things together myself, not having an IDE generate a ton of code and then attempt to find where I want to work.
I am trying to build an window that has a list with three choices on the left side, a button in the middle that confirms your choice, and an answer output on the right. Once the button is pressed, the input from the list is read and is converted into a corresponding answer. As of right now, all I get is "We recommend... null" after selecting an option in the list. The button appears to do nothing at the moment.
I have used tutorials, hacked up others' code from online, and referenced a few books, but I'm stuck.
Here is what I have:
package diffguidegui;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class DiffGuideGUI extends JPanel implements ListSelectionListener {
private JList resultsTabList;
private DefaultListModel listModel;
private static final String recommendString = "Recommend a Option";
private JButton recommendButton;
private String recommendOutput;
final JLabel output = new JLabel("We recommend..." + recommendOutput);
//build list
public DiffGuideGUI () {
super(new BorderLayout());
listModel = new DefaultListModel();
listModel.addElement("A");
listModel.addElement("B");
//create the list and put it in the scroll pane
resultsTabList = new JList(listModel);
resultsTabList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
resultsTabList.setSelectedIndex(0);
//listener for user input
resultsTabList.addListSelectionListener(this);
resultsTabList.setVisibleRowCount(2);
JScrollPane listScrollPane = new JScrollPane(resultsTabList);
//build the button at the bottom to fire overall behavior
recommendButton = new JButton(recommendString);
recommendButton.setActionCommand(recommendString);
recommendButton.addActionListener(new RecommendListener());
//create a panel that uses Boxlayout for the button
JPanel buttonPane = new JPanel();
buttonPane.setLayout(new BoxLayout(buttonPane, BoxLayout.LINE_AXIS));
buttonPane.add(recommendButton);
//create a panel that uses Boxlayout for the label
JPanel outputPane = new JPanel();
outputPane.setLayout(new BoxLayout(outputPane, BoxLayout.LINE_AXIS));
outputPane.add(output);
add(listScrollPane, BorderLayout.WEST);
add(buttonPane, BorderLayout.CENTER);
add(outputPane, BorderLayout.EAST);
}
//build listener class
class RecommendListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
//build in logic for choice made here
String resultsTabChoice;
resultsTabChoice = (String)resultsTabList.getSelectedValue();
if( resultsTabChoice.equals("A")) {
recommendOutput = "One";}
else {recommendOutput = "Two";}
}
}
public void valueChanged(ListSelectionEvent e) {
if(e.getValueIsAdjusting() == false) {
if(resultsTabList.getSelectedIndex() == -1) {
recommendButton.setEnabled(false);
} else {
recommendButton.setEnabled(true);
}
}
}
//Create GUI and show it
private static void createAndShowGUI() {
JFrame frame = new JFrame("Recommend Window");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//create and set up content pane
JComponent newContentPane = new DiffGuideGUI();
newContentPane.setOpaque(true);
frame.setContentPane(newContentPane);
//display the window
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}

The button appears to do nothing at the moment.
It does something. It calculates the value for your recommendOutput varable. But you never output this value.
try the following:
//build listener class
class RecommendListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
//build in logic for choice made here
String resultsTabChoice;
resultsTabChoice = (String)resultsTabList.getSelectedValue();
if( resultsTabChoice.equals("A")) {
recommendOutput = "One";}
else {recommendOutput = "Two";}
System.out.println(recommendOutput); // <-###################
}
}
This should print the value to stdout
To put the value into your label try this instead:
output.setText(recommendOutput);

where do you set the text for the JLabel? It says "We recommend NULL" because recommenedOutput is null when the object is created. I dont see
output.setText("We recommend "+value) anywhere. You probably need output.invalidate() also. Try putting setText(String text)/invalidate() in the RecommendListener.actionPerformed() method.
output.setText("We recommend A");
output.invalidate();

How to make a JList "refresh" method in a JPanel class

I'm a beginner at java and want to make a JFrame with tabs containing a seperate JPanel. One panel has a list where it displays things that you select in a different panel, so I want this panel to always display a list of stuff that you have selected in a different panel (I hope that makes sense). To do this, I need to make a method to refresh the JList. This is the Farthest that I've gotten on that:
public class PanelClass extends JPanel {
private JList list;
private DefaultListModel listModel = new DefaultListModel();
private ArrayList<SomeOtherClass> objectArray = new ArrayList<SomeOtherClass>();
public PanelClass() {
list.setModel(listModel);
}
public void refresh() {
updateListModel();
list.setModel(listModel);
}
public void updateListModel() {
if (objectArray.isEmpty()) {
System.out.println("No Objects In Array!");
} else {
listModel.clear();
for (SomeOtherClass SOC : objectArray) {
// SOC.getName() just returns a string
listModel.addElement(SOC.getName());
}
}
}
public void addObjectToArray(SomeOtherClass SOC) {
objectArray.add(SOC);
}
}
Could someone please tell me how to make a "refresh" method to constantly keep the JList up to date?

The AWT/Swing event model is based upon the widgets being event sources (in the MVC paradigm, they are both view and controller). Different widgets source different event types.
Look at the java.awt.event (primarily), and javax.swing.event packages for the listener interfaces you'll need to implement and register in order to produce your desired effect.
Basically, you write a Listener implementation, and register it with Widget1. When Widget1 detects an event, it will notify you, and you can then use the information it provides to update Widget2.
For instance, if a button being clicked would add an object to your list, you might have something like below (I usually put this code in the encompassing JFrame class, and make it implement the listener interfaces; but you can choose to use inner classes or separate listener classes):
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class MyFrame extends JFrame implements ActionListener {
private JButton button = new JButton("Click me!");
private DefaultListModel<String> listModel = new DefaultListModel<String>();
private JList<String> list = new JList<String>(listModel);
private int counter = 1;
public MyFrame() {
setTitle("Test Updates");
JTabbedPane tabs = new JTabbedPane();
add(tabs, BorderLayout.CENTER);
JPanel panel = new JPanel();
panel.add(list);
tabs.add("Selections", panel);
panel = new JPanel();
button.addActionListener(this);
panel.add(button);
tabs.add("Options", panel);
pack();
}
#Override
public void actionPerformed(final ActionEvent event) {
if (button.equals(event.getSource())) {
listModel.addElement("Item " + counter++);
}
}
/* Test it! */
public static void main(String[] args) {
final MyFrame frame = new MyFrame();
frame.addWindowListener(new WindowAdapter() {
#Override public void windowClosing(final WindowEvent e) {
frame.setVisible(false);
frame.dispose();
System.exit(0);
}
});
frame.setVisible(true);
}
}
This code sample is minimal, but it should give you an idea of how to go about implementing what you want.

You can do it in two way. First : Write it in infinite thread loop so that it will constantly update JList. Second : You can call refresh() method whenever new SOC objects are added in your ArrayList. It means you can call refresh() method from addObjectToArray() method which ultimately call the refresh method only when you have some change in your ArrayList.
FYI : I did it in my project and I went for second option.

JTree valueChanged event gets called before focusLost of another component on clicking a node

I have a JTree where each node of the tree represents some user data. The data is editable and is stored in a file/db. There are a bunch of JTextField that lets you edit/update the user data for the node. Saving of the data event is fired when JTextField loses the focus. This works fine except when you change the selection of the node in JTree. Because valueChanged of JTree event occurs before focusLost of JTextField.
Here is a SSCCE: http://pastebin.com/wH1Veqdc
public class JTreeFocusTest extends JFrame{
private static final long serialVersionUID = 1L;
public JTreeFocusTest() {
super("JTree Focus Test");
JPanel panel = new JPanel(true);
panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
MyTree tree = new MyTree();
panel.add(tree);
panel.add(Box.createVerticalStrut(20));
panel.add(new MyTextField(tree));
panel.add(Box.createVerticalStrut(20));
panel.add(new JTextField(30));
getContentPane().add(panel);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
}
public static void main(String[] args){
new JTreeFocusTest();
}
}
class MyTree extends JTree{
private static final long serialVersionUID = 1L;
public MyTree() {
DefaultMutableTreeNode root = new DefaultMutableTreeNode(new MyNode("Root", "Root"));
DefaultMutableTreeNode child1 = new DefaultMutableTreeNode(new MyNode("Child 1", "DOC122122"));
root.add(child1);
DefaultMutableTreeNode child2 = new DefaultMutableTreeNode(new MyNode("Child 2", "DOC134342"));
root.add(child2);
DefaultTreeModel model = new DefaultTreeModel(root, true);
setModel(model);
getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
setSelectionPath(getPathForRow(0));
}
}
class MyTextField extends JTextField implements FocusListener, TreeSelectionListener{
private static final long serialVersionUID = 1L;
private MyTree tree;
public MyTextField(MyTree tree) {
this.tree = tree;
setText("Some");
addFocusListener(this);
this.tree.addTreeSelectionListener(this);
Dimension dim = new Dimension(200, 20);
setPreferredSize(dim);
setMaximumSize(dim);
setMinimumSize(dim);
}
#Override
public void focusGained(FocusEvent e) {System.out.println("TextField gained focus");}
#Override
public void focusLost(FocusEvent e) {
getSelectedNodeUserObj().setValue(getText());
}
#Override
public void valueChanged(TreeSelectionEvent e) {
setText(getSelectedNodeUserObj().getValue());
}
private MyNode getSelectedNodeUserObj(){
return ((MyNode)((DefaultMutableTreeNode)this.tree.getSelectionPath().getLastPathComponent()).getUserObject());
}
}
class MyNode{
private String label = "";
private String value = "";
public MyNode(String label, String value) {
this.label = label;
this.value = value;
}
public void setValue(String value){
this.value = value;
}
public String getValue(){
return value;
}
public String toString(){
return label;
}
}
In this example I just have one field but in the actual application I have several fields that represents user data. Also JTextField is just an example, the input field could be JComboBox or JSpinner.
How can I save this user data? I'd appreciate any help/pointer.
Thanks!

Because valueChanged of JTree event occurs before focusLost of
JTextField.
this is logical ordering, don't to change that, one JComponents focusGained, then after focus owner focusLost in the Focus in Window
Focus is quite asyncronous, for JTextComponent can be delayed events firing from added Listeners/InputMask/Formatter, can be solved by delaying in invokeLater, forgot about that, not your issue
(I'm ...) remove TreeSelectionListener from JTextField, move to (logical) JTree,
add System.out.println(getText());, as 1st code line to public void valueChanged(TreeSelectionEvent e) {, see whats happend :-), there is place to store (use Runnable#Thread, SwingWorker to redirect whatever to Workers Thread)
then there stays question whats happend if value is/are changed in JTextField and user click to the same node, then value stays unchanged or JComponent are refreshed with original value, but this is about bussines logics, not about how to code, my speculation

I want to make a text field editable only when a check box is selected in Netbeans

I am using Netbeans, and I want it so a text field is only editable when the user clicks the check box. I have it so when they select the check box it makes the text field editable, but how do I make it so when they de-select the check box the text field becomes un-editable again?
The code I used to make it editable is -
private void chk4By6MouseClicked(java.awt.event.MouseEvent evt) {
txt4By6.setEditable(true);
}

Use ItemListener, so that you can enable or disable the JTextField depending on if JCheckBox is SELECTED or DESELECTED respectively.
A sample program :
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ModifyTextField
{
public static void createAndDisplayGUI()
{
JFrame frame = new JFrame("MODIFY TEXTFIELD");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationByPlatform(true);
final JPanel contentPane = new JPanel();
final JTextField tfield = new JTextField(10);
tfield.setEnabled(false);
final JCheckBox cbox = new JCheckBox("Enable TEXTFIELD", false);
ItemListener itemListener = new ItemListener()
{
public void itemStateChanged(ItemEvent ie)
{
tfield.setEnabled(ie.getStateChange() == ItemEvent.SELECTED)
}
};
cbox.addItemListener(itemListener);
contentPane.add(cbox);
contentPane.add(tfield);
frame.getContentPane().add(contentPane);
frame.pack();
frame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
createAndDisplayGUI();
}
});
}
}
Outcome :
and

See: http://docs.oracle.com/javase/tutorial/uiswing/events/actionlistener.html
Read the whole thing if you really want to learn how this works.

Have you considered:
private void chk4By6MouseClicked(java.awt.event.MouseEvent evt) {
txt4By6.setEditable(!txt4By6.isEditble());
}
Or maybe even... (assuming chk4By6 is a swing checkbox)
private void chk4By6MouseClicked(java.awt.event.MouseEvent evt) {
txt4By6.setEditable(chk4By6.isSelected());
}
And a third method might be:
private void chk4By6ActionPerformed(ActionEvent evt) {
txt4By6.setEditable(chk4By6.isSelected());
}

What text input component last had the focus?

Suppose I have a Java application that has more than one component in which you can enter text. Now suppose this application also has a dialog that lets you insert a single character (like the dialog in Word that comes up when you select Insert from the Edit menu) into those components. You want it to insert the character into whichever text component last had the focus.
But how do you know which text component last had the focus?
I could keep track of this manually, by having each text component report to the application whenever it gets the focus and then have the application insert the new character into whichever component that last had the focus.
But this must be a common problem (consider Paste buttons in tool bars---how does it know where to paste it into?). Is there something already built in to Swing that lets you get a handle to the last text component that had the focus? Or do I need to write this myself?

Is there something already built in to Swing that lets you get a handle to the last text component that had the focus?
You create an Action that extends TextAction. The TextAction class has a method that allows you to obtain the last text component that had focus.
Edit:
You can create your own Action and do whatever you want. The Action can then be added to any JMenuItem or JButton. For example:
class SelectAll extends TextAction
{
public SelectAll()
{
super("Select All");
}
public void actionPerformed(ActionEvent e)
{
JTextComponent component = getFocusedComponent();
component.selectAll();
}
}
If you just want to insert a character at the caret position of the text field then you can probably just do
component.replaceSelection(...);
Edit 2:
I don't understand what the confusion is with this answer. Here is a simple example:
select some text
use the mouse to click on the check box
tab or use the mouse to click on the "Cut" button
It doesn't matter that the text field doesn't currently have focus when the Action is invoked. The TextAction tracks the last text component that had focus.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class TextActionTest extends JFrame
{
JTextField textField = new JTextField("Select Me");
JTabbedPane tabbedPane;
public TextActionTest()
{
add(textField, BorderLayout.NORTH);
add(new JCheckBox("Click Me!"));
add(new JButton(new CutAction()), BorderLayout.SOUTH);
}
public static void main(String[] args)
{
TextActionTest frame = new TextActionTest();
frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
frame.pack();
frame.setLocationRelativeTo( null );
frame.setVisible(true);
}
class CutAction extends TextAction
{
public CutAction()
{
super("Click to Cut Text");
}
public void actionPerformed(ActionEvent e)
{
JTextComponent component = getFocusedComponent();
// JTextComponent component = getTextComponent(e);
component.cut();
}
}
}

Just like suggested by #lesmana (+1 for that).
Here you have an example that shows that on focusLost the focus listener returns the previously focused component.
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class Focusing
{
public static void main(String[] args)
{
JPanel p = new JPanel();
JTextField tf1 = new JTextField(6);
tf1.setName("tf1");
p.add(tf1);
JTextField tf2 = new JTextField(6);
tf2.setName("tf2");
p.add(tf2);
FocusListener fl = new FocusListener()
{
#Override
public void focusGained(FocusEvent e)
{
System.out.println("focusGained e.getSource().c=" + ((JComponent) e.getSource()).getName());
}
#Override
public void focusLost(FocusEvent e)
{
System.out.println("focusLost e.getSource().c=" + ((JComponent) e.getSource()).getName());
}
};
tf1.addFocusListener(fl);
tf2.addFocusListener(fl);
JPanel contentPane = new JPanel();
contentPane.add(p);
JFrame f = new JFrame();
f.setContentPane(contentPane);
f.setSize(800, 600);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
}
All the best, Boro.

I've never done this directly, but you could look into the FocusEvents and the Focus Subsystem.
Hopefully there is something in the Focus Subsystem that would fire events that you could listen for.

You can register a FocusListener to every text component. The FocusEvent object has a reference to the last component which had focus.