StackOverflow2013

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copied!<p>I would consider using a DocumentListener that listens to the Documents held by the JTextFields. There are examples of this sort of thing on this site (I know, because I've written one or two).</p> <p>For example,</p> <pre><code>import java.awt.Component; import java.util.ArrayList; import java.util.List; import javax.swing.*; import javax.swing.event.*; import javax.swing.text.JTextComponent; public class DocumentListenerFun extends JPanel { private static final int FIELD_COUNT = 5; private JTextField[] fields = new JTextField[FIELD_COUNT]; private JButton fooBtn = new JButton("Foo"); private JButton barBtn = new JButton("Bar"); private MyFieldListener myFieldListener = new MyFieldListener(); public DocumentListenerFun() { fooBtn.setEnabled(false); barBtn.setEnabled(false); for (int i = 0; i < fields.length; i++) { fields[i] = new JTextField(10); add(fields[i]); myFieldListener.addTextComponent(fields[i]); } myFieldListener.addComponentsToEnable(fooBtn); myFieldListener.addComponentsToEnable(barBtn); add(fooBtn); add(barBtn); } private static void createAndShowGui() { DocumentListenerFun mainPanel = new DocumentListenerFun(); JFrame frame = new JFrame("DocumentListenerFun"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(mainPanel); frame.pack(); frame.setLocationByPlatform(true); frame.setVisible(true); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGui(); } }); } } class MyFieldListener { private List<JTextComponent> textComponents = new ArrayList<JTextComponent>(); private List<Component> componentsToEnable = new ArrayList<Component>(); private MyDocListener myDocListener = new MyDocListener(this); public void addTextComponent(JTextComponent textComponent) { textComponents.add(textComponent); textComponent.getDocument().addDocumentListener(myDocListener); } public void addComponentsToEnable(Component comp) { componentsToEnable.add(comp); } public void docsChanged() { boolean textVerified = true; for (JTextComponent textComp : textComponents) { String text = textComp.getText(); textVerified &= verifyText(text); } for (Component comp : componentsToEnable) { comp.setEnabled(textVerified); } } private boolean verifyText(String text) { try { int value = Integer.parseInt(text.trim()); if (value > 0) { return true; } } catch (NumberFormatException e) { return false; } return false; } } class MyDocListener implements DocumentListener { private MyFieldListener myFieldListener; public MyDocListener(MyFieldListener myFieldListener) { this.myFieldListener = myFieldListener; } @Override public void changedUpdate(DocumentEvent e) { myFieldListener.docsChanged(); } @Override public void insertUpdate(DocumentEvent e) { myFieldListener.docsChanged(); } @Override public void removeUpdate(DocumentEvent e) { myFieldListener.docsChanged(); } } </code></pre>

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