CODEWITHSUNDEEP
javaswingeventsjtextfieldjtextcomponent
Tomáš Zato
Tomáš Zato

Reputation: 53129

Trigger event while typing in a JTextComponent java

I have a Settings class that should provide interface for retrieving settings and saving them to a file. My settings are supposed to update whenever I change input values (rather than after clicking Save button). This is why I added this method to Settings class:

  /** Automatically update setting value as user types.
   * @param setting_name What is the name of associated setting?
   * @param input JTextComponent (like JTextField) to listen on for events
   */
  public void listenOnInput(final String setting_name, final JTextComponent input) {
    //Debug output
    System.out.println("Settings[\""+setting_name+"\"] automatically updates on input change.");
    input.addInputMethodListener(new InputMethodListener() {
      @Override
      public void inputMethodTextChanged(InputMethodEvent event) {
        //Set setting to current value
        setSetting(setting_name, input.getText());
      }
      //This method is dummy, I see no use for it
      @Override
      public void caretPositionChanged(InputMethodEvent event) {}
    });
  }

It's probably not perfect design, but my application will never have complex settings therefore I don't put so much effort in this task. I use it like this:

    JTextField name = new JTextField();
    Settings settings = new Settings();
    name.setToolTipText("Enter your name");
    contentPane.add(name);
    settings.listenOnInput("user_name", name);

My problem is that the code above doesn't work - I can type or press Enter but the inputMethodTextChanged is never called.

So what's proper method of obtaining the value on update?

Upvotes: 0

Views: 1895

Answers (1)

osechet
osechet

Reputation: 466

Use a DocumentListener on the JTextField's document:

textField.getDocument().addDocumentListener(...);

You can then use it to detect any change in the text.

Upvotes: 2

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