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SyntaxListener

    1 SyntaxListener methods
       1.1 Abstract methods to implement
       1.2 Asking for the document tokenization
    2 Adding the listener to the editor
    3 Example
    4 See also

The SyntaxListener interface allows to be notified from syntax events in the Code Editor component. It can be used for example to create a Popup menu depending on where the used clicks in the editor area.

SyntaxListener methods

The SyntaxListener interface has the following methods:

The SyntaxListener.documentUpdated(SyntaxDocument) is called when the editor is updated. It will be called when the content is set at the first time, or when content is added or removed
The SyntaxListener.startTokenize(SyntaxDocument) is called when the tokenization of the content starts
The SyntaxListener.startLine(int, int) is called when one line is tokenized
The SyntaxListener.startToken(int, int, Token) is called when a Token is detected during the tokenization of one Token
The SyntaxListener.endTokenize() is called when the tokenization of the content ends

The toknization will not be called automatically. It is the responsability of the SyntaxListener to call the SyntaxDocument.tokenizeLines() method to start the tokenization of the document content.

Abstract methods to implement

The only abstract methods which you have to implement are:

All the other methods have a default implementation which does nothing.

Asking for the document tokenization

The following methods are called during the document tokenization:

They will not be called automatically. It is the responsability of the SyntaxListener to call the SyntaxDocument.tokenizeLines() method to start the tokenization of the document content.

For example, it can be called when right-clicking on the editor background, if the document has been updated.

Adding the listener to the editor

The JEditor.setSyntaxListener(SyntaxListener) method adds a SyntaxListener to the Editor.

For example:

   JEditor editor = new JEditor();
   editor.setSyntax("xml");
   SyntaxListener listener = new SyntaxListenerImpl();
   editor.setSyntaxListener(listener);

Example

The following implementation just prints the content of each token which is notified to the listener:

   public class SyntaxListenerImpl implements SyntaxListener {
      private SyntaxDocument document;
      private boolean updated = false;

      public SyntaxListenerImpl() {
      }

      @Override
      public void documentUpdated(SyntaxDocument document) {
        this.document = document;
        updated = true;
      }

      public void tokenize() {
        if (updated) {
          document.tokenizeLines(); // call the tokenization of the document
          updated = false;
        }
      }

      @Override
      public void startToken(int lineIndex, int offset, Token token) {
        String message = "[lineIndex: " + lineIndex + ", offset:" + offset + ", token:" + token.getTokenName() + ", length:" + token.length + " : " + document.getTextProtected(offset, token.length) + "]";
        System.out.println(message);
      }
   }