how to access jtextarea from one jframe to other jframe

Question

im having 2 jframes.in 1 jframes,i am giving input in jtextarea,that should be displayed in another jframe jtextarea.how can i get that. im using netbeans,i have designed jframes using swing. can anyone help me.

Answer 1

您可能只是在两个文本组件之间共享相同的Document实例： thisTextArea.setDocument(thatTextArea.getDocument())

Answer 2

The following code perhaps illustrates that better than any cryptic explanation that previously stood above: :)

public class SourceFrame extends JFrame {

    private final JTextArea sourceArea = new JTextArea();
    private TargetFrame targetFrame; // somehow set this one

    public void addDocumentListener(DocumentListener listener) {
        sourceArea.getDocument().addDocumentListener(listener);
    }

    public void removeDocumentListener(DocumentListener listener) {
        sourceArea.getDocument().removeDocumentListener(listener);
    }

}

public class TargetFrame extends JFrame {

    private final JTextArea targetArea = new JTextArea();
    private final SourceFrame sourceFrame; 

    public void init() {
        sourceFrame.addDocumentListener(new DocumentListener() {
            public void changedUpdate(DocumentEvent event) {
                Document doc = event.getDocument();
                targetArea.setText(doc.getText(0, doc.getLength()));
            }
            public void insertUpdate(DocumentEvent event) {
                Document doc = event.getDocument();
                targetArea.setText(doc.getText(0, doc.getLength()));
            }
            public void removeUpdate(DocumentEvent event) {
                Document doc = event.getDocument();
                targetArea.setText(doc.getText(0, doc.getLength()));
            }
        }
    }

}

Ideally, one would have a public method for setting the text in TargetFrame and implement the listener somewhere else so none of both frames does need to reference the other one.

Answer 3

The proper way to do this is using the Observer pattern (also called listener). Generally, the two main frame shouldn't know of the dependent frame. It should provide a way for notification whoever is interested . So in code:

public class SourceFrame extends JFrame {

    private final JTextArea sourceArea = new JTextArea();
    private TargetFrame targetFrame; // somehow set this one

    public void addTextChangeKeyListener(KeyListener listener) {
         sourceArea.addKeyListener(listener);
    }
    // a method to remove the listener might be required as well
}

And then in the TargetFrame you subscribe for key events that occur in the source text area:

public class TargetFrame extends JFrame {
    private final JTextArea targetArea = new JTextArea();
    private SourceFrame sourceFrame; // set this via constructor

    // this is called on initialization, perhaps from the constructor. 
    // Check what NetBeans has generated
    public void init() {
        sourceFrame.addDocumentListener(new DocumentListener() {
        public void changedUpdate(DocumentEvent event) {
            Document doc = event.getDocument();
            targetArea.setText(doc.getText(0, doc.getLength()));
        }
        public void insertUpdate(DocumentEvent event) {
            Document doc = event.getDocument();
            targetArea.setText(doc.getText(0, doc.getLength()));
        }
        public void removeUpdate(DocumentEvent event) {
            Document doc = event.getDocument();
            targetArea.setText(doc.getText(0, doc.getLength()));
        }
    }
}

The e.getSource() returns the component that created the event.