在控制台中输入特定行而不是整个JTextArea

Question

public class MatlabGui extends JPanel implements KeyListener {

    protected JTextArea myTextArea;;

    public MatlabGui() {
        super(new GridBagLayout());

        myTextArea = new JTextArea(50, 75);
        myTextArea.setEditable(true);
        JScrollPane myScrollPane = new JScrollPane(myTextArea);

        GridBagConstraints myCons = new GridBagConstraints();
        myCons.gridwidth = GridBagConstraints.REMAINDER;

        myCons.fill = GridBagConstraints.BOTH;
        myCons.weightx = 1;
        myCons.weighty = 1;
        add(myScrollPane, myCons);

        myTextArea.addKeyListener(this);

    }

    private static void createAndShowGUI() {
        JFrame frame = new JFrame("Matlab");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new MatlabGui());
        frame.pack();
        frame.setVisible(true);

    }

    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }

@Override
public void keyPressed(KeyEvent evt) {
    // TODO Auto-generated method stub
    if (evt.getKeyCode() == KeyEvent.VK_ENTER) {
        try {
            myTextArea.addCaretListener(CaretListener);
            int caretpos = myTextArea.getCaretPosition();
            int start = 0;
            int end = 0;

            start = myTextArea.getLineStartOffset(caretpos);
            end = myTextArea.getLineEndOffset(caretpos);

            System.out.println(myTextArea.getText(start, end));

        } catch (BadLocationException ex) {
            System.out.println(ex.getMessage());
        }
        myTextArea.append("\n" + ">>>" + " " + "matlab's response");
                }

}    
    public String getString() {
        return myTextArea.getText();
    }


    @Override
    public void keyReleased(KeyEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void keyTyped(KeyEvent arg0) {
        // TODO Auto-generated method stub
    }

}

Answer 1

对于您的另一个问题：

您的条件if(evt.getkeycode()==keyevent.vk_enter)在mytextarea.append（“\n”+“>>>”+“+”matlab的响应“）之前结束；所以当按下某个键时，总是调用mytestarea.append。

你应该做：

 if (evt.getKeyCode() == KeyEvent.VK_ENTER) {
        try {
            // Hint
            // offset=myTextArea.getLineOfOffset(myTextArea.getCaretPosition());
            int start = 0;
            int end = 0;
            start = myTextArea.getLineStartOffset(start);
            end = myTextArea.getLineEndOffset(end);

            System.out.println(myTextArea.getText(start, end));

        } catch (BadLocationException ex) {
            System.out.println(ex.getMessage());
        }

        String text = myTextArea.getText();
        System.out.println(text);

        myTextArea.append("\n" + ">>>" + " " + "matlab's response");
    }