Java JTextArea - 添加换行符 [英] Java JTextArea - Adding a newline

问题描述

所以我很难过。我出于某种原因似乎记得当你尝试添加新的东西时，Java会做出奇怪的事情......所以我认为这可能是问题所在。

So I'm stumped. I, for some reason, seem to remember that Java does weird things when you try to add new lines to stuff... so I think that may be the problem here.

此代码无法正常工作：

public void displayText(KeyEvent k){
    txt = inputArea.getText();
    outputArea.setText(txt);
    if(k.getKeyCode() == 10) //return
        outputArea.setText(txt + "\n");
}

您可以仔细检查我是否将getKeyCode（）设置为正确的数字，但我几乎肯定这部分是正确的。

You can double-check to see if I have the getKeyCode() set to the right number, but I'm almost positive that that part is correct.

编辑：
谢谢;我忘记了这些常数...

Thanks; I forgot about those constants...

不幸的是，它有效 - 但不是真的。 if（k.getKeyCode（）== k.VK_ENTER）返回true（这是事实），但\ n不会创建换行符。

And unfortunately, it works - but not really. if(k.getKeyCode() == k.VK_ENTER) returns true (this is a fact), but "\n" does not create the newline.

编辑（两个）：
完整代码：

EDIT (take two): Full code:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class GUI extends JFrame implements KeyListener{
    private JFrame frame;
    private JTextField inputArea;
    private JTextArea outputArea;
    private String txt;

    public GUI(){
        frame = new JFrame("My Frame");
        inputArea = new JTextField(1);
        outputArea = new JTextArea(5,10);
        inputArea.addKeyListener(this);
        outputArea.setLineWrap(true);
        txt = "";

        frame.setLayout(new GridLayout(2,10));
        frame.add(inputArea);
        frame.add(outputArea);
        frame.setVisible(true);
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public void keyPressed(KeyEvent k){}
    public void keyTyped(KeyEvent k){}

    public void keyReleased(KeyEvent k) {
        displayText(k);
    }

    public void displayText(KeyEvent k){
        txt = inputArea.getText();
        outputArea.setText(txt);
        if(k.getKeyCode() == KeyEvent.VK_ENTER)
            outputArea.append("\n");
            //outputArea.setText(txt + "\n");
    }
}

然后是另一个主要的类：

Then another class with the main:

public class Driver {
    public static void main(String[] args){ 
        GUI gui = new GUI();
    }
}

编辑：
基本上，我是试图模仿Google Wave在用户按下Enter键之前发送文本的能力。

Basically, I'm trying to emulate Google Wave's ability to send text before the user presses Enter.

推荐答案

编辑之后我看到你的完整代码，你的keylistener正在工作。问题是： outputArea.setText（txt）; 谁会覆盖您的换行符。尝试这样的事情：

After I see your full code, your keylistener is working. The problem is: outputArea.setText(txt); who overwrites your linebreaks. Try something like this:

public void displayText(KeyEvent k){
    txt = inputArea.getText();
    char key = k.getKeyChar();
    if(key != KeyEvent.VK_ENTER)
        outputArea.append(Character.toString(k.getKeyChar()));
    else {
        // do something special, then add a linebreak
        outputArea.append("\n");
    }
}

原始答案：试试使用getKeyChar（）而不是getKeyCode（）。请参见 http：//java.sun .com / j2se / 1.5.0 / docs / api / java / awt / event / KeyEvent.html 何时使用什么。此外，由于您只是在输入上进行测试，因此您可能不需要使用KeyListener。您可以在输入字段上使用ActionListener。请参阅下面的ActionListener和KeyListener解决方案的示例代码。

ORIGINAL ANSWER: Try using getKeyChar() instead of getKeyCode(). See http://java.sun.com/j2se/1.5.0/docs/api/java/awt/event/KeyEvent.html for when to use what. Also, since you are just testing on enter, you probarly won't need to use a KeyListener. You can use a ActionListener on the input-field instead. See sample code for both ActionListener and KeyListener solutions below.

public class JTextAreaTest extends JFrame{
private JTextArea txaConsole;
private JTextField txtInput;
private JButton btnSubmit;

public JTextAreaTest(){
    SubmitListener submitListener = new SubmitListener();
    MyKeyListener myKeyListener = new MyKeyListener();

    txaConsole = new JTextArea(10,40);
    txtInput = new JTextField();
    txtInput.addActionListener(submitListener);
    //txtInput.addKeyListener(myKeyListener);
    btnSubmit = new JButton("Add");
    btnSubmit.addActionListener(submitListener);

    add(new JScrollPane(txaConsole), BorderLayout.NORTH);
    add(txtInput, BorderLayout.CENTER);
    add(btnSubmit, BorderLayout.EAST);


    setDefaultCloseOperation(EXIT_ON_CLOSE);
    pack();
    setVisible(true);
    txtInput.requestFocusInWindow();
}

private void addInputToConsole(){
    String input = txtInput.getText().trim();
    if(input.equals("")) return;

    txaConsole.append(input + "\n");
    txtInput.setText("");
}

// You don't need a keylistener to listen on enter-presses. Use a
// actionlistener instead, as shown below.
private class MyKeyListener extends KeyAdapter {
    @Override
    public void keyTyped(KeyEvent e) {
        if(e.getKeyChar() == KeyEvent.VK_ENTER)
            addInputToConsole();
    }
}

private class SubmitListener implements ActionListener{
    @Override
    public void actionPerformed(ActionEvent e) {
        addInputToConsole();
    }
}

public static void main(String[] args) {
    new JTextAreaTest();
}
}

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