java 如何从 JTextArea 获取文本？
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How to get text from JTextArea?
提问by razshan
I have a JTextArea on a JFrame and a JButton.
我在 JFrame 和 JButton 上有一个 JTextArea。
When user types characters on the JTextArea textArea and presses the button, I want the information to be saved in a textFile.
当用户在 JTextArea textArea 上键入字符并按下按钮时，我希望将信息保存在 textFile 中。
JTextArea textArea = new JTextArea(2, 20);
textArea.setLineWrap (true);
thehandler4 handler4 = new thehandler4(); // next button
button4.addActionListener(handler4);
private class thehandler4 implements ActionListener{ //next button
public void actionPerformed(ActionEvent event){
PrintWriter log = null;
try {
FileWriter logg =new FileWriter("logsheet.txt",true);
log = new PrintWriter(logg);
log.println("Quick Notes: "+textArea);
log.close();
} catch( Exception y ) { y.printStackTrace(); }
}}
But when I open the logsheet.txt, I don't see any thing. its null. is there a function I need like textArea.getText(); i tried that but I get an error.
但是当我打开 logsheet.txt 时，我什么也没看到。它的空值。有没有我需要的函数，比如 textArea.getText(); 我试过了，但出现错误。
回答by camickr
I'm guessing your problem is that you have your text area defined as a class varaible and a local variable. Your ActionListener is accessing the class variable which is null.
我猜您的问题是您将文本区域定义为类变量和局部变量。您的 ActionListener 正在访问为 null 的类变量。
//JTextArea textArea = new JTextArea(2, 20); // this is wrong, you don't want a local variable
textArea = new JTextArea(2, 20);
Also, using the textArea.write(...) method is the proper way to do this. You don't want to use the getText() method, because that approach may result in the wrong newline characters being contained in the string.
此外，使用 textArea.write(...) 方法是执行此操作的正确方法。您不想使用 getText() 方法，因为该方法可能会导致字符串中包含错误的换行符。
回答by Amokrane Chentir
You could do the following instead:
您可以改为执行以下操作：
JTextArea textArea = new JTextArea(2, 20);
FileWriter logg =new FileWriter("logsheet.txt",true);
textArea.write(logg);
The write() method allows you to write text from text area to a writer.
write() 方法允许您将文本区域中的文本写入编写器。
