如何保存JTextArea文本？

Question

I would like to know how to save JTextArea text that when user types something in area it stays there even when user exits the program and re-opens it.

Sorry for my bad english and grammar.

Answer 1

There are multiple ways to do this.

1. Use a database: You can store many different inputs in the database, and link it to the user who made the input, or anything else.
2. Write to a .txt file: This allows you to access the data from outside your application very easily.
3. Serialize String: You could save the text in a String and serialize the Object.

There are many ways to do it, hard to determine which is the best, as we do not know what you want to achieve.

Answer 2

In general, you probably want to use Swing components to expose fields in some "model" object, and save the model (to a database, file, etc.) only on explicit user action, but also save it to some user-private place on every user action ("auto-save"). However, java.util.prefs.Preferences may be useful for exactly what you're asking. A simple example (untested):

public class SwingPrefsDemo extends JFrame {
  // other fields, etc...
  Preferences prefsNode = Preferences.userNodeForPackage(SwingPrefsDemo.class);
  JTextField tf_ta;

  public SwingPrefsDemo() {
    // ...
    tf_ta = new JTextArea();
    tf_ta.setText(prefsNode.get("tf_ta","enter text here"));
    this.add(tf_ta);
    tf_ta.getDocument().addDocumentListener(new DocumentListener() {
      public void changedUpdate(DocumentEvent evt) { change(); }
      public void insertUpdate(DocumentEvent evt) { change(); }
      public void removeUpdate(DocumentEvent evt) { change(); }
      private void change() {
        prefsNode.put("tf_ta",tf_ta.getText());
      }});
  } 
}