documentFilter.insert从未调用过 [英] documentFilter.insert never called

问题描述

我正在尝试为我的JTextArea设置documentFilter。覆盖插入（...）方法后，我承认它永远不会被调用。怎么了？一段代码：

I'm trying to set a documentFilter for my JTextArea. Having overriden the insert(...) method I admitted that it is never called. What's wrong? A piece of code:

package jaba;

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

public class Main extends JFrame {
    public Main() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(640, 480);
        setLayout(new FlowLayout());
        add(txt);
        Document doc = txt.getDocument();
        if (doc instanceof AbstractDocument) {
            ((AbstractDocument)doc).setDocumentFilter(new DocumentFilter() {
                @Override
                public void insertString(DocumentFilter.FilterBypass fb, 
                        int offset, String string, AttributeSet att)
                throws BadLocationException {
                    if (string.toLowerCase().contains("ass")) {
                        super.insertString(fb, offset, "###", att);
                    } else {
                        super.insertString(fb, offset, string, att);
                    }
                }
            });
        } else {
            txt.setText("error setting filter");
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new Main().setVisible(true);
            }
        });
    }

    private JTextArea txt = new JTextArea(40, 40);
}

推荐答案

覆盖插入（...）方法后，我承认它永远不会被调用。

Having overriden the insert(...) method I admitted that it is never called.

最终对Swing组件中的文本进行更改调用DocumentFilter的replace（...）方法。

Changes to the text in Swing components ultimately invoke the replace(...) method of the DocumentFilter.

只有在使用以下代码直接更新Document时才会调用insertString（...）方法：

The insertString(...) method is only invoked when you update the Document directly by using code like:

textField.getDocument().insertString(...);

所以你需要确保你也覆盖了DocumentFilter中的replace（）方法。

So you need to make sure that you also override the replace() method in the DocumentFilter.

这篇关于documentFilter.insert从未调用过的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！