请查看以下3组课程。请注意，仅显示相关代码，而其余大部分则被删除。
CommonGUI.java
package normal;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import javax.swing.*;
import javax.swing.text.AbstractDocument;
public class CommonGUI extends JPanel
{
protected JLabel name, mobileNumber1, mobileNumber2, address, landNumber1, landNumber2, nickName, email, category;
protected JTextField nameTxt, mobileNumber1Txt, mobileNumber2Txt, landNumber1Txt, landNumber2Txt, nickNameTxt, emailTxt, categoryTxt;
protected JTextArea addressTxt;
protected JScrollPane scroll;
protected JComboBox categoryCombo;
public CommonGUI()
{
//Intializing the instance variables
name = new JLabel("Name: ");
mobileNumber1 = new JLabel("Mobile Number 1:");
mobileNumber2 = new JLabel("Mobile Number 2: ");
address = new JLabel("Address: ");
landNumber1 = new JLabel("Land Number 1: ");
landNumber2 = new JLabel("Land Number 2: ");
nickName = new JLabel("Nick Name: ");
email = new JLabel("Email: ");
category = new JLabel("Category: ");
nameTxt = new JTextField(10);
mobileNumber1Txt = new JTextField(10);
mobileNumber2Txt = new JTextField(10);
addressTxt = new JTextArea(5,20);
landNumber1Txt = new JTextField(10);
landNumber2Txt = new JTextField(10);
categoryTxt = new JTextField();
nickNameTxt = new JTextField(10);
emailTxt = new JTextField(10);
categoryCombo = new JComboBox();
//Adding document listeners to text fields
AbstractDocument[]d = new AbstractDocument[8];
d[0] = (AbstractDocument) nameTxt.getDocument();
d[1] = (AbstractDocument) mobileNumber1Txt.getDocument();
d[2] = (AbstractDocument) mobileNumber2Txt.getDocument();
d[3] = (AbstractDocument) addressTxt.getDocument();
d[4] = (AbstractDocument) landNumber1Txt.getDocument();
d[5] = (AbstractDocument) landNumber2Txt.getDocument();
d[6] = (AbstractDocument) categoryTxt.getDocument();
d[7] = (AbstractDocument) nickNameTxt.getDocument();
d[0].setDocumentFilter(new TextFieldValidator(nameTxt,20));
d[1].setDocumentFilter(new TextFieldValidator(mobileNumber1Txt,10));
d[2].setDocumentFilter(new TextFieldValidator(mobileNumber2Txt,10));
d[3].setDocumentFilter(new TextFieldValidator(addressTxt,100));
d[4].setDocumentFilter(new TextFieldValidator(landNumber1Txt,10));
d[5].setDocumentFilter(new TextFieldValidator(landNumber2Txt,10));
d[6].setDocumentFilter(new TextFieldValidator(categoryTxt,20));
d[7].setDocumentFilter(new TextFieldValidator(nickNameTxt,20));
}
}
UpdateDeleteForm.java
//Following class get fired when an "category" is selected from the JComboBox. Rest of the code is ommited
private class DetailsLoader implements ItemListener
{
public void itemStateChanged(ItemEvent ie)
{
if(ie.getStateChange()==ItemEvent.SELECTED)
{
List details = new ArrayList();
if(nameTxtCombo.getSelectedItem().toString() != "Select a Name")
{
details = dateBaseConnector.getDetails(nameTxtCombo.getSelectedItem().toString());
String address = (String)details.get(6);
idTxt.setText(String.valueOf(details.get(0)));
nameTxt.setText((String)details.get(1));
mobileNumber1Txt.setText(String.valueOf(details.get(2)));
mobileNumber2Txt.setText(String.valueOf(details.get(3)));
landNumber1Txt.setText(String.valueOf(details.get(4)));
landNumber2Txt.setText(String.valueOf(details.get(5)));
addressTxt.setText(address.trim());
//categoryCombo.setSelectedItem((String)details.get(7));
nickNameTxt.setText((String)details.get(8));
emailTxt.setText((String)details.get(9));
}
}
}
}
TextFieldValidator.java
package normal;
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
import javax.swing.text.JTextComponent;
public class TextFieldValidator extends DocumentFilter
{
private JTextComponent textField;
private int numberOfLetters;
public TextFieldValidator(JTextComponent text, int i)
{
textField = text;
numberOfLetters = i;
}
@Override
public void insertString(FilterBypass fb, int offset, String string, AttributeSet attr) throws BadLocationException
{
if(fb.getDocument().getLength()+string.length()>numberOfLetters)
{
return;
}
super.insertString(fb, offset, string, attr);
}
@Override
public void remove(FilterBypass fb, int offset, int length) throws BadLocationException
{
fb.remove(offset, length);
}
@Override
public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException
{
if(fb.getDocument().getLength()+text.length()>numberOfLetters)
{
return;
}
super.insertString(fb, offset, text, attrs);
}
}
现在，当我选择一个类别时，它将根据该类别中选择的项目填充其他文本字段。但是，当我添加documentListener来添加验证时，setText（）方法的行为异常。这意味着可以想象一下
第一次-从类别中选择“大学”。它将nameTxt框填充为“ Yohan”
第二次-现在您需要查看另一个，从类别中选择“学院”。现在，它应该在Txt名称中显示“ Brian”，但是，它仍然显示了“ Brian Yohan”。嗯..“ Yohan”尚未从文本字段中删除！
当我从验证中删除documentListener时，一切正常，没有错误。因此，我相信这与documentListener有关。请帮忙！！
最佳答案
问题是您的replace方法：
@Override
public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException
{
if(fb.getDocument().getLength()+text.length()>numberOfLetters)
{
return;
}
super.insertString(fb, offset, text, attrs);
}
您在这里呼叫
super.insertString而不是呼叫super.replace。您的setText调用将调用此replace方法，并最终插入文本而不是替换文本。关于java - DocumentListener在JTextField.setText()中出现问题，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/12112694/