使用KeyListener for Java与多个文本字段进行交互 [英] Interacting with multiple textfields with KeyListener for Java

问题描述

我正在制作一个小型Java程序，其中有两个标记为field1，field2的JTextField.我还有一个计算"按钮，最初将其设置为禁用".我希望仅在2个文本框中包含值时才启用按钮.目前，我为关键侦听器提供的是:

I'm making a small java program where I have two JTextFields labeled field1, field2. I have a calculate button as well which initially set to disabled. I want the button only to be enabled when the 2 text boxes have values in them. Currently what i have for the key listener is:

field1.addKeyListener(new java.awt.event.KeyAdapter()  {  
public void keyReleased(java.awt.event.KeyEvent evt) {  
        if (field1.getDocument().getLength() > 0) {  
            bt1.setEnabled(true);
            }
        else {  
            bt1.setEnabled(false);  
        }  
    }
}); 

有没有一种方法可以将字段2包含在上面的代码块中?我试过两次复制和粘贴相同的代码块，但是将field1更改为field2，但这仍然行不通.

Is there a way to include field 2 into the above block? I've tried just copying and pasting the same code block twice but changing the field1 to field2 but that still doesn't work.

感谢您的帮助

推荐答案

您当前的要求可能仅是两个文本字段，但是您应该始终设计得更加灵活，并允许任意数量的文本字段.这也使代码可以重用.

You current requirement may be for only two text fields, but you should always design to be more flexible and allow any number of text fields. This also allows the code to be reusable.

类似的东西:

import java.awt.*;
import java.awt.event.*;
import java.util.List;
import java.util.ArrayList;
import javax.swing.*;
import javax.swing.event.*;

public class DataEntered implements DocumentListener
{
    private JButton button;
    private List<JTextField> textFields = new ArrayList<JTextField>();

    public DataEntered(JButton button)
    {
        this.button = button;
    }

    public void addTextField(JTextField textField)
    {
        textFields.add( textField );
        textField.getDocument().addDocumentListener( this );
    }

    public boolean isDataEntered()
    {
        for (JTextField textField : textFields)
        {
            if (textField.getText().trim().length() == 0)
                return false;
        }

        return true;
    }

    @Override
    public void insertUpdate(DocumentEvent e)
    {
        checkData();
    }

    @Override
    public void removeUpdate(DocumentEvent e)
    {
        checkData();
    }

    @Override
    public void changedUpdate(DocumentEvent e) {}

    private void checkData()
    {
        button.setEnabled( isDataEntered() );
    }

    private static void createAndShowUI()
    {
        JButton submit = new JButton( "Submit" );
        submit.setEnabled( false );

        JTextField textField1 = new JTextField(10);
        JTextField textField2 = new JTextField(10);

        DataEntered de = new DataEntered( submit );
        de.addTextField( textField1 );
        de.addTextField( textField2 );

        JFrame frame = new JFrame("SSCCE");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(textField1, BorderLayout.WEST);
        frame.add(textField2, BorderLayout.EAST);
        frame.add(submit, BorderLayout.SOUTH);
        frame.pack();
        frame.setLocationByPlatform( true );
        frame.setVisible( true );
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowUI();
            }
        });
    }
}

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