有没有办法只接受JTextField中的数值？

Question

有没有办法只接受JTextField中的数值？这有什么特别的方法吗？

Answer 1

由于这个问题经常出现，我在这个答案中付出了更多的努力，然后我会这么做。

我的投票是JFormattedTextField。 IMO每个Swing开发人员都应该在他/她的工具包中拥有该类的改进版本，因为它允许通过正确选择Format来验证您能想到的几乎任何内容。我已经使用过它的例子：

• String可能不为空的字符串输入
• 协调输入
• 日期输入
• 编辑JSpinner
• 地图比例
• 数字
• ...

当输入无效时，它还允许视觉反馈，例如InputVerifier的情况不是这样。它仍然允许用户输入任何内容，但是当无效时该值根本不被接受，并且该值永远不会离开UI。我认为（但同样，这是我的观点），最好允许用户键入无效输入，只需将其自动删除，例如一个DocumentFilter。当在文本字段中输入一个字符并且没​​有出现时，我会怀疑是一个错误。

让我用一些代码（实际上是一些代码）来说明这一点。首先是小型演示应用程序。此应用程序只显示JFormattedTextField个数字。仅使用其他格式允许重用该组件以进行完全不同的验证。

import be.pcl.swing.ImprovedFormattedTextField;

import javax.swing.*;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.text.NumberFormat;

/**
 * See http://stackoverflow.com/q/1313390/1076463
 */
public class FormattedTextFieldDemo {
  public static void main( String[] args ) {
    EventQueue.invokeLater(new Runnable() {
      @Override
      public void run() {
        JFrame testFrame = new JFrame( "FormattedTextFieldDemo" );

        NumberFormat integerNumberInstance = NumberFormat.getIntegerInstance();
        ImprovedFormattedTextField integerFormattedTextField = new ImprovedFormattedTextField( integerNumberInstance, 100 );
        integerFormattedTextField.setColumns( 20 );

        testFrame.add( createButtonPanel( integerFormattedTextField ), BorderLayout.NORTH );

        final JTextArea textArea = new JTextArea(50, 50);
        PropertyChangeListener updateTextAreaListener = new PropertyChangeListener() {
          @Override
          public void propertyChange( PropertyChangeEvent evt ) {
            textArea.append( "New value: " + evt.getNewValue() + "\n" );
          }
        };
        integerFormattedTextField.addPropertyChangeListener( "value", updateTextAreaListener );

        testFrame.add( new JScrollPane( textArea ), BorderLayout.CENTER );

        testFrame.setDefaultCloseOperation( WindowConstants.DISPOSE_ON_CLOSE );
        testFrame.pack();
        testFrame.setVisible( true );
      }
    } );

  }

  private static JPanel createButtonPanel( final JFormattedTextField aTextField ){
    JPanel panel = new JPanel( new BorderLayout(  ) );
    panel.add( aTextField, BorderLayout.WEST );

    Action action = new AbstractAction() {
      {
        aTextField.addPropertyChangeListener( "editValid", new PropertyChangeListener() {
          @Override
          public void propertyChange( PropertyChangeEvent evt ) {
            setEnabled( ( ( Boolean ) evt.getNewValue() ) );
          }
        } );
        putValue( Action.NAME, "Show current value" );
      }
      @Override
      public void actionPerformed( ActionEvent e ) {
        JOptionPane.showMessageDialog( null, "The current value is [" + aTextField.getValue() + "] of class [" + aTextField.getValue().getClass() + "]" );
      }
    };
    panel.add( new JButton( action ), BorderLayout.EAST );
    return panel;
  }
}

只显示ImprovedFormattedTextField和JButton，仅在输入有效时启用（aha，吃那个DocumentFilter解决方案）。它还显示JTextArea，其中每次遇到新的有效值时都会打印该值。按下按钮显示值。

下面可以找到ImprovedFormattedTextField的代码，以及它所依赖的ParseAllFormat

package be.pcl.swing;

import javax.swing.JFormattedTextField;
import javax.swing.JTextField;
import javax.swing.KeyStroke;
import javax.swing.SwingUtilities;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import java.awt.Color;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.event.KeyEvent;
import java.text.Format;
import java.text.ParseException;

/**
 * <p>Extension of {@code JFormattedTextField} which solves some of the usability issues</p>
 */
public class ImprovedFormattedTextField extends JFormattedTextField {

  private static final Color ERROR_BACKGROUND_COLOR = new Color( 255, 215, 215 );
  private static final Color ERROR_FOREGROUND_COLOR = null;

  private Color fBackground, fForeground;

  /**
   * Create a new {@code ImprovedFormattedTextField} instance which will use {@code aFormat} for the
   * validation of the user input.
   *
   * @param aFormat The format. May not be {@code null}
   */
  public ImprovedFormattedTextField( Format aFormat ) {
    //use a ParseAllFormat as we do not want to accept user input which is partially valid
    super( new ParseAllFormat( aFormat ) );
    setFocusLostBehavior( JFormattedTextField.COMMIT_OR_REVERT );
    updateBackgroundOnEachUpdate();
    //improve the caret behavior
    //see also http://tips4java.wordpress.com/2010/02/21/formatted-text-field-tips/
    addFocusListener( new MousePositionCorrectorListener() );
  }

  /**
   * Create a new {@code ImprovedFormattedTextField} instance which will use {@code aFormat} for the
   * validation of the user input. The field will be initialized with {@code aValue}.
   *
   * @param aFormat The format. May not be {@code null}
   * @param aValue  The initial value
   */
  public ImprovedFormattedTextField( Format aFormat, Object aValue ) {
    this( aFormat );
    setValue( aValue );
  }

  private void updateBackgroundOnEachUpdate() {
    getDocument().addDocumentListener( new DocumentListener() {
      @Override
      public void insertUpdate( DocumentEvent e ) {
        updateBackground();
      }

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

      @Override
      public void changedUpdate( DocumentEvent e ) {
        updateBackground();
      }
    } );
  }

  /**
   * Update the background color depending on the valid state of the current input. This provides
   * visual feedback to the user
   */
  private void updateBackground() {
    boolean valid = validContent();
    if ( ERROR_BACKGROUND_COLOR != null ) {
      setBackground( valid ? fBackground : ERROR_BACKGROUND_COLOR );
    }
    if ( ERROR_FOREGROUND_COLOR != null ) {
      setForeground( valid ? fForeground : ERROR_FOREGROUND_COLOR );
    }
  }

  @Override
  public void updateUI() {
    super.updateUI();
    fBackground = getBackground();
    fForeground = getForeground();
  }

  private boolean validContent() {
    AbstractFormatter formatter = getFormatter();
    if ( formatter != null ) {
      try {
        formatter.stringToValue( getText() );
        return true;
      } catch ( ParseException e ) {
        return false;
      }
    }
    return true;
  }

  @Override
  public void setValue( Object value ) {
    boolean validValue = true;
    //before setting the value, parse it by using the format
    try {
      AbstractFormatter formatter = getFormatter();
      if ( formatter != null ) {
        formatter.valueToString( value );
      }
    } catch ( ParseException e ) {
      validValue = false;
      updateBackground();
    }
    //only set the value when valid
    if ( validValue ) {
      int old_caret_position = getCaretPosition();
      super.setValue( value );
      setCaretPosition( Math.min( old_caret_position, getText().length() ) );
    }
  }

  @Override
  protected boolean processKeyBinding( KeyStroke ks, KeyEvent e, int condition, boolean pressed ) {
    //do not let the formatted text field consume the enters. This allows to trigger an OK button by
    //pressing enter from within the formatted text field
    if ( validContent() ) {
      return super.processKeyBinding( ks, e,
                                      condition, pressed ) && ks != KeyStroke.getKeyStroke( KeyEvent.VK_ENTER, 0 );
    }
    else {
      return super.processKeyBinding( ks, e,
                                      condition, pressed );
    }
  }

  private static class MousePositionCorrectorListener extends FocusAdapter {
    @Override
    public void focusGained( FocusEvent e ) {
      /* After a formatted text field gains focus, it replaces its text with its
       * current value, formatted appropriately of course. It does this after
       * any focus listeners are notified. We want to make sure that the caret
       * is placed in the correct position rather than the dumb default that is
        * before the 1st character ! */
      final JTextField field = ( JTextField ) e.getSource();
      final int dot = field.getCaret().getDot();
      final int mark = field.getCaret().getMark();
      if ( field.isEnabled() && field.isEditable() ) {
        SwingUtilities.invokeLater( new Runnable() {
          @Override
          public void run() {
            // Only set the caret if the textfield hasn't got a selection on it
            if ( dot == mark ) {
              field.getCaret().setDot( dot );
            }
          }
        } );
      }
    }
  }
}

ParseAllFormat类：

package be.pcl.swing;

import java.text.AttributedCharacterIterator;
import java.text.FieldPosition;
import java.text.Format;
import java.text.ParseException;
import java.text.ParsePosition;

/**
 * <p>Decorator for a {@link Format Format} which only accepts values which can be completely parsed
 * by the delegate format. If the value can only be partially parsed, the decorator will refuse to
 * parse the value.</p>
 */
public class ParseAllFormat extends Format {
  private final Format fDelegate;

  /**
   * Decorate <code>aDelegate</code> to make sure if parser everything or nothing
   *
   * @param aDelegate The delegate format
   */
  public ParseAllFormat( Format aDelegate ) {
    fDelegate = aDelegate;
  }

  @Override
  public StringBuffer format( Object obj, StringBuffer toAppendTo, FieldPosition pos ) {
    return fDelegate.format( obj, toAppendTo, pos );
  }

  @Override
  public AttributedCharacterIterator formatToCharacterIterator( Object obj ) {
    return fDelegate.formatToCharacterIterator( obj );
  }

  @Override
  public Object parseObject( String source, ParsePosition pos ) {
    int initialIndex = pos.getIndex();
    Object result = fDelegate.parseObject( source, pos );
    if ( result != null && pos.getIndex() < source.length() ) {
      int errorIndex = pos.getIndex();
      pos.setIndex( initialIndex );
      pos.setErrorIndex( errorIndex );
      return null;
    }
    return result;
  }

  @Override
  public Object parseObject( String source ) throws ParseException {
    //no need to delegate the call, super will call the parseObject( source, pos ) method
    return super.parseObject( source );
  }
}

可能的改进：

• setBackground并未受到所有外观的尊重。有时您可以使用setForeground代替，但即使这样也不能保证所有L＆amp; Fs都能得到尊重。因此，对于视觉反馈，最好使用放置在字段旁边的感叹号。缺点是，如果您突然添加/删除图标
，这可能会弄乱布局
• 反馈仅表示输入有效/无效。没有任何东西可以表明预期的格式是什么。一种可能的解决方案是使用Format的自创扩展，其中包含有效输入的描述/示例，并将其作为工具提示放在JFormattedTextField上。

Answer 2

这个问题被引用为另一个问题的“完全重复”，此问题已被关闭。这个问题的答案非常糟糕，以至于通过链接到这个用例的更好答案，我受到启发，可以帮助那些可能在以后找到它的人。

这是answer to the closed question＆amp;可以概括为..

改为使用JSpinner。

Answer 3

import javax.swing.*;
import javax.swing.text.*;

public class JNumberTextField extends JTextField
{
    private static final char DOT = '.';
    private static final char NEGATIVE = '-';
    private static final String BLANK = "";
    private static final int DEF_PRECISION = 2;

    public static final int NUMERIC = 2;
    public static final int DECIMAL = 3;

    public static final String FM_NUMERIC = "0123456789";
    public static final String FM_DECIMAL = FM_NUMERIC + DOT;

    private int maxLength = 0;
    private int format = NUMERIC;
    private String negativeChars = BLANK;
    private String allowedChars = null;
    private boolean allowNegative = false;
    private int precision = 0;

    protected PlainDocument numberFieldFilter;

    public JNumberTextField()
    {
        this( 10, NUMERIC );
    }

    public JNumberTextField( int maxLen )
    {
        this( maxLen, NUMERIC );
    }

    public JNumberTextField( int maxLen, int format )
    {
        setAllowNegative( true );
        setMaxLength( maxLen );
        setFormat( format );

        numberFieldFilter = new JNumberFieldFilter();
        super.setDocument( numberFieldFilter );
    }

    public void setMaxLength( int maxLen )
    {
        if (maxLen > 0)
            maxLength = maxLen;
        else
            maxLength = 0;
    }

    public int getMaxLength()
    {
        return maxLength;
    }

    public void setPrecision( int precision )
    {
        if ( format == NUMERIC )
            return;

        if ( precision >= 0 )
            this.precision = precision;
        else
            this.precision = DEF_PRECISION;
    }

    public int getPrecision()
    {
        return precision;
    }

    public Number getNumber()
    {
        Number number = null;

        if ( format == NUMERIC )
            number = new Integer(getText());
        else
            number = new Double(getText());

        return number;
    }

    public void setNumber( Number value )
    {
        setText(String.valueOf(value));
    }

    public int getInt()
    {
        return Integer.parseInt( getText() );
    }

    public void setInt( int value )
    {
        setText( String.valueOf( value ) );
    }

    public float getFloat()
    {
        return ( new Float( getText() ) ).floatValue();
    }

    public void setFloat(float value)
    {
        setText( String.valueOf( value ) );
    }

    public double getDouble()
    {
        return ( new Double( getText() ) ).doubleValue();
    }

    public void setDouble(double value)
    {
        setText( String.valueOf(value) );
    }

    public int getFormat()
    {
        return format;
    }

    public void setFormat(int format)
    {
        switch ( format )
        {
        case NUMERIC:
        default:
            this.format = NUMERIC;
            this.precision = 0;
            this.allowedChars = FM_NUMERIC;
            break;

        case DECIMAL:
            this.format = DECIMAL;
            this.precision = DEF_PRECISION;
            this.allowedChars = FM_DECIMAL;
            break;
        }
    }

    public void setAllowNegative( boolean value )
    {
        allowNegative = value;

        if ( value )
            negativeChars = "" + NEGATIVE;
        else
            negativeChars = BLANK;
    }

    public boolean isAllowNegative()
    {
        return allowNegative;
    }

    public void setDocument( Document document )
    {
    }

    class JNumberFieldFilter extends PlainDocument
    {
        public JNumberFieldFilter()
        {
            super();
        }

        public void insertString(int offset, String str, AttributeSet attr) throws BadLocationException
        {
            String text = getText(0,offset) + str + getText(offset,(getLength() - offset));

            if ( str == null || text == null )
                return;

            for ( int i=0; i<str.length(); i++ )
            {
                if ( ( allowedChars + negativeChars ).indexOf( str.charAt(i) ) == -1)
                    return;
            }

            int precisionLength = 0, dotLength = 0, minusLength = 0;
            int textLength = text.length();

            try
            {
                if ( format == NUMERIC )
                {
                    if ( ! ( ( text.equals( negativeChars ) ) && ( text.length() == 1) ) )
                        new Long(text);
                }
                else if ( format == DECIMAL )
                {
                    if ( ! ( ( text.equals( negativeChars ) ) && ( text.length() == 1) ) )
                        new Double(text);

                    int dotIndex = text.indexOf(DOT);
                    if( dotIndex != -1 )
                    {
                        dotLength = 1;
                        precisionLength = textLength - dotIndex - dotLength;

                        if( precisionLength > precision )
                            return;
                    }
                }
            }
            catch(Exception ex)
            {
                return;
            }

            if ( text.startsWith( "" + NEGATIVE ) )
            {
                if ( !allowNegative )
                    return;
                else
                    minusLength = 1;
            }

            if ( maxLength < ( textLength - dotLength - precisionLength - minusLength ) )
                return;

            super.insertString( offset, str, attr );
        }
    }
}

Answer 4

虽然存在纯粹的邪恶JFormattedTextField，但仅使用Swing库并不是一种简单的方法。实现此类功能的最佳方法是使用DocumentFilter。

Some code I prepared earlier. A bit of description.

Answer 5

一种简单的方法是通过返回自定义的PlainDocument子类来继承JTextField并覆盖createDefaultModel（）。示例 - 仅限整数的文本字段：

public class NumberField extends JTextField {


@Override
protected Document createDefaultModel() {
    return new Numberdocument();
}

class Numberdocument extends PlainDocument
{
    String numbers="1234567890-";
    @Override
    public void insertString(int offs, String str, AttributeSet a)
            throws BadLocationException {
        if(!numbers.contains(str));
        else    super.insertString(offs, str, a);
    }
}

以任何方式处理insertString（）中的输入。

Answer 6

使用formatter设置文本字段的格式。

NumberFormat format = NumberFormat.getInstance();
format.setGroupingUsed(false);
NumberFormatter formatter = new NumberFormatter(format);
formatter.setValueClass(Integer.class);
formatter.setMaximum(65535);
formatter.setAllowsInvalid(false);
formatter.setCommitsOnValidEdit(true);
myTextField = new JFormattedTextField(formatter);

Answer 7

快速解决方案：

JTextField textField = new JTextField() {
  public void processKeyEvent(KeyEvent ev) {
    char c = ev.getKeyChar();
    if (c >= 48 && c <= 57) { // c = '0' ... c = '9'
      super.processKeyEvent(ev);
    }
  }
};

上述解决方案的问题是用户无法在文本字段中使用删除，左箭头，右箭头或退格键，因此我建议使用此解决方案：

this.portTextField = new JTextField() {
  public void processKeyEvent(KeyEvent ev) {
    char c = ev.getKeyChar();
    try {
      // Ignore all non-printable characters. Just check the printable ones.
      if (c > 31 && c < 127) {
        Integer.parseInt(c + "");
      }
      super.processKeyEvent(ev);
    }
    catch (NumberFormatException nfe) {
      // Do nothing. Character inputted is not a number, so ignore it.
    }
  }
};

Answer 8

另外，请考虑使用InputVerifier。

Answer 9

结合这个问题的观点数量，我发现以上解决方案都不适合我的问题。我决定制作一个自定义PlainDocument以满足我的需求。 当达到最大使用字符数或插入的文本不是整数时，此解决方案也会发出哔声。

private class FixedSizeNumberDocument extends PlainDocument
{
    private JTextComponent owner;
    private int fixedSize;

    public FixedSizeNumberDocument(JTextComponent owner, int fixedSize)
    {
        this.owner = owner;
        this.fixedSize = fixedSize;
    }

    @Override
    public void insertString(int offs, String str, AttributeSet a)
            throws BadLocationException
    {
        if (getLength() + str.length() > fixedSize) {
            str = str.substring(0, fixedSize - getLength());
            this.owner.getToolkit().beep();
        }

        try {
            Integer.parseInt(str);
        } catch (NumberFormatException e) {
            // inserted text is not a number
            this.owner.getToolkit().beep();
            return;
        }

        super.insertString(offs, str, a);
    }               
}

实现如下：

    JTextField textfield = new JTextField();
    textfield.setDocument(new FixedSizeNumberDocument(textfield,5));

Answer 10

一个非常简单的解决方案是使用动作监听器。

TextFieldActionPerformed(java.awt.event.ActionEvent evt) {
    String textFieldValue = TextField.getText();
    try {
        Integer.parseInteger(textFieldValue);
    } catch(Exception e){
        JOptionPane.showMessageDialog(null, "Please insert Valid Number Only");
        TextField.setText(textFieldValue.substring(0,textFieldValue.length()-1));
    }
}

您也可以将它用于Double：

Double.parseDouble(TextField.getText());

Answer 11

在相关JTextField的按键事件中尝试此操作。

private void JTextField(java.awt.event.KeyEvent evt) {

    // TODO add your handling code here:
    char enter = evt.getKeyChar();
    if(!(Character.isDigit(enter))){
        evt.consume();
    }
}

Answer 12

if (JTextField.getText().equals("") || !(Pattern.matches("^[0-9]+$", JTextField.getText()))) {
     JOptionPane.showMessageDialog(null, " JTextField Invalide !!!!! ");
   }

• 如果JTextField.getText（）。等于（＆＃34;＆＃34;）== - ＆gt;如果JTextField为空
• if（！（Pattern.matches（＆＃34; ^ [0-9] + $＆＃34;，JTextField.getText（））））== - ＆gt;如果 TextField包含除
之外的其他字符
• JOptionPane.showMessageDialog（null，＆＃34; JTextField Invalide !!!!! ＆＃34）; == - ＆GT;所以此消息将分发

Answer 13

Managed Executor Service

Answer 14

将此代码写入键入类型

Validation

Answer 15

请看JFormattedTextField。

Answer 16

我认为这是最好的解决方案：

JTextField textField = new JFormattedTextField(new MaskFormatter("###")); //

Answer 17

您想看看JFormattedTextField

  

格式化文本字段为开发人员提供了一种指定可在文本字段中键入的有效字符集的方法

这是JTextField的子类，因此您可以像这样使用它：

JTextField textField = new JFormattedTextField(NumberFormat.getInstance());

Answer 18

numberField = new JFormattedTextField（NumberFormat.getInstance（））;

Formatted text field tutorial

Answer 19

您可以在java中创建一个漂亮的文本字段，只接受或允许数字值。您甚至可以设置浮点值的精度...检查zybocodes中的code