使JSpinner只读取数字但也可以检测退格

• 您

  JFormattedTextField

  正确的实现不正确

  JSpinner

  ，您有实现

  documentFilter

  用于过滤从keyboad

  Chars

  输入或从ClipBoard粘贴的un_wanted的工具，（感谢@StanislavL）

• 你有自己的问题与解决

  selectAll()

  上

  focusGained()

  包裹成

  invokeLater()

  ，

例

import java.awt.BorderLayout;import javax.swing.JButton;import javax.swing.Jframe;import javax.swing.JSpinner;import javax.swing.SpinnerNumberModel;import javax.swing.SwingUtilities;import javax.swing.text.*;public class TestDigitsonlySpinner {    public static void main(String... args) {        SwingUtilities.invokeLater((Runnable) new Runnable() { @Override public void run() {     Jframe frame = new Jframe("enter digit");     frame.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE);     JSpinner jspinner = makeDigitsonlySpinnerUsingdocumentFilter();     frame.getContentPane().add(jspinner, BorderLayout.CENTER);     frame.getContentPane().add(new JButton("just another widget"), BorderLayout.SOUTH);     frame.pack();     frame.setVisible(true); } private JSpinner makeDigitsOnlySpinner_BasicAttempt() {     JSpinner spinner = new JSpinner(new SpinnerNumberModel());     return spinner; } private JSpinner makeDigitsonlySpinnerUsingdocumentFilter() {     JSpinner spinner = new JSpinner(new SpinnerNumberModel(0, 0, 20, 1));     JSpinner.NumberEditor jsEditor = (JSpinner.NumberEditor) spinner.getEditor();     final document jsDoc = jsEditor.getTextField().getdocument();     if (jsDoc instanceof Plaindocument) {         Abstractdocument doc = new Plaindocument() {  private static final long serialVersionUID = 1L;  @Override  public void setdocumentFilter(documentFilter filter) {      if (filter instanceof MydocumentFilter) {          super.setdocumentFilter(filter);      }  }         };         doc.setdocumentFilter(new MydocumentFilter());         jsEditor.getTextField().setdocument(doc);     }     return spinner; }        });    }    private static class MydocumentFilter extends documentFilter {        @Override        public void insertString(FilterBypass fb, int offset, String string, AttributeSet attr) throws BadLocationException { if (stringContainsOnlyDigits(string)) {     super.insertString(fb, offset, string, attr); }        }        @Override        public void remove(FilterBypass fb, int offset, int length) throws BadLocationException { super.remove(fb, offset, length);        }        @Override        public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException { if (stringContainsOnlyDigits(text)) {     super.replace(fb, offset, length, text, attrs); }        }        private boolean stringContainsOnlyDigits(String text) { for (int i = 0; i < text.length(); i++) {     if (!Character.isDigit(text.charAt(i))) {         return false;     } } return true;        }    }    private TestDigitsonlySpinner() {    }}