jtextfield1.java

学生管理系统

package guanlixitong;

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

public class JTextField1
    extends JTextField {
  public JTextField1() {

  }

  protected Document createDefaultModel() {
    return new DocumentNO();
  }

  private class DocumentNO
      extends PlainDocument {
    public void insertString(int offs, String str, AttributeSet a) throws
        BadLocationException {
      if (str == null) {
        return;
      }
      char[] upper = str.toCharArray();
      int length = 0;
      for (int i = 0; i < upper.length; i++) {
        if ((upper[i] >= '0' && upper[i] <= '9')||upper[i]=='.') {
          upper[length++] = upper[i];
        }
      }
      super.insertString(offs, new String(upper, 0, length), a);
    }
  }

}