JTextField限制 输入数字

貌似有很多方法，先记了再说...

1.限制输入数字

用法 textfield.setDocument(new IntegerDocument());

class IntegerDocument
extends PlainDocument

{

public void
insertString(int offset, String s, 
AttributeSet
attributeSet) throws BadLocationException

{

try

{

Integer.parseInt(s);

}

catch(Exception
ex)

{

Toolkit.getDefaultToolkit().beep();

return;

}

super.insertString(offset, s,
attributeSet);

}

}

2.限制输入数字和长度

public class NumberLenghtLimitedDmt extends PlainDocument
{

   private int
limit; 
   public NumberLenghtLimitedDmt(int
limit)
{
    super();
       this.limit
=
limit;
    } 
   public
void insertString
     (int offset, String str,
AttributeSet
attr)
                                   throws
BadLocationException
{   
       if
(str ==
null){
        return;
       }
       if
((getLength() + str.length()) <= limit)
{
     
       char[]
upper = str.toCharArray();
       int
length=0;
       for (int i = 0; i <
upper.length; i++)
{     
           if
(upper[i]>=‘0‘&&upper[i]<=‘9‘){         
              upper[length++]
=
upper[i];
           }
       }
         super.insertString(offset,
new String(upper,0,length),
attr);
      }
    }
}

用法:

JTextField   text=new JTextField();

text.setDocument(new NumberLenghtLimitedDmt(7));

那么这个文本框只能输入7位而且是只能是数字!!!

3.添加KeyListener

public void
keyTyped(KeyEvent
e)
    {
     if
((e.getKeyChar() >= e.VK_0 && e.getKeyChar() <=
e.VK_9) 
      ||
e.getKeyChar() == e.VK_ENTER || e.getKeyChar() ==
e.VK_TAB
      || e.getKeyChar() ==
e.VK_BACK_SPACE || e.getKeyChar() ==
e.VK_DELETE 
      ||
e.getKeyChar