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