JTextField只接受有效的未签名短裤吗? (使用KeyAdapter) [英] JTextField accept only valid unsigned Shorts? (Using KeyAdapter)
问题描述
下面是我试图使KeyAdapter只接受小于65535的值的KeyAdapter.似乎它在实际位置后面落后了一个按键.例如，如果我键入"55"，则System.out.println将产生"5"，执行"3298"将产生"329"，等等.
Below is the KeyAdapter I tried to get working to only accept values less than 65535. It seems as though it gets it one keystroke behind where it actually should. For example, If I type "55", the System.out.println will yield "5", doing "3298" will yield "329", etc.
// Allows for unsigned short values only
KeyAdapter unsignedShortAdapter = new KeyAdapter() {
public void keyTyped(KeyEvent e) {
char c = e.getKeyChar();
int tempInt = 0;
JTextField temp = null;
if (!((Character.isDigit(c) || (c == KeyEvent.VK_BACK_SPACE) || (c == KeyEvent.VK_DELETE)))) {
getToolkit().beep();
e.consume();
}
try {
temp = (JTextField) e.getSource();
System.out.println(temp.getText());
tempInt = (Integer.parseInt(temp.getText().toString()));
} catch (NumberFormatException e1) {
} finally {
if (tempInt > (Short.MAX_VALUE * 2)) {
getToolkit().beep();
e.consume();
temp.setText(temp.getText().substring(0, temp.getText().length() - 1));
invalidate();
}
}
}
};
推荐答案
因此，不是您发现的KeyListener，它是不可靠的，并且会引起很多讨厌的副作用(以及可能的文档突变例外:P )，我们应该使用DocumentFilter，因为这正是它的设计目的
So, instead of a KeyListener, which you've found, is unreliable and will cause lots of nasty side effects (and possible Document Mutation exceptions :P), we should use a DocumentFilter, cause that's what it's designed for
public class ShortFilter extends DocumentFilter {
protected boolean valid(String text) {
boolean valid = true;
for (char check : text.toCharArray()) {
if (!Character.isDigit(check)) {
valid = false;
break;
}
}
if (valid) {
int iValue = Integer.parseInt(text);
valid = iValue <= (Short.MAX_VALUE * 2);
}
return valid;
}
@Override
public void insertString(FilterBypass fb, int offset, String text, AttributeSet attr) throws BadLocationException {
StringBuilder sb = new StringBuilder(fb.getDocument().getText(0, fb.getDocument().getLength()));
sb.insert(offset, text);
if (valid(sb.toString())) {
super.insertString(fb, offset, text, attr);
}
}
@Override
public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException {
if (length > 0) {
StringBuilder sb = new StringBuilder(fb.getDocument().getText(0, fb.getDocument().getLength()));
sb.delete(offset, length);
sb.insert(offset, text);
if (valid(sb.toString())) {
super.replace(fb, offset, length, text, attrs);
}
} else {
insertString(fb, offset, text, attrs);
}
}
}
您需要将其应用于字段的文档
You will need to apply this to the field's document
((AbstractDocument) field.getDocument()).setDocumentFilter(new ShortFilter());
我要结帐
- http://www.jroller.com/dpmihai/entry/documentfilter
- http://docs.oracle. com/javase/7/docs/api/javax/swing/text/DocumentFilter.html
- http://www.jroller.com/dpmihai/entry/documentfilter
- http://docs.oracle.com/javase/7/docs/api/javax/swing/text/DocumentFilter.html
更多信息
十进制包含的更新
基本上，如果要允许包含小数，则需要在valid方法中允许使用该字符.
Basically, if you want to allow the inclusion of a decimal, you need to allow for the character in the valid method.
您还需要检查当前文档的内容
You also need to check the current document's contents
StringBuilder sb = new StringBuilder(fb.getDocument().getText(0, fb.getDocument().getLength()));
// Update the StringBuilder as per noraml
// Check valid as per normal
if (text.contains(".") && sb.contains(".")) {
// already have decimal place
} else {
// Business as usual...
}
这篇关于JTextField只接受有效的未签名短裤吗? (使用KeyAdapter)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
