怎么限制JTextField的输入长度
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*/ package components;/* A 1.4 class used by TextComponentDemo.java. */import javax.swing.*;
import javax.swing.text.*;
import java.awt.Toolkit;public class DocumentSizeFilter extends DocumentFilter {
int maxCharacters;
boolean DEBUG = false; public DocumentSizeFilter(int maxChars) {
maxCharacters = maxChars;
} public void insertString(FilterBypass fb, int offs,
String str, AttributeSet a)
throws BadLocationException {
if (DEBUG) {
System.out.println("in DocumentSizeFilter's insertString method");
} //This rejects the entire insertion if it would make
//the contents too long. Another option would be
//to truncate the inserted string so the contents
//would be exactly maxCharacters in length.
if ((fb.getDocument().getLength() + str.length()) <= maxCharacters)
super.insertString(fb, offs, str, a);
else
Toolkit.getDefaultToolkit().beep();
}
public void replace(FilterBypass fb, int offs,
int length,
String str, AttributeSet a)
throws BadLocationException {
if (DEBUG) {
System.out.println("in DocumentSizeFilter's replace method");
}
//This rejects the entire replacement if it would make
//the contents too long. Another option would be
//to truncate the replacement string so the contents
//would be exactly maxCharacters in length.
if ((fb.getDocument().getLength() + str.length()
- length) <= maxCharacters)
super.replace(fb, offs, length, str, a);
else
Toolkit.getDefaultToolkit().beep();
}}