Problems creating my own JTextField

Question

i'm trying to write my own textfield that will get a string of the following format: 1-4 digits, "/", 2 digits.
so I wrote a new class, but it doesn't work at all.
help, please.
package union.General;
import javax.swing.*;
import javax.swing.text.*;
import union.Entities.UnionCase.*;
public class JOfficeCaseIdField
extends JTextField {
public JOfficeCaseIdField() {
setText(" / ");
protected Document createDefaultModel() {
return new JOfficeCaseIdDocument();
protected class JOfficeCaseIdDocument extends PlainDocument {
public void insertString(int offs, String str, AttributeSet a) throws
BadLocationException {
char[] source = str.toCharArray();
char[] result = new char[7];
int j = 0;
for (j=0; j<result.length; j++) {
result[j] = ' ';
j=0;
for (int i = 0; i < source.length && j<result.length; i++) {
if (offs + j == 4) {
j++;
if (Character.isDigit(source))
result[j++] = source[i];
else {
//invalid character '/' is done by this document and the user should only enter digits
result[4] = '/';
super.insertString(offs, new String(result, 0, j), a);

Answer 1

how bout this, why doesn't this work well?
static final private int DASH_PLACE_FROM_END = 3;
static final private int MAX_STRING = 7;
static final private char DASH_CHAR = '/';
static final private String DASH_STRING = new String(new char[] {DASH_CHAR}); //the string "/"
protected class JOfficeCaseIdDocument extends PlainDocument {
public void insertString(int offs, String str, AttributeSet a) throws
BadLocationException {
char[] source = str.toCharArray();
char[] target = new char[str.length()];
int finalLength = 0;
for (int i=0; i<source.length; i++) {
if (Character.isDigit(source)) {
target[finalLength++] = source[i];
String mainString = new String(target,0,finalLength);
String oldText = getText(0,getLength());
String newInsertString;
this.remove(0,getLength());
newInsertString = oldText;
String firstString = "";
String lastString = "";
if (offs > 0 ) {
firstString = newInsertString.substring(0,offs);
if (offs<newInsertString.length()) {
lastString = newInsertString.substring(offs,newInsertString.length());
newInsertString =
firstString +
mainString +
lastString;
newInsertString.replaceAll(DASH_STRING,"");
if (newInsertString.length() >= DASH_PLACE_FROM_END) {
newInsertString =
newInsertString.substring(0,newInsertString.length()-DASH_PLACE_FROM_END) +
DASH_STRING +
newInsertString.substring(newInsertString.length()-DASH_PLACE_FROM_END+1,
newInsertString.length()-1);
super.insertString(0, newInsertString, a);