Program: 70801
Project: 70801
Buggy source:
/** 
 * Updates the format Pattern String, and Preview.
 */
private void updatePreview(){
  markDirty(hasLoaded);
  String gText;
  if (getPreviewText() == null) {
    gText=DEFAULT_PREVIEW_TEXT;
  }
 else {
    gText=getPreviewText();
  }
  String category=provider.getCategory4DisplayName(typeChoicer.getText());
  setCategory(category);
  if (provider.STRING_FORMAT_TYPE_UNFORMATTED.equals(category)) {
    String pattern=null;
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(gText);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(null);
  }
 else   if (provider.STRING_FORMAT_TYPE_UPPERCASE.equals(category)) {
    String pattern=FormatStringPattern.getPatternForCategory(category);
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(gText);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
 else   if (provider.STRING_FORMAT_TYPE_LOWERCASE.equals(category)) {
    String pattern=FormatStringPattern.getPatternForCategory(category);
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(gText);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
 else   if (provider.STRING_FORMAT_TYPE_ZIP_CODE.equals(category)) {
    String pattern=FormatStringPattern.getPatternForCategory(category);
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(SAMPLE_TEXT_ZIP_CODE);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
 else   if (provider.STRING_FORMAT_TYPE_ZIP_CODE_4.equals(category)) {
    String pattern=FormatStringPattern.getPatternForCategory(category);
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(SAMPLE_TEXT_ZIP_C0DE4);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
 else   if (provider.STRING_FORMAT_TYPE_PHONE_NUMBER.equals(category)) {
    String pattern=FormatStringPattern.getPatternForCategory(category);
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(SAMPLE_TEXT_PHONE_NUMBER);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
 else   if (provider.STRING_FORMAT_TYPE_SOCIAL_SECURITY_NUMBER.equals(category)) {
    String pattern=FormatStringPattern.getPatternForCategory(category);
    gText=SAMPLE_TEXT_SOCIAL_SECURITY_NUMBER;
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(SAMPLE_TEXT_SOCIAL_SECURITY_NUMBER);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
 else   if (provider.STRING_FORMAT_TYPE_CUSTOM.equals(category)) {
    String pattern=formatCode.getText();
    String fmtStr;
    if (provider.isBlank(previewTextBox.getText())) {
      fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(gText);
    }
 else {
      fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(previewTextBox.getText());
    }
    cPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
  return;
}

Fixed version (ground truth):
/** 
 * Updates the format Pattern String, and Preview.
 */
private void updatePreview(){
  markDirty(hasLoaded);
  String gText;
  if (getPreviewText() == null) {
    gText=DEFAULT_PREVIEW_TEXT;
  }
 else {
    gText=getPreviewText();
  }
  String category=provider.getCategory4DisplayName(typeChoicer.getText());
  setCategory(category);
  if (provider.STRING_FORMAT_TYPE_UNFORMATTED.equals(category)) {
    String pattern=null;
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(gText);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(null);
  }
 else   if (provider.STRING_FORMAT_TYPE_UPPERCASE.equals(category)) {
    String pattern=FormatStringPattern.getPatternForCategory(category);
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(gText);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
 else   if (provider.STRING_FORMAT_TYPE_LOWERCASE.equals(category)) {
    String pattern=FormatStringPattern.getPatternForCategory(category);
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(gText);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
 else   if (provider.STRING_FORMAT_TYPE_ZIP_CODE.equals(category)) {
    String pattern=FormatStringPattern.getPatternForCategory(category);
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(SAMPLE_TEXT_ZIP_CODE);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
 else   if (provider.STRING_FORMAT_TYPE_ZIP_CODE_4.equals(category)) {
    String pattern=FormatStringPattern.getPatternForCategory(category);
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(SAMPLE_TEXT_ZIP_C0DE4);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
 else   if (provider.STRING_FORMAT_TYPE_PHONE_NUMBER.equals(category)) {
    String pattern=FormatStringPattern.getPatternForCategory(category);
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(SAMPLE_TEXT_PHONE_NUMBER);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
 else   if (provider.STRING_FORMAT_TYPE_SOCIAL_SECURITY_NUMBER.equals(category)) {
    String pattern=FormatStringPattern.getPatternForCategory(category);
    String fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(SAMPLE_TEXT_SOCIAL_SECURITY_NUMBER);
    generalPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
 else   if (provider.STRING_FORMAT_TYPE_CUSTOM.equals(category)) {
    String pattern=formatCode.getText();
    String fmtStr;
    if (provider.isBlank(previewTextBox.getText())) {
      fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(gText);
    }
 else {
      fmtStr=new StringFormatter(pattern,DEFAULT_LOCALE).format(previewTextBox.getText());
    }
    cPreviewLabel.setText(validatedFmtStr(fmtStr));
    setPattern(pattern);
  }
  return;
}