Program: 77191
Project: 77191
Buggy source:
/** 
 * Returns the String after a given index.
 * @param part the AccessibleText.CHARACTER, AccessibleText.WORD,or AccessibleText.SENTENCE to retrieve
 * @param index an index within the text >= 0
 * @return the letter, word, or sentence, null for an invalidindex or part
 * @since 1.3
 */
public String getAfterIndex(int part,int index){
  if (index < 0 || index >= getCharCount()) {
    return null;
  }
switch (part) {
case AccessibleText.CHARACTER:
    if (index + 1 >= getCharCount()) {
      return null;
    }
  try {
    return getText(index + 1,1);
  }
 catch (  BadLocationException e) {
    return null;
  }
case AccessibleText.WORD:
try {
  String s=getText(0,getCharCount());
  BreakIterator words=BreakIterator.getWordInstance(getLocale());
  words.setText(s);
  int start=words.following(index);
  if (start == BreakIterator.DONE || start >= s.length()) {
    return null;
  }
  int end=words.following(start);
  if (end == BreakIterator.DONE || end >= s.length()) {
    return null;
  }
  return s.substring(start,end);
}
 catch (BadLocationException e) {
  return null;
}
case AccessibleText.SENTENCE:
try {
String s=getText(0,getCharCount());
BreakIterator sentence=BreakIterator.getSentenceInstance(getLocale());
sentence.setText(s);
int start=sentence.following(index);
if (start == BreakIterator.DONE || start > s.length()) {
  return null;
}
int end=sentence.following(start);
if (end == BreakIterator.DONE || end > s.length()) {
  return null;
}
return s.substring(start,end);
}
 catch (BadLocationException e) {
return null;
}
default :
return null;
}
}

Fixed version (ground truth):
/** 
 * Returns the String after a given index.
 * @param part the AccessibleText.CHARACTER, AccessibleText.WORD,or AccessibleText.SENTENCE to retrieve
 * @param index an index within the text &gt;= 0
 * @return the letter, word, or sentence, null for an invalidindex or part
 * @since 1.3
 */
public String getAfterIndex(int part,int index){
  if (index < 0 || index >= getCharCount()) {
    return null;
  }
switch (part) {
case AccessibleText.CHARACTER:
    if (index + 1 >= getCharCount()) {
      return null;
    }
  try {
    return getText(index + 1,1);
  }
 catch (  BadLocationException e) {
    return null;
  }
case AccessibleText.WORD:
try {
  String s=getText(0,getCharCount());
  BreakIterator words=BreakIterator.getWordInstance(getLocale());
  words.setText(s);
  int start=words.following(index);
  if (start == BreakIterator.DONE || start >= s.length()) {
    return null;
  }
  int end=words.following(start);
  if (end == BreakIterator.DONE || end >= s.length()) {
    return null;
  }
  return s.substring(start,end);
}
 catch (BadLocationException e) {
  return null;
}
case AccessibleText.SENTENCE:
try {
String s=getText(0,getCharCount());
BreakIterator sentence=BreakIterator.getSentenceInstance(getLocale());
sentence.setText(s);
int start=sentence.following(index);
if (start == BreakIterator.DONE || start > s.length()) {
  return null;
}
int end=sentence.following(start);
if (end == BreakIterator.DONE || end > s.length()) {
  return null;
}
return s.substring(start,end);
}
 catch (BadLocationException e) {
return null;
}
default :
return null;
}
}