Program: 184580
Project: 184580
Buggy source:
public synchronized IImage getImageAt(int index){
  if (index < 0 || index > getCount()) {
    throw new IndexOutOfBoundsException("String_Node_Str" + index + "String_Node_Str"+ getCount());
  }
  if (mSkipCounts == null || mSubList.length > mSkipCounts.length) {
    mSkipCounts=new int[mSubList.length];
  }
  if (mSkipList == null) {
    mSkipList=new ArrayList<Long>();
  }
  for (int i=0; i < mSubList.length; i++) {
    mSkipCounts[i]=0;
  }
  int skipCount=0;
  for (int i=0; i < mSkipList.size(); i++) {
    long v=mSkipList.get(i);
    int offset=(int)(v & 0xFFFFFFFF);
    int which=(int)(v >> 32);
    if (skipCount + offset > index) {
      int subindex=mSkipCounts[which] + (index - skipCount);
      IImage img=mSubList[which].getImageAt(subindex);
      return img;
    }
    skipCount+=offset;
    mSkipCounts[which]+=offset;
  }
  while (true) {
    long maxTimestamp=mSort == ImageManager.SORT_ASCENDING ? Long.MAX_VALUE : Long.MIN_VALUE;
    int which=-1;
    for (int i=0; i < mSubList.length; i++) {
      int pos=mSkipCounts[i];
      IImageList list=mSubList[i];
      if (pos < list.getCount()) {
        IImage image=list.getImageAt(pos);
        if (image != null) {
          long timestamp=image.getDateTaken();
          if (mSort == ImageManager.SORT_ASCENDING ? (timestamp < maxTimestamp) : (timestamp > maxTimestamp)) {
            maxTimestamp=timestamp;
            which=i;
          }
        }
      }
    }
    if (which == -1) {
      return null;
    }
    boolean done=false;
    if (mSkipList.size() > 0) {
      int pos=mSkipList.size() - 1;
      long oldEntry=mSkipList.get(pos);
      if ((oldEntry >> 32) == which) {
        long newEntry=oldEntry + 1;
        mSkipList.set(pos,newEntry);
        done=true;
      }
    }
    if (!done) {
      long newEntry=((long)which << 32) | 1;
      mSkipList.add(newEntry);
    }
    if (skipCount++ == index) {
      return mSubList[which].getImageAt(mSkipCounts[which]);
    }
    mSkipCounts[which]+=1;
  }
}

Fixed version (ground truth):
public IImage getImageAt(int index){
  if (index < 0 || index > getCount()) {
    throw new IndexOutOfBoundsException("String_Node_Str" + index + "String_Node_Str"+ getCount());
  }
  if (mSkipCounts == null || mSubList.length > mSkipCounts.length) {
    mSkipCounts=new int[mSubList.length];
  }
  if (mSkipList == null) {
    mSkipList=new ArrayList<Long>();
  }
  for (int i=0; i < mSubList.length; i++) {
    mSkipCounts[i]=0;
  }
  int skipCount=0;
  for (int i=0; i < mSkipList.size(); i++) {
    long v=mSkipList.get(i);
    int offset=(int)(v & 0xFFFFFFFF);
    int which=(int)(v >> 32);
    if (skipCount + offset > index) {
      int subindex=mSkipCounts[which] + (index - skipCount);
      IImage img=mSubList[which].getImageAt(subindex);
      return img;
    }
    skipCount+=offset;
    mSkipCounts[which]+=offset;
  }
  while (true) {
    long maxTimestamp=mSort == ImageManager.SORT_ASCENDING ? Long.MAX_VALUE : Long.MIN_VALUE;
    int which=-1;
    for (int i=0; i < mSubList.length; i++) {
      int pos=mSkipCounts[i];
      IImageList list=mSubList[i];
      if (pos < list.getCount()) {
        IImage image=list.getImageAt(pos);
        if (image != null) {
          long timestamp=image.getDateTaken();
          if (mSort == ImageManager.SORT_ASCENDING ? (timestamp < maxTimestamp) : (timestamp > maxTimestamp)) {
            maxTimestamp=timestamp;
            which=i;
          }
        }
      }
    }
    if (which == -1) {
      return null;
    }
    boolean done=false;
    if (mSkipList.size() > 0) {
      int pos=mSkipList.size() - 1;
      long oldEntry=mSkipList.get(pos);
      if ((oldEntry >> 32) == which) {
        long newEntry=oldEntry + 1;
        mSkipList.set(pos,newEntry);
        done=true;
      }
    }
    if (!done) {
      long newEntry=((long)which << 32) | 1;
      mSkipList.add(newEntry);
    }
    if (skipCount++ == index) {
      return mSubList[which].getImageAt(mSkipCounts[which]);
    }
    mSkipCounts[which]+=1;
  }
}