CODEWITHSUNDEEP
java
exussum
exussum

Reputation: 18550

Java loop not looping when code is added to loop

Im confused as when i add code inside a loop it stops the looping (effectivly ending after the first round).

Code which is working fine

StringBuilder sb = new StringBuilder(4096);
  while ((rs.next())) {
  System.err.println(rs.getRow());
  sb.append(rs.getString(1)).append(",");
  }
writeToCell(sheet,"P",row.getRowNum()+1,sb.toString());

Code which doesnt loop

StringBuilder sb = new StringBuilder(4096);
    while ((rs.next())) {
    System.err.println(rs.getRow());
    String p=rs.getString(1);
    ArrayList<Parent> pscore = new ArrayList();
    pscore.add(new Parent(p));
    String Score= getSegment(pscore);
    sb.append(p).append("(").append(Score).append("),");
    }
writeToCell(sheet,"P",row.getRowNum()+1,sb.toString());

I cant figure out why it would loop in the top version and not the bottom version. No errors are thrown

Upvotes: 0

Views: 118

Answers (2)

Peter Lawrey
Peter Lawrey

Reputation: 533442

My guess is that

pscore.add(new Parent(p));
String Score= getSegment(pscore);

performs a database query which replaces the rs which has finished before getSegment returns so the next call to rs.next() will be false.

To avoid this I would make sure that rs is a local variable instead of a field.

If this is the case, the best solution is likely to make the original SELECT a join between the tables so that is has all the information you need rather than performing a query per row.

Upvotes: 1

exussum
exussum

Reputation: 18550

Keppils comment drew me towards the answer

"Maybe something happens to rs in the getSegment() method? "

Im not sure how to give any credit ive upvoted the comment but cant accept the comment as correct

The Parent Class uses a static variable for the database connection so when its defined it overridden the rs variable.

Upvotes: 0

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