Program: 49979
Project: 49979
Buggy source:
@Override public void actionPerformed(ActionEvent arg0){
  int numObjectives=0;
  if (!whiteRules.getObjectiveName().equals("String_Node_Str")) {
    for (    Piece p : whiteTeam) {
      if (p.getName().equals(whiteRules.getObjectiveName()))       numObjectives++;
    }
    if (numObjectives != 1) {
      JOptionPane.showMessageDialog(null,"String_Node_Str");
      return;
    }
  }
  numObjectives=0;
  if (!blackRules.getObjectiveName().equals("String_Node_Str")) {
    for (    Piece p : blackTeam) {
      if (p.getName().equals(blackRules.getObjectiveName()))       numObjectives++;
    }
    if (numObjectives != 1) {
      JOptionPane.showMessageDialog(null,"String_Node_Str");
      return;
    }
  }
  b.whiteTeam=whiteTeam;
  boolean set=false;
  for (  Piece p : whiteTeam) {
    if (p.getName().equals("String_Node_Str")) {
      whiteRules.setObjectivePiece(new ObjectivePiece("String_Node_Str","String_Node_Str"));
      set=true;
      break;
    }
  }
  if (!set) {
    whiteRules.setObjectivePiece(new ObjectivePiece("String_Node_Str","String_Node_Str"));
  }
  b.blackTeam=blackTeam;
  set=false;
  for (  Piece p : blackTeam) {
    if (p.getName().equals("String_Node_Str")) {
      blackRules.setObjectivePiece(new ObjectivePiece("String_Node_Str","String_Node_Str"));
      set=true;
      break;
    }
  }
  if (!set) {
    blackRules.setObjectivePiece(new ObjectivePiece("String_Node_Str","String_Node_Str"));
  }
  b.writeFile(whiteRules,blackRules);
  Driver.getInstance().revertPanel();
}

Fixed version (ground truth):
@Override public void actionPerformed(ActionEvent arg0){
  System.out.println("String_Node_Str");
  for (  Piece p : whiteTeam) {
    System.out.print(p.getName() + "String_Node_Str");
  }
  System.out.println("String_Node_Str");
  for (  Piece p : blackTeam) {
    System.out.print(p.getName() + "String_Node_Str");
  }
  int numObjectives=0;
  if (!whiteRules.getObjectiveName().equals("String_Node_Str")) {
    for (    Piece p : whiteTeam) {
      if (p.getName().equals(whiteRules.getObjectiveName()))       numObjectives++;
    }
    if (numObjectives != 1) {
      JOptionPane.showMessageDialog(null,"String_Node_Str");
      return;
    }
  }
  numObjectives=0;
  if (!blackRules.getObjectiveName().equals("String_Node_Str")) {
    for (    Piece p : blackTeam) {
      if (p.getName().equals(blackRules.getObjectiveName()))       numObjectives++;
    }
    if (numObjectives != 1) {
      JOptionPane.showMessageDialog(null,"String_Node_Str");
      return;
    }
  }
  b.whiteTeam=whiteTeam;
  boolean set=false;
  for (  Piece p : whiteTeam) {
    if (p.getName().equals("String_Node_Str")) {
      whiteRules.setObjectivePiece(new ObjectivePiece("String_Node_Str","String_Node_Str"));
      set=true;
      break;
    }
  }
  if (!set) {
    whiteRules.setObjectivePiece(new ObjectivePiece("String_Node_Str","String_Node_Str"));
  }
  b.blackTeam=blackTeam;
  set=false;
  for (  Piece p : blackTeam) {
    if (p.getName().equals("String_Node_Str")) {
      blackRules.setObjectivePiece(new ObjectivePiece("String_Node_Str","String_Node_Str"));
      set=true;
      break;
    }
  }
  if (!set) {
    blackRules.setObjectivePiece(new ObjectivePiece("String_Node_Str","String_Node_Str"));
  }
  b.writeFile(whiteRules,blackRules);
  Driver.getInstance().revertPanel();
}