void (InstructionImpl instruction) { final InstructionImpl popped = myProcessingStack.pop(); if (!instruction.equals(popped)) { String description = "popped : " + popped.toString() + " : " + popped.hashCode() + ", " + popped.getClass() + "\n" + "expected: " + instruction.toString() + " : " + instruction.hashCode() + ", " + instruction.getClass() + "\n" + "same objects: " + (popped == instruction) + "\n"; error(description); } }