output: #fixed code
                               public void run() {
  		logger.info("ProactiveGcTask starting, oldGenOccupancyFraction:" + oldGenOccupancyFraction);
  		try {
  			long usedOldBytes = logOldGenStatus();
  
  			if (needTriggerGc(maxOldBytes, usedOldBytes, oldGenOccupancyFraction)) {
  				preGc();
  				doGc();
  				postGc();
  			}
  		} catch (Exception e) {
  			logger.error(e.getMessage(), e);
  		} finally {
  			scheduler.reschedule(this);
  		}
  	}
input: #vulnerable code 
                               public void run() {
  		log.info("ProactiveGcTask starting, oldGenOccupancyFraction:" + oldGenOccupancyFraction + ", datetime: "
  				+ new Date());
  		try {
  			oldMemoryPool = getOldMemoryPool();
  			long maxOldBytes = getMemoryPoolMaxOrCommitted(oldMemoryPool);
  			long oldUsedBytes = oldMemoryPool.getUsage().getUsed();
  			log.info(String.format("max old gen: %.2f MB, used old gen: %.2f MB, available old gen: %.2f MB.",
  					SizeUnit.BYTES.toMegaBytes(maxOldBytes), SizeUnit.BYTES.toMegaBytes(oldUsedBytes),
  					SizeUnit.BYTES.toMegaBytes(maxOldBytes - oldUsedBytes)));
  			if (needTriggerGc(maxOldBytes, oldUsedBytes, oldGenOccupancyFraction)) {
  				preGc();
  				doGc();
  				postGc();
  			}
  		} catch (Exception e) {
  			log.error(e.getMessage(), e);
  		} finally {
  			if (!scheduler.isShutdown()) { // reschedule this task
  				try {
  					scheduler.reschedule(this);
  				} catch (Exception e) {
  					log.error(e.getMessage(), e);
  				}
  			}
  		}
  	} 
                              #location 6 
                              #vulnerability type NULL_DEREFERENCE