output: #fixed code
                                  public static void buildSysGenProfilingFile() {
          long startMills = System.currentTimeMillis();
          String filePath = ProfilingConfig.getInstance().getSysProfilingParamsFile();
          String tempFilePath = filePath + "_tmp";
          File tempFile = new File(tempFilePath);
          try (BufferedWriter fileWriter = new BufferedWriter(new FileWriter(tempFile, false), 8 * 1024)) {
              fileWriter.write("#This is a file automatically generated by MyPerf4J, please do not edit!\n");
  
              MethodTagMaintainer tagMaintainer = MethodTagMaintainer.getInstance();
              Map<Integer, MethodMetricsInfo> methodMap = MethodMetricsHistogram.methodMap;
              for (Map.Entry<Integer, MethodMetricsInfo> entry : methodMap.entrySet()) {
                  Integer methodId = entry.getKey();
                  MethodMetricsInfo info = entry.getValue();
                  if (info.getCount() <= 0) {
                      continue;
                  }
  
                  MethodTag methodTag = tagMaintainer.getMethodTag(methodId);
                  fileWriter.write(methodTag.getFullDesc());
                  fileWriter.write('=');
  
                  int mostTimeThreshold = calMostTimeThreshold(info);
                  fileWriter.write(mostTimeThreshold + ":" + calOutThresholdCount(mostTimeThreshold));
                  fileWriter.newLine();
              }
              fileWriter.flush();
  
              File destFile = new File(filePath);
              boolean rename = tempFile.renameTo(destFile) && destFile.setReadOnly();
              Logger.debug("MethodMetricsHistogram.buildSysGenProfilingFile(): rename " + tempFile.getName() + " to " + destFile.getName() + " " + (rename ? "success" : "fail"));
          } catch (Exception e) {
              Logger.error("MethodMetricsHistogram.buildSysGenProfilingFile()", e);
          } finally {
              Logger.debug("MethodMetricsHistogram.buildSysGenProfilingFile() finished, cost=" + (System.currentTimeMillis() - startMills) + "ms");
          }
      }
input: #vulnerable code 
                                  public static void buildSysGenProfilingFile() {
          long startMills = System.currentTimeMillis();
          String filePath = ProfilingConfig.getInstance().getSysProfilingParamsFile();
          String tempFilePath = filePath + "_tmp";
          File tempFile = new File(tempFilePath);
          try (BufferedWriter fileWriter = new BufferedWriter(new FileWriter(tempFile, false), 8 * 1024)) {
              fileWriter.write("#This is a file automatically generated by MyPerf4J, please do not edit!\n");
  
              MethodTagMaintainer tagMaintainer = MethodTagMaintainer.getInstance();
              Map<Integer, MethodMetricsInfo> methodMap = MethodMetricsHistogram.methodMap;
              for (Map.Entry<Integer, MethodMetricsInfo> entry : methodMap.entrySet()) {
                  Integer methodId = entry.getKey();
                  MethodMetricsInfo info = entry.getValue();
                  if (info.getCount() <= 0) {
                      continue;
                  }
  
                  MethodTag methodTag = tagMaintainer.getMethodTag(methodId);
                  fileWriter.write(methodTag.getFullDesc());
                  fileWriter.write('=');
  
                  int mostTimeThreshold = calMostTimeThreshold(info);
                  fileWriter.write(mostTimeThreshold + ":" + calOutThresholdCount(mostTimeThreshold));
                  fileWriter.newLine();
              }
              fileWriter.flush();
  
              File destFile = new File(filePath);
              boolean rename = tempFile.renameTo(destFile);
              Logger.debug("MethodMetricsHistogram.buildSysGenProfilingFile(): rename " + tempFile.getName() + " to " + destFile.getName() + " " + (rename ? "success" : "fail"));
          } catch (Exception e) {
              Logger.error("MethodMetricsHistogram.buildSysGenProfilingFile()", e);
          } finally {
              Logger.debug("MethodMetricsHistogram.buildSysGenProfilingFile() finished, cost=" + (System.currentTimeMillis() - startMills) + "ms");
          }
      } 
                              #location 19 
                              #vulnerability type NULL_DEREFERENCE