output: #fixed code
                                  private void populateMarkovMatrix(String markovMatrixStorageLocation) {
  
          File file = new File(markovMatrixStorageLocation);
          FileInputStream fileInputStream = null;
          BufferedInputStream bufferedInputStream = null;
          BufferedReader bufferedReader = null;
          String[] statesNames = null;
          String key;
          String startState;
          String endState;
  
          Map<String, Double> transitionCount = new HashMap<String, Double>();
          Map<String, Double> startStateCount = new HashMap<String, Double>();
  
          try {
  
              fileInputStream = new FileInputStream(file);
              bufferedInputStream = new BufferedInputStream(fileInputStream);
              bufferedReader = new BufferedReader(new InputStreamReader(bufferedInputStream));
              int rowNumber = 0;
              String row = bufferedReader.readLine();
              if (row != null) {
                  statesNames = row.split(",");
              }
  
              while ((row = bufferedReader.readLine()) != null) {
  
                  if (rowNumber >= statesNames.length) {
                      throw new OperationNotSupportedException(
                              "Number of rows in the matrix should be equal to number of states. please provide a "
                                      + statesNames.length + " x " + statesNames.length + " matrix.");
                  }
  
                  startState = statesNames[rowNumber];
                  String[] values = row.split(",");
                  double totalCount = 0.0;
  
                  if (values.length != statesNames.length) {
                      throw new OperationNotSupportedException(
                              "Number of columns in the matrix should be equal to number of states. please provide a "
                                      + statesNames.length + " x " + statesNames.length + " matrix.");
                  }
  
                  for (String value : values) {
                      try {
                          totalCount = totalCount + Double.parseDouble(value);
                      } catch (NumberFormatException e) {
                          log.error("Exception occurred while reading the data file: " + markovMatrixStorageLocation
                                  + ". All values in the matrix should be in double.", e);
                      }
                  }
                  startStateCount.put(startState, totalCount);
  
                  for (int j = 0; j < statesNames.length; j++) {
                      endState = statesNames[j];
                      key = markovMatrix.getKey(startState, endState);
                      transitionCount.put(key, Double.parseDouble(values[j]));
                  }
                  rowNumber++;
              }
  
          } catch (IOException e) {
              log.error("Exception occurred while reading the data file: " + markovMatrixStorageLocation, e);
          } finally {
              closedQuietly(markovMatrixStorageLocation, bufferedReader, bufferedInputStream, fileInputStream);
          }
          markovMatrix.setStartStateCount(startStateCount);
          markovMatrix.setTransitionCount(transitionCount);
      }
input: #vulnerable code 
                                  private void populateMarkovMatrix(String markovMatrixStorageLocation) {
  
          File file = new File(markovMatrixStorageLocation);
          FileInputStream fileInputStream = null;
          BufferedInputStream bufferedInputStream = null;
          BufferedReader bufferedReader = null;
          String[] statesNames = null;
          String key;
          String startState;
          String endState;
  
          Map<String, Double> transitionCount = new HashMap<String, Double>();
          Map<String, Double> startStateCount = new HashMap<String, Double>();
  
          try {
  
              fileInputStream = new FileInputStream(file);
              bufferedInputStream = new BufferedInputStream(fileInputStream);
              bufferedReader = new BufferedReader(new InputStreamReader(bufferedInputStream));
              int rowNumber = 0;
              String row = bufferedReader.readLine();
              if (row != null) {
                  statesNames = row.split(",");
              }
  
              while ((row = bufferedReader.readLine()) != null) {
  
                  if (rowNumber >= statesNames.length) {
                      throw new OperationNotSupportedException(
                              "Number of rows in the matrix should be equal to number of states. please provide a "
                                      + statesNames.length + " x " + statesNames.length + " matrix");
                  }
  
                  startState = statesNames[rowNumber];
                  String[] values = row.split(",");
                  double totalCount = 0.0;
  
                  if (values.length != statesNames.length) {
                      throw new OperationNotSupportedException(
                              "Number of columns in the matrix should be equal to number of states. please provide a "
                                      + statesNames.length + " x " + statesNames.length + " matrix");
                  }
  
                  for (String value : values) {
                      try {
                          totalCount = totalCount + Double.parseDouble(value);
                      } catch (NumberFormatException e) {
                          log.error("Exception occurred while reading the data file " + markovMatrixStorageLocation
                                  + ". All values in the matrix should be in double", e);
                      }
                  }
                  startStateCount.put(startState, totalCount);
  
                  for (int j = 0; j < statesNames.length; j++) {
                      endState = statesNames[j];
                      key = markovMatrix.getKey(startState, endState);
                      transitionCount.put(key, Double.parseDouble(values[j]));
                  }
                  rowNumber++;
              }
  
          } catch (IOException e) {
              log.error("Exception occurred while reading the data file " + markovMatrixStorageLocation, e);
          } finally {
              closeQuietly(bufferedReader, bufferedInputStream, fileInputStream);
          }
          markovMatrix.setStartStateCount(startStateCount);
          markovMatrix.setTransitionCount(transitionCount);
      } 
                              #location 65 
                              #vulnerability type NULL_DEREFERENCE