java - Check files exist in a directory -

i want read files in folder using java. unfortunately files missing , npe.

public static hashmap<string, integer> getcputemp() throws ioexception     {         file directory = new file("/sys/devices/virtual/thermal");          if (directory.exists())         {             hashmap<string, integer> usagedata = new hashmap<>();              file[] flist = directory.listfiles();              (file file : flist)             {                 if (file.isdirectory() && file.getname().startswith("thermal_zone"))                 {                     ......................                 }             }             return usagedata;         }         return null; 

how can prevent , return null if files not there? can show me solution java 8?

i npe here (file file : flist)

it should flist null.

so, right after flist creation, check null.

file[] flist = directory.listfiles(); if (flist == null) {     return null; }