java - Null pointer when reading a Properties file from another folder -

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• what nullpointerexception, , how fix it? 12 answers

my application check if properties file exists , create 1 if not.

try{         // create new file          string path="c:\\temp\\lasercontroller.properties";         file file = new file(path);         string comport = "comport=com1";         string parity = "parity=none";         string baud = "baud=9600";         string stopbits = "stopbits=0";         string databits = "databits=8";            // if file doesnt exists, create            if (!file.exists()) {                file.createnewfile();               filewriter fw = new filewriter(file.getabsolutefile());            bufferedwriter bw = new bufferedwriter(fw);            // write in file            bw.write(comport);            bw.newline();            bw.write(parity);            bw.newline();            bw.write(baud);            bw.newline();            bw.write(stopbits);            bw.newline();            bw.write(databits);            // close connection            bw.close();            } 

but when try read properties file null pointer.

else {            properties prop = new properties();               inputstream input = lasercontrollerui.class.getresourceasstream("c:\\temp\\lasercontroller.properties");               // load properties file             prop.load(input);              // property value , print out             system.out.println(prop.getproperty(comport+"comport"));             system.out.println(prop.getproperty("parity"));             system.out.println(prop.getproperty("baud"));             input.close();          }      }catch(exception e){          system.out.println(e);      } }        

it fails on inputstream input line dont know why. file exists , application can access because put there in first place. doing wrong?

the file has in location accessible users change parameters.

getresourceasstream method needs "class-path relative" name. providing absolute path. try use fileinputstream instead.

e.g:

inputstream input = new fileinputstream("c:\\temp\\lasercontroller.properties");