Null Pointer Exception while applying conditions

This is a small portion of my code.While running it shows "Unfortunately application is stop".Logcat shows a Null Pointer Exception. if "if-else" condition is not used it execute smoothly. In this case i can't check whether gps is ON/OFF.

 public void runGPSFunction() {
            if(gps.canGetLocation())
            {


            sendSMS.sendSMSMessage();
            }
            else
            {
                gps.showSettingsAlert();
            }

Please help me to solve this.