android - how to avoid the null value for bitmap images -

i have made program upload image , has 2 buttons 1 pick image fom gallary , upload database if click upload button without choosing image face null value ,how can avoid it.? 1 me.

here upload code:

    public void insertimage() {     class updateemployee extends asynctask<void, void, string> {          string image = getstringimage(bitmap);           progressdialog loading;          @override         protected void onpreexecute() {             super.onpreexecute();             loading = progressdialog.show(settings.this, "updating...", "wait...", false, false);         }          @override         protected void onpostexecute(string s) {             super.onpostexecute(s);             loading.dismiss();             toast.maketext(settings.this, s, toast.length_long).show();         }          @override         protected string doinbackground(void... params) {             hashmap<string, string> hashmap = new hashmap<>();             hashmap.put(config.key_job_user_id, userdetails.user_id);             hashmap.put(config.tag_image, image);              requesthandler rh = new requesthandler();             string s = rh.sendpostrequest(config.url_update_emp, hashmap);             return s;         }     }     updateemployee ue = new updateemployee();     ue.execute(); } 

here getstingimage method:

  public string getstringimage(bitmap bmp) {      bytearrayoutputstream baos = new bytearrayoutputstream();     bmp.compress(bitmap.compressformat.jpeg, 30, baos);     byte[] imagebytes = baos.tobytearray();     return base64.encodetostring(imagebytes, base64.default); } 

just change:

updateemployee ue = new updateemployee(); ue.execute(); 

to:

if (bitmap != null) {  updateemployee ue = new updateemployee(); ue.execute();  } 

no?