android - How to enlarge a picture in Gridview when it is clicked using a new activity? -

so have activity inflates gridview, , want clickable, , upon click, opens new activity, shows whole image, along texts i've written in activity. note confirmed txt file written written successfully, , in sd card.

here code gridview activity

public class gridview extends appcompatactivity {  android.widget.gridview gv; arraylist<file> list,list2;  @override protected void oncreate(@nullable bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.gallery);      file dir = new file(environment.getexternalstoragedirectory().getabsolutepath() + "/mycameraapp");     file dir2 = new file(environment.getexternalstoragedirectory().getabsolutepath() + "/mycameraapp");     list = imagereader(dir);     list2 = locationreader(dir2);       gv = (android.widget.gridview) findviewbyid(r.id.gridview);     gv.setadapter(new gridadapter());      gv.setonitemclicklistener(new adapterview.onitemclicklistener() {         @override         public void onitemclick(adapterview<?> parent, view view, int position, long id) {             intent intent = new intent(gridview.this, viewimage.class);             intent.putextra("myimage", list.get(position));             intent.putextra("mylocation", list2.get(position));             startactivity(intent);             //startactivity(new intent(getapplicationcontext(), viewimage.class).putextra("img",list.get(position)));         }     }); }  public void backtomain(view view) {     intent backtomain = new intent(this, mainactivity.class);     startactivity(backtomain); }  class gridadapter extends baseadapter{      @override     public int getcount() {         return list.size();     }      @override     public object getitem(int position) {         return list.get(position);     }      @override     public long getitemid(int position) {         return 0;     }      @override     public view getview(int position, view convertview, viewgroup parent) {         convertview = getlayoutinflater().inflate(r.layout.simple_grid, parent, false);         imageview iv = (imageview) convertview.findviewbyid(r.id.imageview);         iv.setimageuri(uri.parse(getitem(position).tostring()));          return convertview;     } }   arraylist<file> imagereader(file root){     arraylist<file> = new arraylist<>();      file[] files = root.listfiles();     for(int = 0; < files.length; i++){         if(files[i].isdirectory()){          }         else         {             if(files[i].getname().endswith(".jpg")){                 a.add(files[i]);             }         }     }     return a; } arraylist<file> locationreader(file root){     arraylist<file> = new arraylist<>();      file[] files = root.listfiles();     for(int = 0; < files.length; i++){         if(files[i].isdirectory()){          }         else         {             if(files[i].getname().endswith(".txt")){                 a.add(files[i]);             }         }     }     return a; }  } 

here activity that's called gridview, supposedly show image plus open file i've written earlier, , show content (a string).

public class viewimage extends appcompatactivity {  imageview imageview; textview textview;  @override protected void oncreate(@nullable bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.view_image);   //   int image = getintent().getextras().getint("myimage", r.drawable.common_google_signin_btn_text_light);     int image = getintent().getintextra("myimage", r.drawable.cast_ic_notification_0);     imageview imageview = (imageview) findviewbyid(r.id.imageview2);     imageview.setimageresource(image);      intent calledactivity = getintent();      string pos = calledactivity.getextras().getstring("mylocation");     textview = (textview) findviewbyid(r.id.text_location);     textview.settext(pos);  }  public void backtocamera(view view) {     intent intent = new intent(viewimage.this, mainactivity.class);     startactivity(intent); } } 

right now, see r.drawable.cast_ic_notification_0 being picture, opposed gridview's image. also, textview empty, used debugger , showed

string pos = calledactivity.getextras().getstring("mylocation"); 

pos null. please help!

list.get(position) file , you're trying read getextras().getint()

i think should pass file path string:

intent.putextra("myimage", list.get(position).getabsolutepath()); 

and receive it:

file imgfile = new  file(getintent().getstringextra("myimage")); if(imgfile.exists()){     bitmap mybitmap = bitmapfactory.decodefile(imgfile.getabsolutepath());     imageview imageview = (imageview) findviewbyid(r.id.imageview2);     imageview.setimagebitmap(mybitmap); }