Check out example codes for "select photo from camera android". It will help you in understanding the concepts better.

Code Example 1

private void pickFromGallery(){
       //Create an Intent with action as ACTION_PICK
       Intent intent=new Intent(Intent.ACTION_PICK);
       // Sets the type as image/*. This ensures only components of type image are selected
       intent.setType("image/*");
       //We pass an extra array with the accepted mime types. This will ensure only components with these MIME types as targeted.
       String[] mimeTypes = {"image/jpeg", "image/png"};
       intent.putExtra(Intent.EXTRA_MIME_TYPES,mimeTypes);
       // Launching the Intent 
       startActivityForResult(intent,GALLERY_REQUEST_CODE);
   }

    public void onActivityResult(int requestCode,int resultCode,Intent data){
          // Result code is RESULT_OK only if the user selects an Image
          if (resultCode == Activity.RESULT_OK)
          switch (requestCode){
              case GALLERY_REQUEST_CODE:
                  //data.getData returns the content URI for the selected Image
                  Uri selectedImage = data.getData();
                  imageView.setImageURI(selectedImage);
                  break;
          }
      }

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