Android directly opens the system photo album app to view photos instead of selecting pictures

Android directly opens the system album to view photos instead of selecting pictures. The
code is as follows:

Intent intent = new Intent();
        intent.setAction(Intent.ACTION_MAIN); 
        intent.addCategory(Intent.CATEGORY_APP_GALLERY);
        startActivity(intent);

悟已往之不谏，知来者之可追。    ------《归去来兮辞》