が、私は以下のコードを試してみましたが、そのは

Question

@Override 
public boolean onNavigationItemSelected(MenuItem item) { 
    // Handle navigation view item clicks here. 
    int id = item.getItemId(); 

    if (id == R.id.nav_downloads) { 
     Intent i = new Intent(this,DownloadPage.class); 
     startActivity(i); 
    } else if (id == R.id.nav_gallery) { 

    } else if (id == R.id.nav_settings) { 

     View.OnClickListener listener = new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { // here i want to add fragment 
       Manage manage = new Manage(); 
       FragmentTransaction transaction = fm.beginTransaction(); 
       transaction.add(R.id.downfragment, manage, "Settings"); 
       transaction.commit(); 

      } 
     }; 
    } else if (id == R.id.nav_share) { 

    } else if (id == R.id.nav_send) { 

    } 
} 

Answer 1

が起こっていない、onNavigationItemSelected()はすでに呼び出されます。したがって、次のようにlistenerコードを削除してください。

@Override 
public boolean onNavigationItemSelected(MenuItem item) { 
    // Handle navigation view item clicks here. 
    int id = item.getItemId(); 

    if (id == R.id.nav_downloads) { 
     Intent i = new Intent(this,DownloadPage.class); 
     startActivity(i); 
    } else if (id == R.id.nav_gallery) { 

    } else if (id == R.id.nav_settings) { 

     Manage manage = new Manage(); 
     FragmentTransaction transaction = fm.beginTransaction(); 
     transaction.add(R.id.downfragment, manage, "Settings"); 
     transaction.commit(); 


} else if (id == R.id.nav_share) { 

} else if (id == R.id.nav_send) { 

} 
}