Practical Implementation of Up Navigation Keisuke Kobayashi (@kobakei) potatotips #38

About me • Keisuke Kobayashi • Coubic Inc • GitHub, Qiita: @kobakei • Twitter: @ksk_kbys • Android, Rails, React

Up Navigation?

Up Back

Back vs Up • Back • Navigate to previous screen which may be other app • Up • Navigate to parent screen in same app

Example

EC app • Timeline > Detail • Timeline > Search > Detail • Timeline > Detail > Detail • Recommendation, similar items, … • Deep link > Detail • Notification, Google search result, …

Navigation Flow 5JNFMJOF 4FBSDI %FUBJM (deep link)

Navigation Flow 5JNFMJOF 4FBSDI %FUBJM (deep link) From search

Navigation Flow 5JNFMJOF 4FBSDI %FUBJM (deep link) Otherwise From search

How to implement?

Just calling 
 Activity#finish() ?

Calling Activity#finish() ? @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case android.R.id.home: finish(); return true; } return super.onOptionsItemSelected(item); }

Calling Activity#finish() ? • May be OK in simple flow • NG in Timeline > Detail > Detail flow • It opens previous Detail screen… • NG in deep link flow • It closes app…

OK, I will copy & paste from developer.android.com

developer.android.com @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { // Respond to the action bar's Up/Home button case android.R.id.home: NavUtils.navigateUpFromSameTask(this); return true; } return super.onOptionsItemSelected(item); }

Something wrong…

What is wrong? 1. Recreated parent activity • Scroll position, bottom navigation etc 2. Always same parent activity regardless of where it comes from

What is wrong? 1. Recreated parent activity • Scroll position, bottom navigation etc 2. Always same parent activity regardless of where it comes from

Avoid recreating parent @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case android.R.id.home: Intent upIntent = NavUtils.getParentActivityIntent(this); upIntent.addFlags( Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP); startActivity(upIntent); finish(); return true; } return super.onOptionsItemSelected(item); }

What is wrong? 1. Recreated parent activity • Scroll position, bottom navigation etc 2. Always same parent activity regardless of where it comes from

Set parent activity class to bundle extra // DetailActivity#createIntent public static Intent createIntent( @NonNull Context context, @Nullable Class extends Activity> parentClass) { Intent intent = new Intent(context, DetailActivity.class); if (parentClass != null) { intent.putExtra(KEY_PARENT, parentClass.getName()); } return intent; }

Restore parent activity class
 from bundle extra // Parent activity class private Class parentClass; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // … String parentClassName = getIntent().getStringExtra(KEY_PARENT); if (TextUtils.isEmpty(parentClassName)) { parentClass = MainActivity.class; } else { try { parentClass = Class.forName(parentClassName); } catch (ClassNotFoundException e) { Timber.e(e); } } }

Create up intent with 
 parent activity class @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case android.R.id.home: Intent upIntent = new Intent(getApplicationContext(), parentClass); upIntent.addFlags( Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP); startActivity(upIntent); finish(); return true; } return super.onOptionsItemSelected(item); }

Complete

Conclusion • Explained how to implement UP navigation in complex flow • Key points • FLAG_ACTIVITY_CLEAR_TOP | FLAG_ACTIVITY_SINGE_TOP • Set parent class in bundle extra and use for Intent to parent activity

Appendix • ͪΐͬͱෳࡶͳUPϘλϯͷ࣮૷ in Qiita • http://qiita.com/kobakei/items/ ae1a6d2062f34d3f6771 • DroidKaigi 2017 app

Thanks!