Android University - Week 6

Transcript

1. Android University Week 6: Instagram (Part 2)
2. Instagram (Part 1) - User can create a new account - User can log in / out - User can create a post with a photo and caption
3. Instagram (Part 2) • User can view most recent 20 posts
4. Instagram (Part 2) • User can view most recent 20 posts • User can pull to refresh the most recent 20 posts
5. Instagram (Part 2) • User can view most recent 20 posts • User can pull to refresh the most recent 20 posts • The user can switch between different tabs
 - viewing all posts (feed)
 - capture (creation)
 - profile tabs (stream)
7. Bottom Navigation Bar
8. Bottom Navigation Bar • Good for:
 - Top-level destinations that need to be accessible from anywhere in the app

9. Bottom Navigation Bar • Good for:
 - Top-level destinations that need to be accessible from anywhere in the app
 • NOT good for:
 - Obscure tasks the user never really needs
10. Fragments
11. What are Fragments? • Pretty similar to activities! (but cannot live by itself, must be embedded in an Activity)
12. What are Fragments? • Pretty similar to activities! (but cannot live by itself, must be embedded in an Activity) • Can have multiple Fragments on the screen at the same time
13. Fragments and Nav Bars
14. Fragments and Nav Bars CREATE
15. Fragments and Nav Bars HOME CREATE PROFILE
16. How do we build Fragments?
17. How do we build Fragments? • Similar to an Activity
 Java File + XML layout
18. How do we build Fragments? • Similar to an Activity
 Java File + XML layout public class ExampleFragment extends Fragment { @Override public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) { return inflater.inflate(R.layout.feed_fragment, parent); } // Any view setup should occur here. E.g., view lookups and attaching view listeners. @Override public void onViewCreated(View view, Bundle savedInstanceState) { } }
19. How do we build Fragments? • Similar to an Activity
 Java File + XML layout public class ExampleFragment extends Fragment { @Override public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) { return inflater.inflate(R.layout.feed_fragment, parent); } // Any view setup should occur here. E.g., view lookups and attaching view listeners. @Override public void onViewCreated(View view, Bundle savedInstanceState) { } } <RelativeLayout xmlns:android="http:// schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent"> <Button android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:text="@string/login_label" /> </RelativeLayout> R.layout.feed_fragment
20. Fragment Lifecycle
21. Fragment Lifecycle (the important parts) onCreateView() onViewCreated()
22. Fragment Lifecycle (the important parts) onCreateView() - inflate fragment layout
 inflator.inflate(R.layout.feed_fragment, parent);
23. Fragment Lifecycle (the important parts) onCreateView() - inflate fragment layout
 inflator.inflate(R.layout.feed_fragment, parent); onViewCreated() - setting up views and attaching listeners
 feedRecyclerView = findViewById(R.id.feedRv); button = findViewById(R.id.barrier); button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { } });
24. Fragment Lifecycle (the important parts) onCreateView() - inflate fragment layout
 inflator.inflate(R.layout.feed_fragment, parent); onViewCreated() - setting up views and attaching listeners
 feedRecyclerView = findViewById(R.id.feedRv); button = findViewById(R.id.barrier); button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { } });
25. Activities and Fragments
26. Activities and Fragments // Replace the contents of the container with the new fragment getSupportFragmentManager() .beginTransaction() .replace(R.id.flContainer, new FooFragment()) .commit(); MainActivity.java
27. Activities and Fragments // Replace the contents of the container with the new fragment getSupportFragmentManager() .beginTransaction() .replace(R.id.flContainer, new FooFragment()) .commit(); <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" > <FrameLayout android:id="@+id/flContainer" android:layout_width="match_parent" android:layout_height="match_parent"/> </RelativeLayout> activity_main.xml MainActivity.java
28. In Summary Fragments are like ‘mini’ Activities

29. In Summary Fragments are like ‘mini’ Activities
 made up of Java class + XML file

30. In Summary Fragments are like ‘mini’ Activities
 made up of Java class + XML file
 has their own lifecycle callbacks

31. In Summary Fragments are like ‘mini’ Activities
 made up of Java class + XML file
 has their own lifecycle callbacks
 must live in an Activity
32. In Summary Fragments are like ‘mini’ Activities
 made up of Java class + XML file
 has their own lifecycle callbacks
 must live in an Activity When Activities contain Fragments, the Activity controls which Fragment to show. The rest of the logic goes in the Fragment (setting up views, handling clicks, making network calls…)