Android Programming Introduction

An introduction to Android programming with fundamental concepts, including activity life cycle and fragment. The slides are based on book "The Big Nerd Ranch Guide" and some images are from site of Android Developer.

Transcript

1. Android Programming Reading “The Big Nerd Ranch Guide” Bruce Tsai
2. Activity States Resumed (Running) Paused Stopped 2
3. Text Activity Lifecycle Back? Home? 3
4. Text Back Stack Intact Last in, first out 4
5. Multitasks Task is cohesive unit that can move to “background” when user begins a new task or go to Home screen 5
6. Text Start Other Activity Via ActivityManager 6
7. Intent Object that component uses to communicate with OS Explicit intent — start activities within application create Intent with Context and Class Implicit intent — start activities in another application 7
8. Intent i = new Intent(QuizActivity.this, CheatActivity.class);! startActivity(i); 8
9. Put Intent Extras (parent) Intent i = new Intent(QuizActivity.this, CheatActivity.class);! i.putExtra(CheatActivity.EXTRA_ANSWER_IS_ TRUE, true);! startActivity(i); 9
10. Use Intent Extra (child) mAnswerIsTrue = getIntent().getBooleanExtra(EXTRA_ANSWER_ IS_TRUE, false); 10
12. Get Activity Result Intent i = new Intent(QuizActivity.this, CheatActivity.class);! i.putExtra(CheatActivity.EXTRA_ANSWER_IS_ TRUE, true);! startActivity(i);! startActivityForResult(i, 0); 12
13. Set Result (child) Intent data = new Intent();! data.putExtra(EXTRA_ANSWER_SHOWN, true);! setResult(RESULT_OK, data); 13
14. Handle Result (parent) protected void onActivityResult(int requestCode, int resultCode, Intent data) {! ! if (data == null) return;! ! mIsCheater = ! data.getBooleanExtra(CheatActivity.EXTRA_A NSWER_SHOWN, false);! } 14
15. Fragment Controller object that activity can deputize to perform tasks 15
16. Support Library Fragment is introduced from API level 11 16
17. Fragment Host Activity defines a spot in its layout for fragment’s view Activity manage lifecycle of fragment instance Hosting approaches: add to layout or add to code 17
18. Fragment Manager 18
19. Fragment Transaction Usages of fragment in activities are add, remove, replace and perform other actions Each set of changes that is committed to activity is fragment transaction 19
20. FragmentManager fm = getSupportFragmentManager();! Fragment fragment = fm.findFragmentById(R.id.fragmentContainer);! if (fragment == null) {! ! fragment = new CrimeFragment();! ! fm.beginTransaction()
 ! .add(R.id.fragmentContainer)
 ! .commit();! } 20
21. SDK Versions Minimum SDK version — hard floor below which the OS should refuse to install the app Target SDK version — API level the app is designed to run on Build SDK version — private information between you and compiler 21
22. dp (dip) — density-independent pixel sp — scale-independent pixel 22
23. <Button
 ! android:layout_width=“wrap_content”
 ! android:layout_weight=“1” />! <CheckBox
 ! android:layout_width=“wrap_content”
 ! android:layout_weight=“1” />