Uploaded byAlexey Buzdin
Android crashcourse
The document provides an overview of key concepts in Android development including: 1) Android applications are built using Java and XML files and use the Android framework which is based on a component-based model with activities, intents, and manifest files. 2) The project structure separates code, resources, and configuration files. Activities display UI and respond to user input using callbacks. 3) Views display content on screen and are defined in XML layout files then accessed in code. Adapters populate views with data. Intents are used to start activities and pass data.
Android crashcourse
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- 2. Android Java SE +Android.jar Dalvik runtime Component based MVC
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- 4. Project Structure Source codein Java Images, gradients, etc UI written in XML Reference Data (Strings, colors, arrays) App config file
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- 6. Activity public class TestActivityextends Activity { @Override protected void onCreate(Bundle savedState) { super.onCreate(savedState); setContentView(R.layout.main); } }
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- 8. Context Interface to globalinformation about an application environment. Up-calls for application-level operations such as launching activities, broadcasting and receiving intents, etc.
- 9. Context examples TextView text= new TextView(context); new ArrayAdapter(context, R.layout.item, myList) context.getExternalCacheDir() context.getResources() context.startActivity(navigationIntent)
- 10. R.java public class TestActivityextends Activity { @Override protected void onCreate(Bundle savedState) { super.onCreate(savedState); setContentView(R.layout.main); } }
- 11. R.java (resource) Auto generatedinterface between src and android resources. Used only for compilation time.
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- 15. Views Views - TextView,EditText, Button ... ViewGroup - LinearLayout, RelativeLayout ... AdapterView - Spinner, Gallery, ListView ...
- 16. res/layout/ <?xml version="1.0" encoding="utf-8"?> <LinearLayoutxmlns:android="http://schemas. android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> </LinearLayout>
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- 19. Views. Java part @Override protectedvoid onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView text = (TextView) findViewById(R.id.textView); }
- 20. Views. Java part @Override protectedvoid onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView text = (TextView) findViewById(R.id.textView); text.findViewById(0); // same method invocation }
- 21. Under the hood.LayoutInflater LayoutInflater inflater = context.getLayoutInflater(); View view = inflater.inflate(R.layout.main, null);
- 22. Under the hood.LayoutInflater @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); LayoutInflater inflater = context.getLayoutInflater(); View view = inflater.inflate(R.layout.main, null); setContentView(view); TextView text = (TextView) view.findViewById(R.id.textView); }
- 23. Event Handling Button button= new Button(context); button.setOnClickListener(new OnClickListener(){ @Override public void onClick(View v){ Toast.makeText(MyActivity.this, "Hello World", Toast.LENGTH_SHORT).show(); } });
- 24. Event Handling For Views OnLongClickListener OnSelectListener OnHoverListener ..... ForAdapterView OnItemClickListener OnItemLongClickListener
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- 28. AdapterView Gallery gallery =(Gallery) findViewById(R.id.gallery); ArrayList<String> list = new ArrayList<String>(); gallery.setAdapter(new ArrayAdapter<String>(this, 0, list){ @Override public View getView(int position, View convertView, ViewGroup parent) { // 1. Check if view already exists // 2. If not - Inflate view // 3. Populate view return view; } });
- 29. Intent Abstract description ofan operation to be performed. External Intents Open URL Call a Person Share an Image Internal Intents Start Activity
- 30. Example Intent intent =new Intent(context, SecondActivity.class); startActivity(intent); Intent intent = new Intent(context, SecondActivity.class); intent.putExtra("url", url); intent.putExtra("bean", serializable); startActivity(intent);
- 31. Example protected void onCreate(BundlesavedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.article_detail); String s = getIntent().getStringExtra("url"); Bean b = (Bean)getIntent().getSerializableExtra("bean"); }
- 32. AndroidManifest <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="lv.ldn.rssreader" android:versionCode="1" android:versionName="1.0" > <uses-sdkandroid:minSdkVersion="7" android:targetSdkVersion="16" /> <uses-permission android:name="android.permission.INTERNET" /> <application android:icon="@drawable/starred" android:label="@string/app_name"> <activity android:name=".MyActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
- 33. AndroidManifest <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="lv.ldn.rssreader" android:versionCode="1" android:versionName="1.0" > <uses-sdkandroid:minSdkVersion="7" android:targetSdkVersion="16" /> <uses-permission android:name="android.permission.INTERNET" /> <application android:icon="@drawable/starred" android:label="@string/app_name"> <activity android:name=".MyActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name=".SecondActivity"/> </application> </manifest>
- 34. AsyncTask public class MyTaskextends AsyncTask<Integer, Void, String>{ protected void onPreExecute() { } protected String doInBackground(Integer... integers) { return null; } protected void onPostExecute(String result) { } }
- 35. AsyncTask MyTask task =new MyTask(); task.execute(value)