Android development

Июль 23, 2022

Содержание

2. ANDROID HISTORY Android is an open source and Linux-based Operating System for mobile devices such as
4. REQUIRED TOOLS Java JDK5 or later version Java Runtime Environment (JRE) 6 Android SDK Android Studio
6. PROJECT FOLDERS src - This contains the .java source files for your project. By default, it
7. ACTIVITIES An activity represents a single screen with a user interface, in-short Activity performs actions on
9. LAYOUT android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" > android:layout_width="wrap_content“ android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_centerVertical="true" android:text="@string/hello_world"/>
10. MANIFEST package="com.example.helloworld" android:versionCode="1" android:versionName="1.0" > android:minSdkVersion="8" android:targetSdkVersion="22" /> android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > android:name=".MainActivity“ android:label="@string/title_activity_main" >
11. BUILDING WITH GRADLE apply plugin: 'com.android.application' android { compileSdkVersion 23 buildToolsVersion "23.0.3" defaultConfig { applicationId "com.resentient.hwat"
13. PASSING DATA BETWEEN ACTIVITIES Ways to pass data between activities: Save the data in a database
14. SHARED PREFERENCES Shared Preferences allow you to save and retrieve data in the form of key-value
15. INTENT An Intent in the Android operating system is a software mechanism that allows users to
16. Starting camera example: Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); Uril file = Uri.fromFile(new File(pathToImage)); intent.putExtra(MediaStore.EXTRA_OUTPUT, file); startActivityForResult(intent,
17. Sharing in facebook example: public void shareOnFacebook(View view) { Uri uri = Uri.fromFile(takeScreenshot()); Intent sharingIntent =
18. GET VIEW ELEMENTS FROM ACTIVITY ImageView takenPhoto = (ImageView) findViewById(R.id.imageView); takenPhoto.setImageBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.correct)); takenPhoto.setVisibility(View.INVISIBLE);
19. ADDING LISTENERS TO ELEMENTS final Button button = (Button) findViewById(R.id.button_id); button.setOnClickListener(new View.OnClickListener() { @Override public void
20. ON TOUCH AND SWIPE EVENTS @Override public boolean onTouchEvent(MotionEvent event) { int action = event.getActionMasked(); switch
21. case MotionEvent.ACTION_UP: float finalX = event.getX(); float finalY = event.getY(); Log.d(TAG, "Action was UP"); if (initialX
22. DIALOG WINDOWS final Dialog dialog = new Dialog(this); dialog.requestWindowFeature(Window.FEATURE_NO_TITLE); dialog.setContentView(R.layout.share_dialog); dialog.setCanceledOnTouchOutside(true); dialog.show();
23. CHECK INTERNET CONNECTION ConnectivityManager connectivity = (ConnectivityManager) getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE); if (connectivity != null) { NetworkInfo info =
24. ASYNC TASK class DataLoader extends AsyncTask { @Override protected Void doInBackground(Void... params) { insertLevelsDataIntoDatabase(); return null;
25. SQLITE Creating database: public class DatabaseCreator extends SQLiteOpenHelper { public DatabaseCreator(Context context) { super(context, “MyDatabase”, null,
26. Inserting data into database: DatabaseCreator dbHelper = new DatabaseCreator(context); SQLiteDatabase db = dbHelper.getWritableDatabase(); ContentValues cv =
27. Fetching data from database: DatabaseCreator dbHelper = new DatabaseCreator(context); SQLiteDatabase db = dbHelper.getWritableDatabase(); Cursor cursor =
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ANDROID HISTORY
Android is an open source and Linux-based Operating System for mobile devices

such as smartphones and tablet computers. Android was developed by the Open Handset Alliance, led by Google, and other companies.
The first beta version of the Android Software Development Kit (SDK) was released by Google in 2007 where as the first commercial version, Android 1.0, was released in September 2008.

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REQUIRED TOOLS
Java JDK5 or later version
Java Runtime Environment (JRE) 6
Android SDK
Android

Studio
Eclipse IDE for Java Developers
ADB Driver

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PROJECT FOLDERS
src - This contains the .java source files for your project.

By default, it includes a MainActivity.java source file having an activity class that runs when your app is launched using the app icon.
res/drawable - This is a directory for drawable objects that are designed for high-density screens.
res/layout - This is a directory for files that define your app's user interface.
res/values - This is a directory for other various XML files that contain a collection of resources, such as strings and colors definitions.
AndroidManifest.xml - This is the manifest file which describes the fundamental characteristics of the app and defines each of its components.

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ACTIVITIES
An activity represents a single screen with a user interface, in-short

Activity performs actions on the screen. For example, an email application might have one activity that shows a list of new emails, another activity to compose an email, and another activity for reading emails. If an application has more than one activity, then one of them should be marked as the activity that is presented when the application is launched.
public class MainActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main);
}
}

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LAYOUT
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
android:layout_width="wrap_content“
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="@string/hello_world"/>

Слайд 10

MANIFEST
package="com.example.helloworld"
android:versionCode="1"
android:versionName="1.0" >
android:minSdkVersion="8"
android:targetSdkVersion="22" />

/>
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
android:name=".MainActivity“
android:label="@string/title_activity_main" >

Слайд 11

BUILDING WITH GRADLE
apply plugin: 'com.android.application' android { compileSdkVersion 23 buildToolsVersion "23.0.3" defaultConfig

{ applicationId "com.resentient.hwat" versionCode 2 versionName "1.0.2" } } dependencies { testCompile 'junit:junit:4.12' compile 'com.android.support:appcompat-v7:23.4.0' compile 'com.clarifai:clarifai-api-java:1.2.0' }

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PASSING DATA BETWEEN ACTIVITIES
Ways to pass data between activities:
Save the data

in a database
Save the data in a file
Use Shared preferences
Use Intent

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SHARED PREFERENCES
Shared Preferences allow you to save and retrieve data in

the form of key-value pair. Shared Preferences values will persist across user sessions. Data in shared preferences will be persistent even though user closes the application. You can get values from Shared preferences using getSharedPreferences() method.
SharedPreferences sharedProperties = getSharedPreferences(“MyPreferences”, Context.MODE_PRIVATE);
if (sharedProperties.getBoolean(“LaunchedFirstly”, true)) {
SharedPreferences.Editor e = sharedProperties.edit(); e.putBoolean(“LaunchedFirstly”, false); e.commit();
}

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INTENT
An Intent in the Android operating system is a software mechanism that allows users to start some actions

or just passing some info between two activities.
Example:
Intent i = new Intent(getApplicationContext(), MyActivity.class);
i.putExtra("name", “Ihor");
i.putExtra("surname", “Sokolyk";
startActivity(i);
Intent intent = getIntent();
String message = intent.getStringExtra(“name");

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Starting camera example:
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); Uril file = Uri.fromFile(new File(pathToImage)); intent.putExtra(MediaStore.EXTRA_OUTPUT,

file); startActivityForResult(intent, 100);
@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == 100) { if (resultCode == RESULT_OK) { takenPhoto.setImageURI(file); } } }

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Sharing in facebook example:
public void shareOnFacebook(View view) { Uri uri =

Uri.fromFile(takeScreenshot()); Intent sharingIntent = new Intent(android.content.Intent.ACTION_SEND); sharingIntent.setType("image/*"); sharingIntent.putExtra(Intent.EXTRA_STREAM, uri); setDefaultPackageForIntent(sharingIntent, "com.facebook"); if (sharingIntent.getPackage() != null) { startActivity(sharingIntent); } else { Toast.makeText(getApplicationContext(), “Facebook not installed”, Toast.LENGTH_SHORT).show(); } }

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GET VIEW ELEMENTS FROM ACTIVITY
ImageView takenPhoto = (ImageView) findViewById(R.id.imageView);
takenPhoto.setImageBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.correct));
takenPhoto.setVisibility(View.INVISIBLE);

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ADDING LISTENERS TO ELEMENTS
final Button button = (Button) findViewById(R.id.button_id); button.setOnClickListener(new View.OnClickListener() {

@Override public void onClick(View v) { // Perform action on click } });

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ON TOUCH AND SWIPE EVENTS
@Override
public boolean onTouchEvent(MotionEvent event) {
int action =

event.getActionMasked();
    switch (action) {
        case MotionEvent.ACTION_DOWN:
            initialX = event.getX();
            initialY = event.getY();
            Log.d(TAG, "Action was DOWN");
            break;
        case MotionEvent.ACTION_MOVE:
            Log.d(TAG, "Action was MOVE");
            break;

Слайд 21

case MotionEvent.ACTION_UP:
            float finalX = event.getX();
            float finalY = event.getY();
            Log.d(TAG, "Action was UP");
            if

(initialX < finalX) {
                Log.d(TAG, "Left to Right swipe performed");
            }
            if (initialX > finalX) {
                Log.d(TAG, "Right to Left swipe performed");
            }
            if (initialY < finalY) {
                Log.d(TAG, "Up to Down swipe performed");
            }
            if (initialY > finalY) {
                Log.d(TAG, "Down to Up swipe performed");
            }
            break;
}
return super.onTouchEvent(event);
}

Слайд 22

DIALOG WINDOWS
final Dialog dialog = new Dialog(this); dialog.requestWindowFeature(Window.FEATURE_NO_TITLE); dialog.setContentView(R.layout.share_dialog); dialog.setCanceledOnTouchOutside(true); dialog.show();

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CHECK INTERNET CONNECTION
ConnectivityManager connectivity = (ConnectivityManager) getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE); if (connectivity != null)

{ NetworkInfo info = connectivity.getActiveNetworkInfo(); if (info != null) if (info.getState() == NetworkInfo.State.CONNECTED) { Toast.makeText(getApplicationContext(), “Connected”, Toast.LENGTH_SHORT).show(); } }

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ASYNC TASK
class DataLoader extends AsyncTask { @Override protected Void

doInBackground(Void... params) { insertLevelsDataIntoDatabase(); return null; } @Override protected void onPostExecute(Void aVoid) { new android.os.Handler().postDelayed( new Runnable() { public void run() { Intent intent = new Intent(getApplicationContext(), WelcomeActivity.class); startActivity(intent); finish(); } }, 2000); super.onPostExecute(aVoid); } }
DataLoader dataLoader = new DataLoader(); dataLoader.execute();

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SQLITE
Creating database:
public class DatabaseCreator extends SQLiteOpenHelper { public DatabaseCreator(Context context) {

super(context, “MyDatabase”, null, 1); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL("CREATE TABLE IF NOT EXISTS levels (" + "id integer primary key autoincrement," + "levelId integer NOT NULL," + "question text NOT NULL," + "answer text NOT NULL," + "type text NOT NULL," + "image BLOB default NULL," + "isLevelCompleted integer);"); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { } }

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Inserting data into database:
DatabaseCreator dbHelper = new DatabaseCreator(context);
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues

cv = new ContentValues();
cv.put(“levelId”, 1); cv.put(“question”,”Catch smile”); cv.put(“answer”, “smile”); cv.put(“type”, “emotion”); if (db.update(“levels”, cv, “levelId = " + 1, null) == 0) { db.insert(“levels”, null, cv); }
cv.clear();

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Fetching data from database:
DatabaseCreator dbHelper = new DatabaseCreator(context);
SQLiteDatabase db = dbHelper.getWritableDatabase();
Cursor

cursor = db.rawQuery("SELECT * FROM levels WHERE levelId = 1", null);
if (cursor.moveToFirst()) { do { levelQuestion = cursor.getString(cursor.getColumnIndex(“question”)); levelAnswer = cursor.getString(cursor.getColumnIndex(“answer”)); levelType = cursor.getString(cursor.getColumnIndex(“type”)); correctImage = cursor.getBlob(cursor.getColumnIndex(“image”)); } while (cursor.moveToNext()); } cursor.close();

Android development

Содержание

ANDROID HISTORYAndroid is an open source and Linux-based Operating System for mobile devices

REQUIRED TOOLSJava JDK5 or later versionJava Runtime Environment (JRE) 6Android SDKAndroid

PROJECT FOLDERS src - This contains the .java source files for your project.

ACTIVITIESAn activity represents a single screen with a user interface, in-short

LAYOUT android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" > android:layout_width="wrap_content“ android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_centerVertical="true" android:text="@string/hello_world"/>

MANIFEST package="com.example.helloworld" android:versionCode="1" android:versionName="1.0" > android:minSdkVersion="8" android:targetSdkVersion="22" />

BUILDING WITH GRADLEapply plugin: 'com.android.application' android { compileSdkVersion 23 buildToolsVersion "23.0.3" defaultConfig

PASSING DATA BETWEEN ACTIVITIESWays to pass data between activities:Save the data

SHARED PREFERENCESShared Preferences allow you to save and retrieve data in

INTENTAn Intent in the Android operating system is a software mechanism that allows users to start some actions

Starting camera example:Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); Uril file = Uri.fromFile(new File(pathToImage)); intent.putExtra(MediaStore.EXTRA_OUTPUT,

Sharing in facebook example:public void shareOnFacebook(View view) { Uri uri =

GET VIEW ELEMENTS FROM ACTIVITYImageView takenPhoto = (ImageView) findViewById(R.id.imageView);takenPhoto.setImageBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.correct));takenPhoto.setVisibility(View.INVISIBLE);

ADDING LISTENERS TO ELEMENTSfinal Button button = (Button) findViewById(R.id.button_id); button.setOnClickListener(new View.OnClickListener() {

ON TOUCH AND SWIPE EVENTS@Overridepublic boolean onTouchEvent(MotionEvent event) { int action =

case MotionEvent.ACTION_UP: float finalX = event.getX(); float finalY = event.getY(); Log.d(TAG, "Action was UP"); if

DIALOG WINDOWSfinal Dialog dialog = new Dialog(this); dialog.requestWindowFeature(Window.FEATURE_NO_TITLE); dialog.setContentView(R.layout.share_dialog); dialog.setCanceledOnTouchOutside(true); dialog.show();

CHECK INTERNET CONNECTION ConnectivityManager connectivity = (ConnectivityManager) getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE); if (connectivity != null)

ASYNC TASKclass DataLoader extends AsyncTask { @Override protected Void

SQLITECreating database:public class DatabaseCreator extends SQLiteOpenHelper { public DatabaseCreator(Context context) {

Inserting data into database:DatabaseCreator dbHelper = new DatabaseCreator(context);SQLiteDatabase db = dbHelper.getWritableDatabase();ContentValues

Fetching data from database:DatabaseCreator dbHelper = new DatabaseCreator(context);SQLiteDatabase db = dbHelper.getWritableDatabase();Cursor

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