public class SharedPreferencesExample extends Activity {
private static final String MY_DB = "my_db";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// INSTANTIATE SHARED PREFERENCES CLASS
SharedPreferences sp = getSharedPreferences(MY_DB,
Context.MODE_PRIVATE);
// LOAD THE EDITOR REMEMBER TO COMMIT CHANGES!
Editor e = sp.edit();
e.putString("strKey", "Hello World");
e.putBoolean("boolKey", true);
e.commit();
String stringValue = sp.getString("strKey", "error");
boolean booleanValue = sp.getBoolean("boolKey", false);
Log.i("LOG_TAG", "String value: " + stringValue);
Log.i("LOG_TAG ", "Boolean value: " + booleanValue);
}
}

getSharedPreferences(String mapName, int mapMode)

String stringValue = sp.getString("strKey", "error");
boolean booleanValue = sp.getBoolean("boolKey", false);

public class SharedPreferencesExample2 extends Activity {
private static final String MY_DB = "my_db";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
SharedPreferences sp = getSharedPreferences(MY_DB,
Context.MODE_PRIVATE);
/**
* CHECK IF THIS IS USER'S FIRST VISIT
*/
boolean hasVisited = sp.getBoolean("hasVisited",
false);
if (!hasVisited) {
// ...
// SHOW SPLASH ACTIVITY, LOGIN ACTIVITY, ETC
// ...
// DON'T FORGET TO COMMIT THE CHANGE!
Editor e = sp.edit();
e.putBoolean("hasVisited", true);
e.commit();
}
}
}

/**
* CHECK LAST UPDATE TIME
*/
long lastUpdateTime = sp.getLong("lastUpdateKey", 0L);
long timeElapsed = System.currentTimeMillis() -
lastUpdateTime;
// YOUR UPDATE FREQUENCY HERE
final long UPDATE_FREQ = 1000 * 60 * 60 * 24;
if (timeElapsed > UPDATE_FREQ) {
// ...
// PERFORM NECESSARY UPDATES
// ...
}
// STORE LATEST UPDATE TIME
Editor e = sp.edit();
e.putLong("lastUpdateKey", System.currentTimeMillis());
e.commit();

/**
* CACHE USER NAME AS STRING
*/
// TYPICALLY YOU WILL HAVE AN EDIT TEXT VIEW
// WHERE THE USER ENTERS THEIR USERNAME
EditText userNameLoginText = (EditText)
findViewById(R.id.login_editText);
String userName =
userNameLoginText.getText().toString();
Editor e = sp.edit();
e.putString("userNameCache", userName);
e.commit();

/**
* REMEBERING A CERTAIN STATE
*/
boolean isSilentMode = sp.getBoolean("isSilentRinger",
false);
if (isSilentMode) {
// ...
// TURN OFF APPLICATION
// ...
}

/**
* CACHING A LOCATION
*/
// INSTANTIATE LOCATION MANAGER
LocationManager locationManager = (LocationManager)
this.getSystemService(Context.LOCATION_SERVICE);
// ...
// IGNORE LOCATION LISTENERS FOR NOW
// ...
Location lastKnownLocation =
locationManager.getLastKnownLocation
(LocationManager.NETWORK_PROVIDER);
float lat = (float) lastKnownLocation.getLatitude();
float lon = (float) lastKnownLocation.getLongitude();
Editor e = sp.edit();
e.putFloat("latitudeCache", lat);
e.putFloat("longitudeCache", lon);
e.commit();

Set<String> values = new HashSet<String>();
values.add("Hello");
values.add("World");
Editor e = sp.edit();
e.putStringSet("strSetKey", values);
e.commit();
Set<String> ret = sp.getStringSet(values, new HashSet<String>());
for(String r : ret) {
Log.i("SharedPreferencesExample", "Retrieved vals: " + r);
}

public class InternalStorageExample extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// THE NAME OF THE FILE
String fileName = "my_file.txt";
// STRING TO BE WRITTEN TO FILE
String msg = "Hello World.";
try {
// CREATE THE FILE AND WRITE
FileOutputStream fos = openFileOutput(fileName,
Context.MODE_PRIVATE);
fos.write(msg.getBytes());
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

public class InternalStorageExample2 extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// THE NAME OF THE FILE
String fileName = "my_file.txt";
try {
// OPEN FILE INPUT STREAM THIS TIME
FileInputStream fis = openFileInput(fileName);
InputStreamReader isr = new InputStreamReader(fis);
// READ STRING OF UNKNOWN LENGTH
StringBuilder sb = new StringBuilder();
char[] inputBuffer = new char[2048];
int l;
// FILL BUFFER WITH DATA
while ((l = isr.read(inputBuffer)) != -1) {
sb.append(inputBuffer, 0, l);
}
// CONVERT BYTES TO STRING
String readString = sb.toString();
Log.i("LOG_TAG", "Read string: " + readString);
// CAN ALSO DELETE THE FILE
deleteFile(fileName);
} catch (IOException e) {
e.printStackTrace();
}
}
}

public class ExternalStorageExample extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
String fileName = "my_file.txt";
String msg = "Hello World.";
boolean externalAvailable = false;
boolean externalWriteable = false;
String state = Environment.getExternalStorageState();
if (state.equals(Environment.MEDIA_MOUNTED)) {
// HERE MEDIA IS BOTH AVAILABLE AND WRITEABLE
externalAvailable = true;
externalWriteable = true;
} else if
(state.equals(Environment.MEDIA_MOUNTED_READ_ONLY)) {
// HERE SD CARD IS AVAILABLE BUT NOT WRITEABLE
externalAvailable = true;
} else {
// HERE FAILURE COULD BE RESULT OF MANY SITUATIONS
// NO OP
external storage methodsabout}
if (externalAvailable && externalWriteable) {
// FOR API LEVEL 7 AND BELOW
// RETRIEVE SD CARD DIRECTORY
File r = Environment.getExternalStorageDirectory();
File f = new File(r, fileName);
try {
// NOTE DIFFERENT FROM INTERNAL STORAGE WRITER
FileWriter fWriter = new FileWriter(f);
BufferedWriter out = new BufferedWriter(fWriter);
out.write(msg);
out.close();
} catch (IOException e) {
e.printStackTrace();
}
} else {
Log.e("LOG_TAG", "SD CARD UNAVAILABLE");
}
}
}

getExternalFilesDir(String type)
getExternalStoragePublicDirectory(String type)

DIRECTORY_ALARMS
DIRECTORY_DCIM
DIRECTORY_DOWNLOADS
DIRECTORY_MOVIES
DIRECTORY_MUSIC
DIRECTORY_NOTIFICATIONS
DIRECTORY_PICTURES
DIRECTORY_PODCASTS
DIRECTORY_RINGTONES

public class SQLiteHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "my_database.db";
// TOGGLE THIS NUMBER FOR UPDATING TABLES AND DATABASE
private static final int DATABASE_VERSION = 1;
// NAME OF TABLE YOU WISH TO CREATE
public static final String TABLE_NAME = "my_table";
// SOME SAMPLE FIELDS
public static final String UID = "_id";
public static final String NAME = "name";
SQLiteHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE " + TABLE_NAME + " (" + UID + "
INTEGER PRIMARY KEY AUTOINCREMENT," + NAME
+ " VARCHAR(255));");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion,
int newVersion) {
Log.w("LOG_TAG", "Upgrading database from version " +
oldVersion + " to " + newVersion + ",
which will destroy all old data");
// KILL PREVIOUS TABLE IF UPGRADED
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
// CREATE NEW INSTANCE OF TABLE
onCreate(db);
}
}

CREATE TABLE my_table (_id INTEGER PRIMARY KEY AUTOINCREMENT,
name VARCHAR(255));

public class SQLiteExample extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// INIT OUR SQLITE HELPER
SQLiteHelper sqh = new SQLiteHelper(this);
// RETRIEVE A READABLE AND WRITEABLE DATABASE
SQLiteDatabase sqdb = sqh.getWritableDatabase();
// METHOD #1: INSERT USING CONTENTVALUE CLASS
ContentValues cv = new ContentValues();
cv.put(SQLiteHelper.NAME, "jason wei");
// CALL INSERT METHOD
sqdb.insert(SQLiteHelper.TABLE_NAME, SQLiteHelper.NAME,
cv);
// METHOD #2: INSERT USING SQL QUERY
String insertQuery = "INSERT INTO " +
SQLiteHelper.TABLE_NAME +
" (" + SQLiteHelper.NAME + ") VALUES ('jwei')";
sqdb.execSQL(insertQuery);
// METHOD #1: QUERY USING WRAPPER METHOD
Cursor c = sqdb.query(SQLiteHelper.TABLE_NAME,
new String[] { SQLiteHelper.UID, SQLiteHelper.NAME },
null, null, null, null, null);
while (c.moveToNext()) {
// GET COLUMN INDICES + VALUES OF THOSE COLUMNS
int id = c.getInt(c.getColumnIndex(SQLiteHelper.UID));
String name =
c.getString(c.getColumnIndex(SQLiteHelper.NAME));
Log.i("LOG_TAG", "ROW " + id + " HAS NAME " + name);
}
c.close();
// METHOD #2: QUERY USING SQL SELECT QUERY
String query = "SELECT " + SQLiteHelper.UID + ", " +
SQLiteHelper.NAME + " FROM " + SQLiteHelper.TABLE_NAME;
Cursor c2 = sqdb.rawQuery(query, null);
while (c2.moveToNext()) {
int id =
c2.getInt(c2.getColumnIndex(SQLiteHelper.UID));
String name =
c2.getString(c2.getColumnIndex(SQLiteHelper.NAME));
Log.i("LOG_TAG", "ROW " + id + " HAS NAME " + name);
}
c2.close();
// CLOSE DATABASE CONNECTIONS
sqdb.close();
sqh.close();
}
}

while (c.moveToNext()) {
// GET COLUMN INDICES + VALUES OF THOSE COLUMNS
int id = c.getInt(c.getColumnIndex(SQLiteHelper.UID));
String name = c.getString(c.getColumnIndex(SQLiteHelper.NAME));
Log.i("LOG_TAG", "ROW " + id + " HAS NAME " + name);
}