Develop Reference

Sqlite query not showing hindi words from precreated database?

My Database Adapter Class
public class DatabaseAdapter {
// Declare a DatabaseHelper object reference
DatabaseHelper helper;
// Declare a SQLiteDatabase object reference.
SQLiteDatabase db;
// SQLiteDatabase class has methods to create, delete, execute SQL commands and perform other common database
// management tasks.
// Define an ArrayList of Term object.
ArrayList<Term> termsList = new ArrayList<Term>();
// What is Term?
// You'll create a Term class to contain and model the information and make it more easy to implement.
// Define the constructor for DatabaseAdapter
public DatabaseAdapter(Context context){
// Instantiate helper
helper = new DatabaseHelper(context);
// Call getWritableDatabase() method on helper. This is going to give you an object of SQLiteDatabase. Store that in db.
db = helper.getWritableDatabase();
// Now, this SQLiteDatabase object, db, is going to represent the database you have and you are going to use that object
// to perform the different queries that you want to do, for example, insert, update or delete from database.
}
// Define a method to close the database
public void close() {
helper.close();
}
public int deleteData(long id) {
// Define the whereArgs String array
String whereArgs[] = {""+id};
// Call delete() method on db
return db.delete(DatabaseHelper.TABLE_NAME, DatabaseHelper.KEY_ID + "=?", whereArgs);
// delete() returns the number of rows deleted as an integer.
}
public int updateTermFullForm(long id, String meaning) {
// To update the database, you need to create an object of the class called ContentValues that acts like a map, inside which you can
// put your key-value pairs.
// Here, what is expected is the name of the key that you give here is the name of the column in your table
// and the value you want to put inside the column goes in the second parameter.
ContentValues contentValues = new ContentValues();
contentValues.put(DatabaseHelper.KEY_MEANING, meaning);
// You need to create whereArgs[] array. whereArgs[] is just an array that contains the values that are substituted inside the
// question mark (?) of whereClause at run-time, when you are executing the query.
// whereArgs[] is going to contain the values for against you want to compare.
String whereArgs[] = {""+id};
// Call update() method on db
return db.update(DatabaseHelper.TABLE_NAME, contentValues, DatabaseHelper.KEY_ID + "=?", whereArgs);
// update() returns the number of rows affected as an integer.
// The plain sql statement for this can be:
// UPDATE ct SET full_form="New Value" WHERE _id=2
}
public long insertTerm(String words, String meaning) {
// Define a new ContentValues object
ContentValues contentValues = new ContentValues();
// Add term and fullForm into that
contentValues.put(DatabaseHelper.KEY_WORDS, words);
contentValues.put(DatabaseHelper.KEY_MEANING, meaning);
// Call insert() method on db object and return
return db.insert(DatabaseHelper.TABLE_NAME, null, contentValues);
}
// Next, define a method that returns an ArrayList of specific Term objects where the term starts with the String in parameter.
public ArrayList<Term> getSomeTerms(String termStartsWith){
// Call query() method on db and store the returned cursor.
Cursor cursor = db.query(DatabaseHelper.TABLE_NAME, new String[]{DatabaseHelper.KEY_ID, DatabaseHelper.KEY_WORDS,
DatabaseHelper.KEY_MEANING}, DatabaseHelper.KEY_WORDS + " like '"
+ termStartsWith + "%'",null,null,null,null);
// Here, % is a wildcard character which indicates 0 or any number of characters. So, there can be any number of characters
// after “A”, or "B" or "S" etc.
// The plain sql statement for this can be:
// SELECT * FROM ct WHERE terms LIKE 'A%';
// Use a while loop to traverse the database and populate the ArrayList of Term objects
while (cursor.moveToNext()){
// Get the database column index or position by passing the column name
int index1 = cursor.getColumnIndex(DatabaseHelper.KEY_ID);
// Now, get the value of id for that cell
long id = cursor.getInt(index1);
// Do the same thing to get values from other two columns
int index2 = cursor.getColumnIndex(DatabaseHelper.KEY_WORDS);
String words = cursor.getString(index2);
int index3 = cursor.getColumnIndex(DatabaseHelper.KEY_MEANING);
String meaning = cursor.getString(index3);
// Create a Term object from database values
Term term = new Term(id, words, meaning);
// Add the Term object to termsList
termsList.add(term);
}
// return termList
return termsList;
}
// For managing all the operations related to the database, a helper class has been provided by Android
// and it is called SQLiteOpenHelper.
// It takes care of opening the database if it exists, creating it if it does not exists, and upgrading it as necessary.
// So, inside DatabaseAdapter you'll create a static inner class that extends SQLiteOpenHelper.
private static class DatabaseHelper extends SQLiteOpenHelper{
// Define some private static final String variables to store information related to the database
private static final String DATABASE_NAME ="Test.db";
// Database name must be unique within an app, not across all the apps.
private static final String TABLE_NAME = "words";
// When you do change the structure of the database change the version number from 1 to 2
private static final int DATABASE_VERSION = 7;
static final String KEY_ID = "id";
static final String KEY_WORDS = "words";
static final String KEY_MEANING = "meaning";
private Context context;
// Define the constructor
public DatabaseHelper(Context context){
super(context, DATABASE_NAME, null, DATABASE_VERSION);
// Store the context received from constructor into this class's context variable
this.context = context;
}
// Since, you're not creating or upgrading the database since you're using a pre-created database file
// copied to the right location, you don't need to write any code inside onCreate() or onUpgrade().
#Override
public void onCreate(SQLiteDatabase db) {
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
}
My PreCreate Database Class
public class PreCreateDB {
static String destPath;
static String destPathwithFilename;
// Lets define copyDB() method
public static void copyDB(Context context){
// Defile two String variables containing path upto "database" folder and "CTDB" file respectively
destPath = "/data/data/" + context.getPackageName() + "/databases";
destPathwithFilename = destPath+"/Test.db";
// Create two File objects from those Strings
File fPath = new File(destPath);
File fPathWithName = new File(destPathwithFilename);
// Now, the question is, why we created two separate File objects?
// It's because in some devices databases folder will be automatically created by Android system.
// In some other devices it won't be there by default.
// So, we need to check if it's not present in the device.
if(!fPath.exists()){
// If true, you'll create the databases folder
fPath.mkdirs();
// And then copy the CTDB Database file from assets folder to databases folder.
// You'll define a method named rawCopy that takes an InputStream and an OutputStream.
// This method will copy the file.
try {
rawCopy(context.getAssets().open("Test.db"), new FileOutputStream(destPath+"/Test.db"));
} catch (IOException e) {
e.printStackTrace();
}
}
}
public static void rawCopy(InputStream inputStream, OutputStream outputStream) throws IOException {
// To copy 1k bytes at a time, create a byte array of size 1024
byte[] buffer = new byte[1024];
// Declare an integer variable to store the total number of bytes read from the buffer.
int length;
// If you call read() method on inputStream object and pass buffer as parameter, it will read 1024 bytes at a time.
// It returns -1 if there is no more data because the end of the stream has been reached.
// Using this information you use a while loop to read from the inputStream and write to the outputStream.
// This copies the database file CTDB from assets folder to data/data/[package-name]/databases folder.
while((length = inputStream.read(buffer)) > 0){
outputStream.write(buffer, 0, length);
}
// Close the input and output streams once you're done
inputStream.close();
outputStream.close();
}
public static void resetDB(Context context) {
// Call rawCopy() inside try block
try {
rawCopy(context.getAssets().open("Test.db"), new FileOutputStream(destPathwithFilename));
} catch (IOException e) {
e.printStackTrace();
}
}
}
MY Show Term Class
public class ShowTerm extends AppCompatActivity {
// Declare a DatabaseAdapter object reference
static DatabaseAdapter databaseAdapter;
// Declare a RecyclerView object reference
static RecyclerView rvTerms;
// Declare an Adapter object reference
TermsAdapter termsAdapter;
// Declare a LayoutManager object reference
RecyclerView.LayoutManager layoutManager;
// Define an ArrayList of type Term
static ArrayList<Term> termsList = new ArrayList<>();
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.show_term);
// Get the received String from Intent
String termStartsWith = getIntent().getStringExtra("termStartsWith");
// Instantiate DatabaseAdapter class and pass this for the Context
databaseAdapter = new DatabaseAdapter(this);
// Call getSomeTerms() on databaseAdapter object and store the returned ArrayList in
// termsList
termsList = databaseAdapter.getSomeTerms(termStartsWith);
// Obtain a handle for the RecyclerView
rvTerms = findViewById(R.id.rvTerms);
// You may use this setting to improve performance if you know that changes
// in content do not change the layout size of the RecyclerView
rvTerms.setHasFixedSize(true);
// Instantiate the linear layout manager
layoutManager = new LinearLayoutManager(this);
// Set the layout with RecyclerView
rvTerms.setLayoutManager(layoutManager);
// Create an instance of TermsAdapter. Pass context, termsList and the
// RecyclerView to the constructor
termsAdapter = new TermsAdapter(this, termsList, rvTerms);
// Finally, attach the adapter with the RecyclerView
rvTerms.setAdapter(termsAdapter);
}
}
My Bengali + Hindi Mix Sqlite Database
MainActivity Ui
This Sqlite query giving blank results for Hindi words but English words are showning Properly
My MainActivity Class
public class MainActivity extends AppCompatActivity {
// Store the text to be shared in a String
String shareBody = "Download CTD App now and know about all the important Computer Terms and their Full Forms: \n" +
"https://play.google.com/store/apps/details?id=com.sandipbhattacharya.computertermsdictionary";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Create a class containing static methods to copy the database file
// from assets folder into: data/data/package-name/databases folder, from where the app can access it.
// Lets name it PreCreateDB.
// From MainActivity, call the copyDB method of PreCreateDB and pass "this" for Context
PreCreateDB.copyDB(this);
}
public void show(View view) {
// We have set a text with every button. This text simply contains an alphabet.
// Get the clicked Button's text and store in a String variable
String termStartsWith = ((Button) view).getText().toString().trim();
// Create an Intent to go to another Activity where you can show all the Terms that start with a letter termStartsWith contains
Intent intent = new Intent(this, ShowTerm.class);
// Set termStartsWith with the Intent object as Extra
intent.putExtra("termStartsWith", termStartsWith);
// Start the Activity with the Intent
startActivity(intent);
// Create the ShowTerm class.
}
public void reset(View view) {
// You'll use Android AlertDialog to ask the user about his/her choice to continue or discontinue the reset operation.
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Resetting will delete all your personal data. Proceed?");
builder.setCancelable(true);
builder.setPositiveButton("Yes",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// Here, you call a method and pass MainActivity.this as context,
// to replace the database file from assets folder to databases folder.
PreCreateDB.resetDB(MainActivity.this);
}
});
builder.setNegativeButton("No",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
});
AlertDialog alertDialog = builder.create();
alertDialog.show();
}
public void addNew(View view) {
// You'll use an Intent to go to AddNew Activity
Intent intent = new Intent(this, AddNew.class);
startActivity(intent);
}
public void rate(View view) {
// Create an Intent that opens a URL in Google Play
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setData(Uri.parse("https://play.google.com/store/apps/details?id=" + getPackageName()));
// As you configure this intent, pass "com.android.vending" into Intent.setPackage() so that users see your app's details
// in the Google Play Store app instead of a chooser. Make sure your emulator has pre-installed Play Store app.
intent.setPackage("com.android.vending");
// Start the Activity
try {
startActivity(intent);
}catch (ActivityNotFoundException e) {
Toast.makeText(this, "Couldn't launch Play Store", Toast.LENGTH_LONG).show();
}
}
public void shareApp(View view) {
// Create a send Intent
Intent sendIntent = new Intent(Intent.ACTION_SEND);
// Set the Sharing Type
sendIntent.setType("text/plain");
// Pass your sharing content using the putExtra() method of the Intent
sendIntent.putExtra(Intent.EXTRA_SUBJECT, "Share CTD App");
sendIntent.putExtra(Intent.EXTRA_TEXT, shareBody);
// Next, instruct Android system to let the user choose their sharing medium
startActivity(Intent.createChooser(sendIntent, "Share using"));
// This will pass the sendIntent along with a title to be displayed at the top of the chooser.
// When the user chooses an application from the list, your share content will be passed to that application,
// where he/she will be able to edit the content before sending it if they wish to do so.
}
}
Please Help me because im beginner in android development and it is very important for my dictionary app 🙏

Solved the problem, in Sqlite database your table creation rules are also important when using external database.

How to create and pre-populate sqlite database file with Android Room?

I want to create the sqlite database file DatabaseName.db with few entities that should be created in path of application (/data/data/MyApplicationName/databases/DatabaseName.db) when I try to execute the snippet code bellow, however the DatabaseName.db file is not there. Why ?
MyDatabaseSample db = Room.databaseBuilder(context,
MyClass.class,
"DatabaseName.db")
.addCallback(new RoomDatabase.Callback() {
#Override
public void onCreate(#NonNull SupportSQLiteDatabase ssdb) {
super.onCreate(db);
Log.d(TAG, "Database created - populate database");
}).build();
The database is created in the path of application only if I create an instance of a entity object and insert it in database right after get the database reference db. As I want to pre-populate database just after database creation, I think just make sense do it inside onCreate method of callback, but onCreate will never be called. So, How can I create the "DatabaseName.db" file with all tables representing entities and populate the database using callback ?
OBS: I am using Room version use 1.1.0-alpha2 and compiling with SDK android API 27.

I think you need to define some Room entities before pre-populate the db that's what i have done and it works just as expected, here is some code of what i have done so far:
public class DatabaseCreator {
private static MyDatabaseSample appDatabase;
private static final Object LOCK = new Object();
public synchronized static MyDatabaseSample getDBInstance(final Context context){
if(appDatabase == null) {
synchronized (LOCK) {
if (appDatabase == null) {
RoomDatabase.Callback appDBCallback = new RoomDatabase.Callback() {
#Override
public void onCreate(#NonNull SupportSQLiteDatabase db) {
super.onCreate(db);
try {
ReadScript.insertFromFile(context, R.raw.populate_db, db);
} catch (IOException e) {
Log.d("DB Population Error", e.toString());
}
}
};
appDatabase = Room.databaseBuilder(context,
MyDatabaseSample.class, "DatabaseName").addCallback(appDBCallback).build();
}
}
}
return appDatabase;
}
}
The code above is a singleton that uses the Callback's onCreate to pre-populate the db using a "raw resource" (To add raw resources to your project just create a folder inside your res folder like this "res/raw") that contains an sql script. To read the script i have used this code:
public class ReadScript {
public static int insertFromFile(Context context, int resourceCode, SupportSQLiteDatabase db) throws IOException {
// Reseting Counter
int result = 0;
// Open the resource
InputStream insertsStream = context.getResources().openRawResource(resourceCode);
BufferedReader insertReader = new BufferedReader(new InputStreamReader(insertsStream));
// Iterate through lines (assuming each insert has its own line and theres no other stuff)
while (insertReader.ready()) {
String insertStmt = insertReader.readLine();
if(insertStmt != null){
if(insertStmt.isEmpty()) continue;
db.execSQL(insertStmt);
result++;
Log.d("Statement #", Integer.toString(result));
}
}
insertReader.close();
// returning number of inserted rows
return result;
}
}
And then you just create the db instance by doing:
MyDatabaseSample db = DatabaseCreator.getDBInstance(getContext());
Note: You can try to create tables inside the raw script but i haven't tried it yet.
Goog luck.

Checking Azure connected Database onClick for login

So Azure spit the following code for me to insert into an activity (Android Studio is what I'm using)
Add the following line to the top of the .java file containing your launcher activity:
import com.microsoft.windowsazure.mobileservices.*;
Inside your activity, add a private variable
private MobileServiceClient mClient;
Add the following code the onCreate method of the activity:
mClient = new MobileServiceClient("https://pbbingo.azurewebsites.net", this);
Add a sample item class to your project::
public class ToDoItem{ public String id; public String Text;}
In the same activity where you defined mClient, add the following code:
ToDoItem item = new ToDoItem();
item.Text = "Don't text and drive";
mClient.getTable(ToDoItem.class).insert(item, new TableOperationCallback<item>(){
public void onCompleted(ToDoItem entity, Exception exception, ServiceFilter response)
{
if(exception == null){
//Insert Succeeded
} else {
//Insert Failed
}
}});
My goal is to create a login page. I understand that the above was probably offered up more with a ToList in mind. I just want to get the syntax correct today. The problem I think, is my basic class structure. I have created an OnClick Listener within my on create that gets the ID from a button in my layout. I don't need it checking for anything in the database until the button has been actually clicked to either login or register.
public class LoginClass extends AppCompatActivity{
public void onCreate(Bundle savedInstanceState) {
setContentView(R.layout.MyLoginLayout);
MobileServiceClient mClient = null;
try {
mClient = new MobileServiceClient ("myAzureWebsite", "AzureKey", this);
} catch (MalformedURLException e) {
e.printStackTrace();
}
Button Attempt = (Button) findViewById (R.id.mySubmitButton);
final MobileServiceClient finalMClient = mClient; // finalized so I can use it later.
Attempt.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick (View v) {
final View thisView = v;
final MyToDoItemClass item = new MyToDoItemClass();
In MyToDoItemClass I have two variables (Both String) Just left over from
the example of a ToDoList (they are String ID and String Text)
item.Text = "Filler";
item.ID = "Fill";
finalMClient.getTable(MyToDoItemClass.class).insert(new Table OperationCallback<item>() { //<--- I'm getting an error that the variable, item
is from an unknown class...
public void onCompleted (Item entity, Exception exception, ServiceFilterResponse response){
if(exception == null) {
Intent i = new Intent (LoginClass.this, MainActivity.class);
startActivity(i);
}else{
Toast.makeText(thisView.getContext(), "Failed", Toast.LENGTH_LONG).show();
}}
});
}
});
}}
The problem is with that the TableOperationCallback is saying that the item from MyToDoItemClass class is from an unknown class.

There are many issues in your code, as below.
According to the javadoc for class MobileServiceClient, there is not a method insert(TableOperationCallback<E> callback), so the code finalMClient.getTable(MyToDoItemClass.class).insert(new Table OperationCallback<item>() {...} is invalid.
The generics E in Table OperationCallback<E> means that you need to write a POJO class name instead of E, not an object variable name like item, so the correct code should be new Table OperationCallback<MyToDoItemClass>, please see the Oracle tutorial for Generics to know more details.
The figure below shows all methods insert of class MobileServiceClient. The bold word Deprecated under the method name means that you should not use it for developing on new project, it‘s only compatible for old project on the new version of Java SDK.
Please follow the offical tutorial to develop your app. Any concern, please feel free to let me know.

Inserting data, "MobileServiceTable must have a single id property defined"

I'm currently developing an android app that requires data to be inserted into an azure Mobile Service DB. An id string and a first login integer, to be exact. However the following error is being thrown up.
"IllegalArgumentException: The class representing the MobileServiceTable must have a single id property defined"
The id value that I need to insert into the database is being passed back from a fragment interface using passId(). Inside the override of this is where I am attempting to insert the values into azure as shown below.
#Override
public void passId(String id) {
userInstance user = new userInstance();
user.user_id = id;
user.first_login = 0;
mClient.getTable(userInstance.class).insert(user, new TableOperationCallback<userInstance>() {
public void onCompleted(userInstance entity, Exception exception, ServiceFilterResponse response) {
if (exception == null) {
// Insert succeeded
} else {
// Insert failed
}
}
});
The mClient var represents the MobileServicesClient as shown below
try {
mClient = new MobileServiceClient(
"https://xxxx.azure-mobile.net/",
"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
this);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (Exception e){
e.printStackTrace();
}
The table name that I am trying to insert the data into is "user_table" if that helps at all.
I hope you're able to help, and thanks in advance for any help you guys give me.

SOLUTION:
Because the Azure Table that I was attempting to add data to auto created an "id" column, the user object that I was using to construct user info to insert into the database had to define an "id" String. As shown below:
public class userInstance {
#com.google.gson.annotations.SerializedName("id")
public String mId;
#com.google.gson.annotations.SerializedName("user_id")
public String mUserId;
#com.google.gson.annotations.SerializedName("first_login")
public int mLogin;
}

Creating a separate method to read in text files from a subfolder in the assets folder

This is my first time on here, so I'm bit nervous and please forgive me if I don't seem entirely clear about what I'm asking.
The problem is, Im trying to read in a file from a subfolder in the assets folder, using a method that I've created in a separate class. I've researched this for a couple of days but I'm unable to find the solution anywhere, so I've come here as a last resort. I needed the file reading method to be separate as there are other views/activities that will be utilising exactly the same method and I don't think it would be wise to keep copying and pasting the same code for each activity. Ok here's what I've done so far:
public class ReadAssets extends Activity {
public void read(Context context, String filepath, int textviewid) {
try {
InputStream input = getAssets().open(filepath);
int size = input.available();
// Read the entire asset into a local byte buffer.
byte[] buffer = new byte[size];
input.read(buffer);
input.close();
// Convert the buffer into a string.
String text = new String(buffer);
// Finally insert the string into the text view.
TextView tv = (TextView) findViewById(textviewid);
tv.setText(text);
} catch (IOException e) {
// Throws an exception if an error is found
throw new RuntimeException(e);
}
}
}
The activity that I would like to place this method in:
public class GeneralSetupActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.gettingstarted_layout);
ReadAssets nA = new ReadAssets();
nA.read(this,"gettingstarted/GettingStarted.txt", R.id.displayTextView);
// try {
// InputStream input =getAssets().open("gettingstarted/GettingStarted.txt");
//
// int size = input.available();
//
// // Read the entire asset into a local byte buffer.
// byte[] buffer = new byte[size];
// input.read(buffer);
// input.close();
//
// // Convert the buffer into a string.
// String text = new String(buffer);
//
// // Finally insert the string into the text view.
// TextView tv = (TextView) findViewById(R.id.displayTextView);
// tv.setText(text);
//
// } catch (IOException e) {
// // Throws an exception if an error is found
// throw new RuntimeException(e);
// }
}
}
I'd really appreciate it file someone could point me towards the right direction. And also I hope I'm not taking advantage but I'd like to know how I'd import and display a series of text files, one after another.
Cheers Guys,
Thanks :)

If you need this available to all different types of Activity, you should consider putting the method in a superclass so all the children can use it.
public class ExtraFunctionalActivity extends Activity
{
public void read(...)
{
//your code
}
}
public class GeneralSetupUtility extends ExtraFunctionalActivity
{
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.gettingstarted_layout);
read(this,"gettingstarted/GettingStarted.txt", R.id.displayTextView);
}
}
Otherwise, if this method is needed by a bunch of unrelated classes, you could put it in a utility class;
public class FileUtil
{
public static void read(...)
{
//your code
}
}
then you can call it where needed with
FileUtil.read(args here);

You may have a class like Fileparsingutility with the method you want to separate. You may define Inputstream as parameter(you may pass other required things as parameter for that method). What ever actvity you want to use this method, instantiate above class and invoke the method by passing parameters.
Fileparinsgutility util=new Fileparsingutility();
Returnobj retObj =util.parse(......);