Close() was never explicitly called on database even after implementing close()

Question

Eclipse is showing me the above error even though I have implemented the said methos close().

Here is the code:

public void update_project(View view) {

    EditText cinone = (EditText) findViewById(R.id.pname);
    pname = cinone.getText().toString();

    String fDate = pday + ". " + pmonth + ". " + pyear;

    projectdatabase dbupdate = new projectdatabase(UpdateProject.this);

    dbupdate.open();
    dbupdate.updateProject(id, pname, fDate); 
    dbupdate.close();

}

Logcat:

12-31 22:05:51.114: E/SQLiteDatabase(4180): close() was never explicitly called on  
database '/data/data/com.kk.project/databases/project_db' 
12-31 22:05:51.114: E/SQLiteDatabase(4180):  
android.database.sqlite.DatabaseObjectNotClosedException: Application did not close the     
cursor or database object that was opened here
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at  
android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1943)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at 
android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:1007)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at   
android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:986)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at 
android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:1051)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at 
android.app.ContextImpl.openOrCreateDatabase(ContextImpl.java:770)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at  
android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:221)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at 
android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:157)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at     
com.kk.project.projectdatabase.open(projectdatabase.java:66)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at  
com.kk.project.ProjectExplorer.getinfo(ProjectExplorer.java:30)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at    
com.kk.project.ProjectExplorer.onCreate(ProjectExplorer.java:25)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at  
android.app.Activity.performCreate(Activity.java:4465)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at  
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at 
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at 
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at  
android.app.ActivityThread.access$600(ActivityThread.java:123)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at 
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at  
android.os.Handler.dispatchMessage(Handler.java:99)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at 
android.os.Looper.loop(Looper.java:137)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at  
android.app.ActivityThread.main(ActivityThread.java:4424)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at   
java.lang.reflect.Method.invokeNative(Native Method)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at     
java.lang.reflect.Method.invoke(Method.java:511)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at 
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at   
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
12-31 22:05:51.114: E/SQLiteDatabase(4180):     at 
dalvik.system.NativeStart.main(Native Method)
12-31 22:05:51.165: E/System(4180): Uncaught exception thrown by finalizer
12-31 22:05:51.174: D/dalvikvm(4180): GREF has increased to 201
12-31 22:05:51.204: I/dalvikvm(4180): threadid=3: reacting to signal 3
12-31 22:05:51.324: E/System(4180): java.lang.IllegalStateException: Don't have   
database lock!
12-31 22:05:51.324: E/System(4180):     at  
android.database.sqlite.SQLiteDatabase.verifyLockOwner(SQLiteDatabase.java:2090)
12-31 22:05:51.324: E/System(4180):     at  
android.database.sqlite.SQLiteDatabase$1.entryRemoved(SQLiteDatabase.java:2182)
12-31 22:05:51.324: E/System(4180):     at   
android.database.sqlite.SQLiteDatabase$1.entryRemoved(SQLiteDatabase.java:2178)
12-31 22:05:51.324: E/System(4180):     at  
android.util.LruCache.trimToSize(LruCache.java:197)
12-31 22:05:51.324: E/System(4180):     at   
android.util.LruCache.evictAll(LruCache.java:285)
12-31 22:05:51.324: E/System(4180):     at   
android.database.sqlite.SQLiteDatabase.deallocCachedSqlStatements  
(SQLiteDatabase.java:2143)
12-31 22:05:51.324: E/System(4180):     at  
android.database.sqlite.SQLiteDatabase.closeClosable(SQLiteDatabase.java:1126)
12-31 22:05:51.324: E/System(4180):     at  
android.database.sqlite.SQLiteDatabase.finalize(SQLiteDatabase.java:1914)
12-31 22:05:51.324: E/System(4180):     at   
java.lang.Daemons$FinalizerDaemon.doFinalize(Daemons.java:182)
12-31 22:05:51.324: E/System(4180):     at  
java.lang.Daemons$FinalizerDaemon.run(Daemons.java:168)
12-31 22:05:51.324: E/System(4180):     at java.lang.Thread.run(Thread.java:856)

The strange thing is that I have used similar code preciously and it worked flawlessly. Also, Other methods from the same database class works perfectly.

Code of the activity which calls the updateProject:

public class UpdateProject extends Activity implements OnItemSelectedListener,  DatePickerDialog.OnDateSetListener {

int mPos;
String mSelection;

String pname;
String pdifficulty;

int pday;
int pmonth;
int pyear;

String id;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_update_project);

    id = getIntent().getExtras().getString("idforupdate");

    userdatabase viewname = new userdatabase(this);             //Get username
    viewname.open();
    String name = viewname.getusername();
    viewname.close();

    if(name.equals("")) {

        DialogFragment newFragment = new NouserexitFragment();
        newFragment.show(getFragmentManager(), "exit");

    }

    Spinner spinner = (Spinner) findViewById(R.id.difficultyspinner); ArrayAdapter<CharSequence> 
    adapter = ArrayAdapter.createFromResource(this,R.array.difficultyarray, android.R.layout.simple_spinner_item);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner.setAdapter(adapter);
    spinner.setOnItemSelectedListener(this);

    pdifficulty = spinner.getSelectedItem().toString();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.activity_update_project, menu);
    return true;
}

@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public void datepicker(View v) {                                                        //Date picker   
    DialogFragment newFragment = new DatePickerForUpdate();
    newFragment.show(getFragmentManager(), "datePickerforupdate");

}


    @Override
public void onDateSet(DatePicker view, int year, int month, int day) {
    // TODO Auto-generated method stub

    pday = day;
    pmonth = month +1;
    pyear = year;

    month = month + 1;
    Button activityButton = (Button)findViewById(R.id.datebutton);
    activityButton.setText (day + "." + month + "." + year);

}

@Override
public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
    // TODO Auto-generated method stub

    UpdateProject.this.mPos = pos;
    UpdateProject.this.mSelection = parent.getItemAtPosition(pos).toString();

}

@Override
public void onNothingSelected(AdapterView<?> arg0) {
    // TODO Auto-generated method stub

}

public void update_project(View view) {

EditText cinone = (EditText) findViewById(R.id.pname);
pname = cinone.getText().toString();

String fdate = pday + ". " + pmonth + ". " + pyear;

projectdatabase update = new projectdatabase(UpdateProject.this);
update.open();
update.updateProject(id, pname, fdate);
update.close();


}

}

Code for database class:

public class projectdatabase {

public static final String KEY_ROWID = "_id";
public static final String PROJECT_NAME = "project_name";
public static final String PROJECT_ID = "project_id";
public static final String PROJECT_DIFFICULTY = "project_difficulty";
public static final String PROJECT_STATUS = "project_status";
public static final String PROJECT_START_DATE = "project_start_date";
public static final String PROJECT_FINISH_DATE = "project_finsish_date";

private static final String DATABASE_NAME = "project_db";
static final String DATABASE_TABLE = "project_details";
private static final int DATABASE_VERSION = 1;

private DbHelper ourHelper;
private final Context projectdbContext;
private SQLiteDatabase projectDatabase;

private static class DbHelper extends SQLiteOpenHelper {
    public DbHelper(Context context) {

        super(context, DATABASE_NAME, null, DATABASE_VERSION);

    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub

        db.execSQL("CREATE TABLE "+ DATABASE_TABLE + " (" +
                KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                PROJECT_NAME + " TEXT NOT NULL, " +
                PROJECT_ID + " INTEGER, " +
                PROJECT_START_DATE + " TEXT, " +
                PROJECT_FINISH_DATE + " TEXT, " +
                PROJECT_DIFFICULTY + " TEXT, " +
                PROJECT_STATUS + " TEXT);"
               ); 

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub

        db.execSQL("DROP TABLE IF EXIST " + DATABASE_NAME);
        onCreate(db);

    }
}

public projectdatabase (Context c) {                            
     projectdbContext = c;
}

public projectdatabase open() {                                                 //Open database
    ourHelper = new DbHelper(projectdbContext);
    projectDatabase = ourHelper.getWritableDatabase();
    return this;
}

public void close() {                                                           //Close database
    ourHelper.close();
}

public long createEntry(String name, String pid, String startdate, String finishdate, String difficulty, String Status) {           //Enter project data into database

    ContentValues cv = new ContentValues();
    cv.put(PROJECT_NAME, name);
    cv.put(PROJECT_ID, pid);
    cv.put(PROJECT_START_DATE, startdate);
    cv.put(PROJECT_FINISH_DATE, finishdate);
    cv.put(PROJECT_DIFFICULTY, difficulty);
    cv.put(PROJECT_STATUS, Status);

    return projectDatabase.insert(DATABASE_TABLE, null, cv);
}

public String getData() {                                                       //Retrieve all project data

    String[] columns = new String[] {KEY_ROWID, PROJECT_NAME, PROJECT_ID, PROJECT_START_DATE, PROJECT_FINISH_DATE, PROJECT_DIFFICULTY, PROJECT_STATUS};
    Cursor c = projectDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
    String result = "";

    int iRow = c.getColumnIndex(KEY_ROWID);
    int iName = c.getColumnIndex(PROJECT_NAME);
    int iID = c.getColumnIndex(PROJECT_ID);
    int iStartDate = c.getColumnIndex(PROJECT_START_DATE);
    int iFinishDate = c.getColumnIndex(PROJECT_FINISH_DATE);
    int iDifficulty = c.getColumnIndex(PROJECT_DIFFICULTY);
    int iStatus = c.getColumnIndex(PROJECT_STATUS);

    for(c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {

        result = result + c.getString(iRow) + "|" + c.getString(iName) + "|" + c.getString(iID) + "|" + c.getString(iStartDate) + "|" + c.getString(iFinishDate) + "|" + c.getString(iDifficulty) + "|" + c.getString(iStatus) + "\n";

    }

    return result;
}

public Cursor getDataforDisplay () {                                            //Project data for list view

    String[] columns = new String[] {KEY_ROWID, PROJECT_NAME, PROJECT_FINISH_DATE, PROJECT_DIFFICULTY, PROJECT_STATUS};
    Cursor c = projectDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);

    c.moveToFirst();
    return c;

}

public String getProjectName(String id) {                   

    String[] columns = new String[] {PROJECT_NAME,KEY_ROWID};
    Cursor c = projectDatabase.query(DATABASE_TABLE, columns, KEY_ROWID + "=" + id, null, null, null, null);

    if(c != null) {

        int iName = c.getColumnIndex(PROJECT_NAME);

        c.moveToFirst();
        String name = c.getString(iName);
        return name;

    }

    return null;
}

public String getProjectStatus(String id) {

    String[] columns = new String[] {PROJECT_STATUS,KEY_ROWID};
    Cursor c = projectDatabase.query(DATABASE_TABLE, columns, KEY_ROWID + "=" + id, null, null, null, null);

    if(c != null) {

        int iStatus = c.getColumnIndex(PROJECT_STATUS);

        c.moveToFirst();
        String status = c.getString(iStatus);
        return status;

    }

    return null;
}

public String getProjectDifficulty(String id) {

String[] columns = new String[] {PROJECT_DIFFICULTY,KEY_ROWID};
Cursor c = projectDatabase.query(DATABASE_TABLE, columns, KEY_ROWID + "=" + id, null, null, null, null);

if(c != null) {

    int iDiff = c.getColumnIndex(PROJECT_DIFFICULTY);

    c.moveToFirst();
    String diff = c.getString(iDiff);
    return diff;

}

return null;

}

public String getProjectstartdate(String id) {

String[] columns = new String[] {PROJECT_START_DATE,KEY_ROWID};
Cursor c = projectDatabase.query(DATABASE_TABLE, columns, KEY_ROWID + "=" + id, null, null, null, null);

if(c != null) {

    int iSdate = c.getColumnIndex(PROJECT_START_DATE);

    c.moveToFirst();
    String sdate = c.getString(iSdate);
    return sdate;

}

return null;

}

public String getProjectfinishdate(String id) {

String[] columns = new String[] {PROJECT_FINISH_DATE,KEY_ROWID};
Cursor c = projectDatabase.query(DATABASE_TABLE, columns, KEY_ROWID + "=" + id, null, null, null, null);

if(c != null) {

    int iFdate = c.getColumnIndex(PROJECT_FINISH_DATE);

    c.moveToFirst();
    String fdate = c.getString(iFdate);
    return fdate;

}

return null;

}

public void updateProject(String id, String PName, String FDate) { //method to update the database

ContentValues cvUpdate = new ContentValues();
cvUpdate.put(PROJECT_NAME, PName);
cvUpdate.put(PROJECT_FINISH_DATE, FDate);

projectDatabase.update(DATABASE_TABLE, cvUpdate, KEY_ROWID + "=" + id, null); 

}

}

EDIT: If I replace updateProject() method with any other method from the database class, the error vanishes and the app runs with no problem.

Answer 1

You need to design your SQLiteOpenHelper class correctly. Many gurus suggest to make a static reference which will ensure that there exists only one DatabaseHelper instance at any time.

Below code will give you some idea about it. (This is not a complete code but will give you a some hint)

public class DatabaseHelper extends SQLiteOpenHelper { 
    private static DatabaseHelper mDBHelper;

    public static DatabaseHelper getInstance(Context ctx) {

        if (mDBHelper == null) { //this will ensure no multiple instances out there.
            mDBHelper = new DatabaseHelper(ctx.getApplicationContext());
        }
        return mDBHelper;
    }

}

Now, do a trick.

open the database

private SQLiteDatabase db;
    public synchronized SQLiteDatabase open() throws SQLException {

        if(db ==null){
            db = DBHelper.getWritableDatabase();
        }

        return db;
    }

Close the database.

public synchronized void close() {

        //do nothing. This is a trick.
    }

Reason : For mobile application, there is no need of open and close mechanism. It is best suitable for the Web application where multiple users are trying to access db but in the case of mobile application, only single user is going to use your application.

This hack will also make sure that you will never ever get the Close() was never explicitly called on database error. This exception is thrown when you have opened more SQLiteDatabase instances than you have closed and now in our case there is only one SQLiteDatabse instance. This will also handle the concurrent db access/write problem.

Hope this hack will help you to understand the actual problem.

For better understanding, you can refer this link.

Answer 2

public projectdatabase open() {
    ourHelper = new DbHelper(projectdbContext);
    projectDatabase = ourHelper.getWritableDatabase();
    return this;
}

public void close() {
    ourHelper.close();
}

Up there, try changing ourHelper.close() to projectDatabase.close(). You have to close the instance of the SQLiteDatabase's WriteableDatabase that you opened. Not the DBHelper.

So your close function would become:

public void close() {
    projectDatabase.close();
}

[EDIT]: From the sqlite website I found this info. The reason it works when you replace updateProject() with any other method is because that is the only method in which you obtain a write lock on the database. SQLite databases have no read lock, only a write lock.

Have you tried calling a close on the projectDatabase at the end of your updateProject() method (inside it)?

Another suggestion I would make is to make your Database class a singleton. This would avoid any conflicts as there'd be just one object accessing the db at any given time.