Accessing the external already created database.But the Code isnt working

Question

This is the Main Activity that i have written and it is not working ! Please Help

import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {
Button button1;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    button1.findViewById(R.id.button1);
    button1.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub 
            Toast.makeText(getApplicationContext(),"onClick aaaayaaaa", Toast.LENGTH_LONG).show();

            try {
                MyDatabase db=new MyDatabase(MainActivity.this);
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    });



    }



}

This is the MyDatabase java file that I wrote to access the external database which is pre-populated using different application

import android.database.sqlite.SQLiteException;
import android.widget.Toast;

import com.readystatesoftware.sqliteasset.SQLiteAssetHelper;

public class MyDatabase extends SQLiteAssetHelper {
 private Context mycontext;
    private String DB_PATH="/mnt/sdcard/Kitchen_Data.db"; 

    private static String DB_NAME = "Kitchen_Data.db";
    public SQLiteDatabase myDataBase;


    public MyDatabase(Context context) throws IOException  {

        super(context,DB_NAME,null,1);
        this.mycontext=context;
        Toast.makeText(mycontext, "Constructor called", Toast.LENGTH_LONG).show();

        boolean dbexist = checkdatabase();
        if (dbexist) {
              opendatabase(); 
        } else {
            System.out.println("Database doesn't exist");
            createdatabase();
        }
    }

    public void createdatabase() throws IOException {
        boolean dbexist = checkdatabase();
        if(!dbexist) {
            this.getReadableDatabase();
            try {
                copydatabase();
            } catch(IOException e) {
                throw new Error("Error copying database");
            }
        }
    }   

    private boolean checkdatabase() {

        boolean checkdb = false;
        try {
            String myPath = DB_PATH;
            File dbfile = new File(myPath);
            Toast.makeText(mycontext, "Database exists", Toast.LENGTH_LONG).show();
            checkdb = dbfile.exists();
        } catch(SQLiteException e) {Toast.makeText(mycontext, "Error in database", Toast.LENGTH_LONG).show();
        }
        return checkdb;
    }

    private void copydatabase() throws IOException {
        //Open your local db as the input stream
        InputStream myinput = mycontext.getAssets().open(DB_NAME);

        // Path to the just created empty db
        String outfilename = DB_PATH;

        //Open the empty db as the output stream
        OutputStream myoutput = new FileOutputStream(outfilename);

        // transfer byte to inputfile to outputfile
        byte[] buffer = new byte[1024];
        int length;
        while ((length = myinput.read(buffer))>0) {
            myoutput.write(buffer,0,length);
        }

        //Close the streams
        myoutput.flush();
        myoutput.close();
        myinput.close();
    }

    public void opendatabase() throws SQLException {
        //Open the database
        String mypath = DB_PATH;
        myDataBase = SQLiteDatabase.openDatabase(mypath, null, SQLiteDatabase.OPEN_READWRITE);
        Toast.makeText(mycontext, "database opeened", Toast.LENGTH_LONG).show();
    }

    public synchronized void close() {
        if(myDataBase != null) {
            myDataBase.close();
        }
        super.close();
    }

}

Here's the logcat:

03-31 12:34:37.045: D/AndroidRuntime(15922): Shutting down VM
03-31 12:34:37.045: W/dalvikvm(15922): threadid=1: thread exiting with uncaught exception (group=0x40d79ae0)
03-31 12:34:37.055: E/AndroidRuntime(15922): FATAL EXCEPTION: main
03-31 12:34:37.055: E/AndroidRuntime(15922): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.kitchen_application/com.example.kitchen_application.MainActivity}: java.lang.NullPointerException
 03-31 12:34:37.055: E/AndroidRuntime(15922):   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2186)
 03-31 12:34:37.055: E/AndroidRuntime(15922):   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2236)
 03-31 12:34:37.055: E/AndroidRuntime(15922):   at android.app.ActivityThread.access$600(ActivityThread.java:145)
 03-31 12:34:37.055: E/AndroidRuntime(15922):   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1238)
 03-31 12:34:37.055: E/AndroidRuntime(15922):   at android.os.Handler.dispatchMessage(Handler.java:99)
 03-31 12:34:37.055: E/AndroidRuntime(15922):   at android.os.Looper.loop(Looper.java:137)
 03-31 12:34:37.055: E/AndroidRuntime(15922):   at android.app.ActivityThread.main(ActivityThread.java:5099)
 03-31 12:34:37.055: E/AndroidRuntime(15922):   at java.lang.reflect.Method.invokeNative(Native Method)
 03-31 12:34:37.055: E/AndroidRuntime(15922):   at java.lang.reflect.Method.invoke(Method.java:511)
 03-31 12:34:37.055: E/AndroidRuntime(15922):   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:803)
 03-31 12:34:37.055: E/AndroidRuntime(15922):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:570)
 03-31 12:34:37.055: E/AndroidRuntime(15922):   at dalvik.system.NativeStart.main(Native Method)
03-31 12:34:37.055: E/AndroidRuntime(15922): Caused by: java.lang.NullPointerException
03-31 12:34:37.055: E/AndroidRuntime(15922):    at com.example.kitchen_application.MainActivity.onCreate(MainActivity.java:30)
03-31 12:34:37.055: E/AndroidRuntime(15922):    at android.app.Activity.performCreate(Activity.java:5117)
03-31 12:34:37.055: E/AndroidRuntime(15922):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)
03-31 12:34:37.055: E/AndroidRuntime(15922):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2150)
03-31 12:34:37.055: E/AndroidRuntime(15922):    ... 11 more
03-31 12:35:38.650: D/AndroidRuntime(16560): Shutting down VM
03-31 12:35:38.650: W/dalvikvm(16560): threadid=1: thread exiting with uncaught exception (group=0x40d79ae0)
03-31 12:35:38.660: E/AndroidRuntime(16560): FATAL EXCEPTION: main
03-31 12:35:38.660: E/AndroidRuntime(16560): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.kitchen_application/com.example.kitchen_application.MainActivity}: java.lang.NullPointerException
03-31 12:35:38.660: E/AndroidRuntime(16560):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2186)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2236)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at android.app.ActivityThread.access$600(ActivityThread.java:145)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1238)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at android.os.Handler.dispatchMessage(Handler.java:99)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at android.os.Looper.loop(Looper.java:137)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at android.app.ActivityThread.main(ActivityThread.java:5099)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at java.lang.reflect.Method.invokeNative(Native Method)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at java.lang.reflect.Method.invoke(Method.java:511)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:803)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:570)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at dalvik.system.NativeStart.main(Native Method)
03-31 12:35:38.660: E/AndroidRuntime(16560): Caused by: java.lang.NullPointerException
03-31 12:35:38.660: E/AndroidRuntime(16560):    at com.example.kitchen_application.MainActivity.onCreate(MainActivity.java:30)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at android.app.Activity.performCreate(Activity.java:5117)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)
03-31 12:35:38.660: E/AndroidRuntime(16560):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2150)
03-31 12:35:38.660: E/AndroidRuntime(16560):    ... 11 more
03-31 12:35:39.982: I/Process(16560): Sending signal. PID: 16560 SIG: 9
03-31 12:36:19.714: D/AndroidRuntime(17185): Shutting down VM
03-31 12:36:19.714: W/dalvikvm(17185): threadid=1: thread exiting with uncaught exception (group=0x40d79ae0)
03-31 12:36:19.794: E/AndroidRuntime(17185): FATAL EXCEPTION: main
03-31 12:36:19.794: E/AndroidRuntime(17185): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.kitchen_application/com.example.kitchen_application.MainActivity}: java.lang.NullPointerException
03-31 12:36:19.794: E/AndroidRuntime(17185):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2186)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2236)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at android.app.ActivityThread.access$600(ActivityThread.java:145)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1238)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at android.os.Handler.dispatchMessage(Handler.java:99)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at android.os.Looper.loop(Looper.java:137)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at android.app.ActivityThread.main(ActivityThread.java:5099)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at java.lang.reflect.Method.invokeNative(Native Method)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at java.lang.reflect.Method.invoke(Method.java:511)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:803)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:570)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at dalvik.system.NativeStart.main(Native Method)
03-31 12:36:19.794: E/AndroidRuntime(17185): Caused by: java.lang.NullPointerException
03-31 12:36:19.794: E/AndroidRuntime(17185):    at com.example.kitchen_application.MainActivity.onCreate(MainActivity.java:28)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at android.app.Activity.performCreate(Activity.java:5117)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)
03-31 12:36:19.794: E/AndroidRuntime(17185):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2150)
03-31 12:36:19.794: E/AndroidRuntime(17185):    ... 11 more
03-31 12:36:21.236: I/Process(17185): Sending signal. PID: 17185 SIG: 9

Before creating `MyDatabase` instance you must Copy that DB to your `Path`. becoz here in your code you're trying to copy that `DB` from `Assets`. and it's wrong — M D, Mar 31 '15 at 07:35
which line showing error ?. its connecting to the database file ?. — Rince Thomas, Mar 31 '15 at 07:36
Change this from `button1.findViewById(R.id.button1);` to `button1 = (Button)findViewById(R.id.button1);` Show error log line too. — Piyush, Mar 31 '15 at 08:24

score 0 · Accepted Answer · answered Mar 31 '15 at 08:34

In logcat there is no any specification that the error is because of your External database. Simply error is on onCreate() method. On that method you have just declared button1, you need to initialize the button. So you need to change that from

button1.findViewById(R.id.button1);

to

button1 = (Button)findViewById(R.id.button1);

score 0 · Answer 2 · answered Mar 31 '15 at 08:39

try like this :

 private static final int DATABASE_VERSION=1;
    private SQLiteDatabase OurDb;
    private final Context myContext;
    private static String DB_PATH = "/data/data/com.example.classroom/databases/";



            /**
             * Constructor
             * Takes and keeps a reference of the passed context in order to access to the application assets and resources.
             * @param context
             */
            public DbHelper(Context context) {

                super(context, DATABASE_NAME, null, 1);
                this.myContext = context;
            }   

          /**
             * Creates a empty database on the system and rewrites it with your own database.
             * */

            /**
             * Check if the database already exist to avoid re-copying the file each time you open the application.
             * @return true if it exists, false if it doesn't
             */
            private boolean checkDataBase(){

                SQLiteDatabase checkDB = null;

                try{
                    String myPath = DB_PATH + DATABASE_NAME;
                    checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

                }catch(SQLiteException e){

                    //database does't exist yet.

                }

                if(checkDB != null){

                    checkDB.close();

                }

                return checkDB != null ? true : false;
            }

            /**
             * Copies your database from your local assets-folder to the just created empty database in the
             * system folder, from where it can be accessed and handled.
             * This is done by transfering bytestream.
             * */
            private void copyDataBase() throws IOException{

                //Open your local db as the input stream
                InputStream myInput = myContext.getAssets().open(DATABASE_NAME);

                // Path to the just created empty db
                String outFileName = DB_PATH + DATABASE_NAME;

                //Open the empty db as the output stream
                OutputStream myOutput = new FileOutputStream(outFileName);

                //transfer bytes from the inputfile to the outputfile
                byte[] buffer = new byte[1024];
                int length;
                while ((length = myInput.read(buffer))>0){
                    myOutput.write(buffer, 0, length);
                }
                 Log.v("log", "copy finish");
                //Close the streams
                myOutput.flush();
                myOutput.close();
                myInput.close();

            }



            @Override
            public synchronized void close() {

                    if(OurDb != null)
                        OurDb.close();

                    super.close();

            }

            @Override
            public void onCreate(SQLiteDatabase db) {

            }

            @Override
            public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

            }

            public void openDataBase() throws SQLException{
                // TODO Auto-generated method stub
                //Open the database
                String myPath = DB_PATH + DATABASE_NAME;
                OurDb = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

            }

            public void createDataBase()  throws IOException{
                // TODO Auto-generated method stub

                boolean dbExist = checkDataBase();

                if(dbExist){
                    //do nothing - database already exist
                    Toast.makeText(myContext, "exist", Toast.LENGTH_SHORT).show();
                }else{

                    //By calling this method and empty database will be created into the default system path
                       //of your application so we are gonna be able to overwrite that database with our database.
                    Toast.makeText(myContext, "creating", Toast.LENGTH_SHORT).show();
                    this.getReadableDatabase();
                    try {

                        copyDataBase();

                    } catch (IOException e) {

                        Log.v("log",e.toString());
                        throw new Error("Error copying database");


                    }
                }
            }

don't forget to change pakage name. – kumar kundan Mar 31 '15 at 08:42 — kumar kundan, Mar 31 '15 at 08:42

Accessing the external already created database.But the Code isnt working

2 Answers2