Issue with using external sqlite database in android app

Question

Been breaking my head over using an externally created database(a wordlist with 109,000 records and size 6.307MB). I need help with figuring out just what is going wrong here. Any answers would be greatly appreciated.

This is the code:



import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.os.Build;
import android.app.*;
import android.database.Cursor;

public class MainActivity extends Activity 
{
    private DatabaseHelper db;
    private Cursor c;
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        String[] a = new String[100];
        int i=0;

       db.openDataBase();
       c = db.getWords("sl");
       db.close();

       while(c.isAfterLast())
       {
           a[i++]=c.getString(c.getColumnIndex("WORD"));
           c.moveToNext();
       }

       ListView l = (ListView)findViewById(R.id.listView1);
       l.setAdapter(new ArrayAdapter(this,android.R.layout.simple_list_item_1,a));
    }

}

this is the helper class



import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.database.*;
import android.database.sqlite.*;
import android.content.*;

import android.app.*;

public class DatabaseHelper extends SQLiteOpenHelper
{

private static String DB_PATH = "/data/data/com.example.attempt/databases/";

// Data Base Name.
private static final String DATABASE_NAME = "dict.db";
// Data Base Version.
private static final int DATABASE_VERSION = 1;
// Table Names of Data Base.
static final String TABLE_Name1 = "WORDS";


public Context context;
static SQLiteDatabase sqliteDataBase;

public DatabaseHelper(Context context) 
{
super(context, DATABASE_NAME, null ,DATABASE_VERSION);
this.context = context;

}

@Override
public void onCreate(SQLiteDatabase arg0)
{

}
//check if the database exists
public void createDataBase() throws IOException
{
boolean databaseExist = checkDataBase();

if(databaseExist)
{
// Do Nothing.
}
else
{
this.getWritableDatabase();

copyDataBase();

// TODO Auto-generated catch block

}
}// end if else dbExist
// end createDataBase().
public boolean checkDataBase()
{
File databaseFile = new File(DB_PATH + DATABASE_NAME);
return databaseFile.exists();
}

private void copyDataBase() throws IOException
{
//Open your local db as the input stream
InputStream myInput = context.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 input file to the output file
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();
}

/**
* This method opens the data base connection.
* First it create the path up till data base of the device.
* Then create connection with data base.
*/
public void openDataBase() throws SQLException
{
//Open the database

try {
createDataBase();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String myPath = DB_PATH + DATABASE_NAME;

sqliteDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}

/**
* This Method is used to close the data base connection.
*/
@Override
public synchronized void close() 
{
if(sqliteDataBase != null)
sqliteDataBase.close();
super.close();
}
//declare methods to fetch data
public Cursor getWords(String cat)
{

return sqliteDataBase.query("WORDS",new String[]{"WORD"},"CAT="+"'"+cat+"'", null, null,null,null);

}

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

}

}

here is the logcat shown after debugging:



04-19 12:17:32.463: D/dalvikvm(4040): GC_FOR_ALLOC freed 58K, 10% free 3450K/3832K, paused 317ms, total 324ms
04-19 12:17:34.073: D/dalvikvm(4040): GC_FOR_ALLOC freed 3K, 10% free 3668K/4056K, paused 414ms, total 415ms
04-19 12:17:34.073: I/dalvikvm-heap(4040): Grow heap (frag case) to 6.307MB for 2536936-byte allocation
04-19 12:17:34.603: D/dalvikvm(4040): GC_FOR_ALLOC freed <1K, 6% free 6145K/6536K, paused 520ms, total 520ms
04-19 12:17:35.623: D/AndroidRuntime(4040): Shutting down VM
04-19 12:17:35.623: W/dalvikvm(4040): threadid=1: thread exiting with uncaught exception (group=0xb1a8bba8)
04-19 12:17:35.673: E/AndroidRuntime(4040): FATAL EXCEPTION: main
04-19 12:17:35.673: E/AndroidRuntime(4040): Process: com.example.lexicant, PID: 4040
04-19 12:17:35.673: E/AndroidRuntime(4040): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.lexicant/com.example.lexicant.MainActivity}: java.lang.NullPointerException
04-19 12:17:35.673: E/AndroidRuntime(4040):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at android.os.Handler.dispatchMessage(Handler.java:102)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at android.os.Looper.loop(Looper.java:136)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at android.app.ActivityThread.main(ActivityThread.java:5017)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at java.lang.reflect.Method.invokeNative(Native Method)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at java.lang.reflect.Method.invoke(Method.java:515)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at dalvik.system.NativeStart.main(Native Method)
04-19 12:17:35.673: E/AndroidRuntime(4040): Caused by: java.lang.NullPointerException
04-19 12:17:35.673: E/AndroidRuntime(4040):     at com.example.lexicant.MainActivity.onCreate(MainActivity.java:30)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at android.app.Activity.performCreate(Activity.java:5231)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
04-19 12:17:35.673: E/AndroidRuntime(4040):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
04-19 12:17:35.673: E/AndroidRuntime(4040):     ... 11 more
04-19 12:19:09.363: I/Process(4040): Sending signal. PID: 4040 SIG: 9
04-19 12:25:08.663: D/dalvikvm(5842): GC_FOR_ALLOC freed 66K, 11% free 3450K/3836K, paused 242ms, total 247ms
04-19 12:25:09.283: D/dalvikvm(5842): GC_FOR_ALLOC freed 3K, 10% free 3668K/4060K, paused 42ms, total 43ms
04-19 12:25:09.283: I/dalvikvm-heap(5842): Grow heap (frag case) to 6.307MB for 2536936-byte allocation
04-19 12:25:09.353: D/dalvikvm(5842): GC_FOR_ALLOC freed <1K, 7% free 6145K/6540K, paused 58ms, total 58ms
04-19 12:25:09.763: D/AndroidRuntime(5842): Shutting down VM
04-19 12:25:09.773: W/dalvikvm(5842): threadid=1: thread exiting with uncaught exception (group=0xb1a8bba8)
04-19 12:25:09.843: E/AndroidRuntime(5842): FATAL EXCEPTION: main
04-19 12:25:09.843: E/AndroidRuntime(5842): Process: com.example.lexicant, PID: 5842
04-19 12:25:09.843: E/AndroidRuntime(5842): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.lexicant/com.example.lexicant.MainActivity}: java.lang.NullPointerException
04-19 12:25:09.843: E/AndroidRuntime(5842):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at android.os.Handler.dispatchMessage(Handler.java:102)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at android.os.Looper.loop(Looper.java:136)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at android.app.ActivityThread.main(ActivityThread.java:5017)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at java.lang.reflect.Method.invokeNative(Native Method)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at java.lang.reflect.Method.invoke(Method.java:515)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at dalvik.system.NativeStart.main(Native Method)
04-19 12:25:09.843: E/AndroidRuntime(5842): Caused by: java.lang.NullPointerException
04-19 12:25:09.843: E/AndroidRuntime(5842):     at com.example.lexicant.MainActivity.onCreate(MainActivity.java:30)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at android.app.Activity.performCreate(Activity.java:5231)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
04-19 12:25:09.843: E/AndroidRuntime(5842):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
04-19 12:25:09.843: E/AndroidRuntime(5842):     ... 11 more
04-19 12:25:15.073: I/Process(5842): Sending signal. PID: 5842 SIG: 9

M D · Accepted Answer · 2014-04-19 16:36:00Z

1

I think you forget to initialized DatabaseHelper db class like below

DatabaseHelper db=new DatabaseHelper(MainActivity.this);

and without initialized db you access db.openDataBase(); method so you got NullPointerException

answered Apr 19, 2014 at 16:36

M D

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