open data base from sqlite Database in android

CopyDbActivity.java


package amitsharma.opendatabase.com;


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

import com.example.opendatabase.R;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class CopyDbActivity extends Activity {
    /** Called when the activity is first created. */
Cursor c=null;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
     
        ((Button)findViewById(R.id.button1)).setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {

     
        DatabaseHelper myDbHelper = new DatabaseHelper(CopyDbActivity.this);
        try {

        myDbHelper.createDataBase();

  } catch (IOException ioe) {

  throw new Error("Unable to create database");

  }

  try {

  myDbHelper.openDataBase();

  }catch(SQLException sqle){

  throw sqle;

  }
  Toast.makeText(CopyDbActivity.this, "Success", Toast.LENGTH_SHORT).show();

 

  c=myDbHelper.query("EMP_TABLE", null, null, null, null,null, null, null,null, null
 
  ,null,null, null
 
  );
  if(c.moveToFirst())
            {
                do {
           
                Toast.makeText(CopyDbActivity.this,
                            "_id: " + c.getString(0) + "\n" +
                            "E_NAME: " + c.getString(1) + "\n" +
                            "E_AGE: " + c.getString(2) + "\n" +
                            "E_DEPT:  " + c.getString(3),
                            Toast.LENGTH_LONG).show();
               
                } while (c.moveToNext());
            }
}
});
     
             
     
    }
}


DatabaseHelper.java


package amitsharma.opendatabase.com;

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



import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;

public class DatabaseHelper extends SQLiteOpenHelper{

    //The Android's default system path of your application database.
    String DB_PATH =null;

    private static String DB_NAME = "extenalDB";

    private SQLiteDatabase myDataBase;
 
    private final Context myContext;

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

    super(context, DB_NAME, null, 1);
        this.myContext = context;
        DB_PATH="/data/data/"+context.getPackageName()+"/"+"databases/";
    }

  /**
     * Creates a empty database on the system and rewrites it with your own database.
     * */
    public void createDataBase() throws IOException{

    boolean dbExist = checkDataBase();

    if(dbExist){
    //do nothing - database already exist
    }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.
        this.getReadableDatabase();

        try {

    copyDataBase();

    } catch (IOException e) {

        throw new Error("Error copying 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 + DB_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(DB_NAME);

    // Path to the just created empty db
    String outFileName = DB_PATH + DB_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);
    }

    //Close the streams
    myOutput.flush();
    myOutput.close();
    myInput.close();

    }

    public void openDataBase() throws SQLException{

    //Open the database
        String myPath = DB_PATH + DB_NAME;
    myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

    }

    @Override
public synchronized void close() {

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

       super.close();

}
 


@Override
public void onCreate(SQLiteDatabase db) {

}

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

}
 //return cursor
public Cursor query(String table,String[] columns, String selection,String[] selectionArgs,String groupBy,String having,String[] orderBy,String youare,String myname, Object object, Object object2, Object object3, Object object4){
return myDataBase.query("EMP_TABLE", null, null, null, null, null, null, null);


}


}




main.xml:-
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".CopyDbActivity" >

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="93dp"
        android:text="open" />

</RelativeLayout>

manifestfile:-

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.example.opendatabase"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk

        android:minSdkVersion="8"

        android:targetSdkVersion="17" />

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

        <activity

            android:name="amitsharma.opendatabase.com.CopyDbActivity"

            android:label="@string/app_name" >

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

        

        

        <activity android:name="amitsharma.opendatabase.com.DatabaseHelper"

                  android:label="@string/app_name">

        </activity>

        

    </application>

</manifest>