How to create database openhelper in android

creating data base openhelper in android is most importent part in android appolication devlopment and when you write the code for an application then you need to create a data base open helper for your application this should be helpful for your app.



write the following code into the main class on your application:

package com.open.handler;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class SqliteOPenhelperDemoActivity extends Activity implements
OnClickListener {
Button login;
EditText user, pass;
String username, passlock;
DBHandler mydb;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
login = (Button) findViewById(R.id.button1);
pass = (EditText) findViewById(R.id.editText2);
user = (EditText) findViewById(R.id.editText1);
login.setOnClickListener(this);
System.out.println("before gng to database");
mydb = new DBHandler(this);
System.out.println("am bck frm database");

}

public void onClick(View v) {
// TODO Auto-generated method stub

username = user.getText().toString();
passlock = pass.getText().toString();

System.out.println("insert values before gng to database");

mydb.insertting_values(username, passlock);

System.out.println("am back fnm database");

startActivity(new Intent(this,Retrievedata.class));

}
}



create batabase Handler for create database:

package com.open.handler;

import java.util.ArrayList;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class DBHandler extends SQLiteOpenHelper {
static String name_db = "HelperDataBase";
static int version = 1;
SQLiteDatabase db;

public DBHandler(Context context) {
super(context, name_db, null, version);
// TODO Auto-generated constructor stub
// creating the db
System.out.println("in constructor");

db = getWritableDatabase();

}

@Override
public void onCreate(SQLiteDatabase db) {
System.out.println("in oncreate mtd");

// TODO Auto-generated method stub
// creating table
db.execSQL("create table if not exists Users(Username Text,Password Text)");

}

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

}

public void insertting_values(String username, String passlock) {
// TODO Auto-generated method stub

System.out.println("in insert method");

db.execSQL("insert into Users values('" + username + "','" + passlock
+ "')");

}

public ArrayList<String> retrievefunction() {
// TODO Auto-generated method stub

ArrayList<String> alist = new ArrayList<String>();
System.out.println("in retrieve function");
Cursor c = db.rawQuery("select * from Users", null);
c.moveToFirst();
do {



String name = c.getString(c.getColumnIndex("Username"));
String pass = c.getString(c.getColumnIndex("Password"));
alist.add(name);
alist.add(pass);
System.out.println(" adding ");

} while (c.moveToNext());

return alist;
}

}


retreviewing the data from the database:

package com.open.handler;

import java.util.ArrayList;

import android.app.ListActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class Retrievedata extends ListActivity{


DBHandler mydb;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);

mydb=new DBHandler(this);

ArrayList<String> ad=mydb.retrievefunction();
System.out.println("cmg frm data values.....");
ListView lv=getListView();
lv.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, ad));


}

}