Android SQLite how can retrieve data

Prerequisite

If you not understand this lecture .how can Retrieve Data into android SQLite Database.You should also read my previous lectures Android how can add data into SQLite  and Contextual Action mode in android studio . After reading these lecture you will also able to create Database of your Application And  also retrieve data from database.

What is SQLite

SQLite is a embedded (RDBMS) Stand for Relation DataBase Management system.Most relation database such as ORACAL and SQL are example that are working independently and store the information.SQLite is referred to as embedded because it is provided in the form of a library that is linked into applications.The code for SQLite is in the public domain and is thus free for use for any purpose, commercial or private.There is no sever that are running in the background.All the Database function are perform internally.

Introduction

In this lecture well we describe how can create Database in android studio.And also describe what is SQLite.why we can use it.After Reading this lecture you will understand how can create Retrieve data from Database in android And i hope you will create Database of your application and also retrieve data from database after reading this serios.

Description of Retrieve data into Database

In this lecture we will describe how can retrieve data in android SQLite database.This is a second lecture of android SQLite series.In my previous lecture i have to show how can add data into database.If you not understand this lecture you will also see my previous post.All the information were saved in database.So we retrieve data such as contact name mobile number and email address from database. and we will show in a list view.First of all we create project in android studio.Every project contain two file first is java class file and second is layout XML file.And we open a layout.XML file and add a button when user click on a button open a new activity.In that activity you will see all the data that are retrieve from database.So this is a work that will done this section.please read this lecture carefully all the detail is provides step by step.For more about Retrieve data into android SQLite database please click on Retrieve data into android SQLite database.

Layout XML

Now we create a new Layout.

Step 1=<- create a new Layout name data_list_layout->Right click> the ->layout folder-> select ->New option-> and click ->layout resource folder->

Step3=Step2->WriteName->Ok.

Different property that are used in layout.xml file  explain here

• warp_content   warp_content means height and width similar to the text that are entered.
• Match_parent   means height and width similar to parent.
• Edit text              The Edit Text control allows a user to enter text into an application
• Button                  When user click on a button store information into database and show message

And Write the following code data_List_layout. XML file

<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"
    tools:context="customspinner.alienslab.com.adddata.DataListActivity"
    android:background="#A47DED"
    >

<ListView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/list_view"
    >
</ListView>

</RelativeLayout>

•  Step 5=<- create a new name row_layout->Right click> the ->layout folder-> select ->New option-> and click>layout resource folder->
•  Step6=Step5->WriteName->Ok
• if you not understand this please read first step1
• In this example we are going to create a simple UI that includes only (Text  view)  with Different attributes.And Write the following code into row_layout.XML file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" android:layout_width="match_parent"
    android:layout_height="40dp"
    android:background="#A47DED"
    >

    <TextView
        android:layout_marginTop="10dp"
        android:layout_width="100dp"
        android:layout_height="wrap_content"
        android:id="@+id/test_user_name"
        android:text="UserName"
        android:gravity="center"
        android:textColor="#000000"
        />

    <TextView
        android:layout_marginTop="10dp"
        android:layout_width="130dp"
        android:layout_height="wrap_content"
        android:id="@+id/test_user_mob"
        android:text="UserMobile"
        android:gravity="center"
        android:textColor="#000000"/>
        />
    <TextView
        android:layout_marginTop="10dp"
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:id="@+id/test_user_Email"
        android:text="UserEmail"
        android:gravity="center"
        android:textColor="#000000"
        />
        />
</LinearLayout>

Write the following code activity_main_layout. XML file

<LinearLayout 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:orientation="vertical"
tools:context=".LinearLayout"
android:background="#000000"
    >

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="sendMessage"
    android:text="@string/button1"
    android:layout_gravity="center"
    />

    <Button
        android:id="@+id/view_data"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="showData"
        android:text="@string/view_data"
        android:layout_gravity="center"
        />

</LinearLayout>

Now you may open the Graphical layout editor to preview the User Interface you created.

Step7=Create new class <-NewContactActivity ->Right click-> the ->package name ->select ->New option-> and click-> java class that will show in below. 

<-WriteName->Ok

And Write the following code NewContactActivity. java class

public class NewContactActivity extends Activity {
    EditText ContactName,MobileNumber,EmailAddress;
    Context context=this;
    UserDbHelper userDbHelper;
    SQLiteDatabase sqLiteDatabase;


    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.adddata_layout);
        ContactName=(EditText)findViewById(R.id.contant_name);
        MobileNumber=(EditText)findViewById(R.id.mobile_number);
        EmailAddress=(EditText)findViewById(R.id.email_address);
    }

    public void addContant(View view)
    {
        String name=ContactName.getText().toString();
        String mob= MobileNumber.getText().toString();
        String email=EmailAddress.getText().toString();
        userDbHelper=new UserDbHelper(context);
        sqLiteDatabase=userDbHelper.getWritableDatabase();
        userDbHelper.addinnformation(name,mob,email,sqLiteDatabase);
        Toast.makeText(getBaseContext(),"Data saved",Toast.LENGTH_LONG).show();
        userDbHelper.close();
    }
}

• Step8=Create new class <-UserContract ->Right click-> the ->package name ->select ->New option-> and click-> java class that will show in above. 
•  Step9=Step8->WriteName->Ok
• if you not understand this please read first step7
• And Write the following code UserContract. java class

public class UserContract {

    public static abstract class NewUserInfo
    {
     public static final String USER_NAME="user_name";
        public static final String USER_MOB="user_mob";
        public static final String USER_EMAIL="user_email";
        public static final String TABLE_NAME="user_info";
    }
}

• Step10=Create new class <-UserDbHandler ->Right click-> the ->package name ->select ->New option-> and click-> java class that will show in above. 
•  Step11=Step10->WriteName->Ok.
• if you not understand this  please read step 7.

And Write the following code UserDbHandler. java class

package customspinner.alienslab.com.adddata;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;


public class UserDbHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME="USERINFO.DB";
    private static final int DATABASE_VERSION=5;
    private static final String CREATE_QUERY="CREATE TABLE "+ UserContract.NewUserInfo.TABLE_NAME+"(id INTEGER, "+
            UserContract.NewUserInfo.USER_NAME+" TEXT, "+ UserContract.NewUserInfo.USER_MOB+" TEXT, "
            + UserContract.NewUserInfo.USER_EMAIL+" TEXT );";

    public UserDbHelper(Context context){

      super(context,DATABASE_NAME,null,DATABASE_VERSION);
        Log.e("DATABASE OPERATION", "Database created / opened.....");

    }
    @Override
    public void onCreate(SQLiteDatabase db) {

        db.execSQL(CREATE_QUERY);
        Log.e("DATABASE OPERATION", "Table create..."+CREATE_QUERY);
    }
    public void addinnformation(String name,String mob,String email,SQLiteDatabase db){

     ContentValues contentValue = new ContentValues();
        contentValue.put(UserContract.NewUserInfo.USER_NAME,name);
        contentValue.put(UserContract.NewUserInfo.USER_MOB,mob);
        contentValue.put(UserContract.NewUserInfo.USER_EMAIL,email);
        db.insert(UserContract.NewUserInfo.TABLE_NAME, null, contentValue);
        Log.e("DATABASE OPERATION", "One row is insert");

    }

     public Cursor getinformation(SQLiteDatabase db){
         Cursor cursor;
         String[] projections={ UserContract.NewUserInfo.USER_NAME,UserContract.NewUserInfo.USER_MOB,UserContract.NewUserInfo.USER_EMAIL};
        cursor= db.query(UserContract.NewUserInfo.TABLE_NAME, projections, null, null, null, null, null);
         return cursor;
   }

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

    }
}

• Step12=Create new class <-ListDataAdpter ->Right click-> the ->package name ->select ->New option-> and click-> java class that will show in above. 
•  Step13=Step12->WriteName->Ok.
• if you not understand this  please read step 7.
• And Write the following code ListDataAdpter. java class

package customspinner.alienslab.com.adddata;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

public class ListDataAdpter extends ArrayAdapter {
    List list= new ArrayList();
    public ListDataAdpter(Context context,int resource){
        super(context,resource);
    }
     static class LayoutHandler{
         TextView NAME,MOB,EMAIL;
     }
    public void add(Object object){
        super.add(object);
        list.add(object);

    }
    public int getCount(){
        return list.size();
    }
    public Object getTtem(int position){
        return list.get(position);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row = convertView;
        LayoutHandler layoutHandler;
        if(row == null)
        {
            LayoutInflater layoutInflater =(LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            row=layoutInflater.inflate(R.layout.row_layout,parent,false);
            layoutHandler=new LayoutHandler();
            layoutHandler.NAME=(TextView)row.findViewById(R.id.test_user_name);
            layoutHandler.MOB=(TextView)row.findViewById(R.id.test_user_mob);
            layoutHandler.EMAIL=(TextView)row.findViewById(R.id.test_user_Email);
            row.setTag(layoutHandler);
        }

        else{
            layoutHandler=(LayoutHandler)row.getTag();
        }
         DataProvider dataProvider=(DataProvider)this.getTtem(position);
        layoutHandler.NAME.setText(dataProvider.getName());
        layoutHandler.MOB.setText(dataProvider.getMob());
        layoutHandler.EMAIL.setText(dataProvider.getEmail());
        return row;
    }
}

• Step14=Create new class <-DataProvider ->Right click-> the ->package name ->select ->New option-> and click-> java class that will show in above. 
•  Step15=Step14->WriteName->Ok.
• if you not understand this  please read step 7.
• And Write the following code DataProvider. java class

public class DataProvider {
    private String name;
    private String mob;
    private String email;

public DataProvider(String name,String mob,String email)
{
    this.name =name;
    this.mob=mob;
    this.email=email;

}

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getMob() {
        return mob;
    }

    public void setMob(String mob) {
        this.mob = mob;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}

• Step16=Create new class <-DataListActivity ->Right click-> the ->package name ->select ->New option-> and click-> java class that will show in above. 
•  Step17=Step16->WriteName->Ok.
• if you not understand this  please read step 7.
• And Write the following code DataListActivity. java class

package customspinner.alienslab.com.adddata;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ListView;


public class DataListActivity extends ActionBarActivity {
    ListView listView;
    SQLiteDatabase sqLiteDatabase;
    UserDbHelper userDbHelper;
    Cursor cursor;
    ListDataAdpter listDataAdpter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.data_list_layout);
        listView=(ListView)findViewById(R.id.list_view);
        listDataAdpter=new ListDataAdpter(getApplicationContext(),R.layout.row_layout);
        listView.setAdapter(listDataAdpter);
        userDbHelper=new UserDbHelper(getApplicationContext());
        sqLiteDatabase=userDbHelper.getReadableDatabase();
        cursor=userDbHelper.getinformation(sqLiteDatabase);
        if(cursor.moveToFirst())
        {
            do {
                String name,mob,email;
                name= cursor.getString(0);
                mob= cursor.getString(1);
                email=cursor.getString(2);
                DataProvider dataProvider=new DataProvider(name,mob,email);
                listDataAdpter.add(dataProvider);

            }while (cursor.moveToNext());
        }
    }


}

And Write the following code MainActivity. java class

package customspinner.alienslab.com.adddata;

import android.app.Activity;
import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;


public class MainActivity extends Activity {

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


    public void sendMessage(View view)
    {
        Intent intent = new Intent(MainActivity.this,NewContactActivity.class);
        startActivity(intent);
    }

    public void showData(View view)
    {
        Intent i = new Intent(MainActivity.this,DataListActivity.class);
        startActivity(i);
    }

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

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

Run the Application

Run the application and if you click on a first button the a new activity will open in this activity consists of three Edit text  and a button .when user add information  and click on save button then all the information will saved in database.and if user click on second button then a new activity open and show all the information that are save in database.

Conclusion

In this lecture we learn about Android SqLite database how can view data from database.. I hope you will understand this lecture.Thank you for reading this lecture Hope you got the idea.

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