In android, we have different storage options such as shared preferences, internal storage, external storage, SQLite storage, etc. to store and retrieve the application data based on our requirements.
In previous chapters, we learned how to use shared preferences, internal storage, external storage and now we will see how to use the SQLite Database option to store structured data in a private database.
SQLite is an open-source lightweight relational database management system (RDBMS) to perform database operations, such as storing, updating, retrieving data from the database. To know more about SQLite, check this SQLite Tutorial with Examples.
Generally, in our android applications Shared Preferences, Internal Storage and External Storage options are useful to store and maintain a small amount of data. In case, if we want to deal with large amounts of data, then SQLite database is the preferable option to store and maintain the data in a structured format.
By default, Android comes with built-in SQLite Database support so we don’t need to do any configurations.
Just like we save the files on the device’s internal storage, Android stores our database in a private disk space that’s associated with our application and the data is secure, because by default this area is not accessible to other applications.
The package android.database.sqlite contains all the required APIs to use an SQLite database in our android applications.
Now we will see how to create a database and required tables in SQLite and perform CRUD (insert, update, delete and select) operations in android applications.
Create Database and Tables using SQLite Helper
In android, by using SQLiteOpenHelper class we can easily create the required database and tables for our application. To use SQLiteOpenHelper, we need to create a subclass that overrides the onCreate() and onUpgrade() call-back methods.
Following is the code snippet of creating the database and tables using the SQLiteOpenHelper class in our android application.
public class DbHandler extends SQLiteOpenHelper {
private static final int DB_VERSION = 1;
private static final String DB_NAME = "usersdb";
private static final String TABLE_Users = "userdetails";
private static final String KEY_ID = "id";
private static final String KEY_NAME = "name";
private static final String KEY_LOC = "location";
private static final String KEY_DESG = "designation";
public DbHandler(Context context){
super(context,DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db){
String CREATE_TABLE = "CREATE TABLE " + TABLE_Users + "("
+ KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_NAME + " TEXT,"
+ KEY_LOC + " TEXT,"
+ KEY_DESG + " TEXT"+ ")";
db.execSQL(CREATE_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){
// Drop older table if exist
db.execSQL("DROP TABLE IF EXISTS " + TABLE_Users);
// Create tables again
onCreate(db);
}
}
If you observe above code snippet, we are creating database “usersdb” and table “userdetails” using SQLiteOpenHelper class by overriding onCreate and onUpgrade methods.
| Method | Description |
|---|---|
| onCreate() | This method is called only once throughout the application after the database is created and the table creation statements can be written in this method. |
| onUpgrade() | This method is called whenever there is an updation in the database like modifying the table structure, adding constraints to the database, etc. |
Now we will see how to perform CRUD (create, read, delete and update) operations in android applications.
Insert Data into SQLite Database
In android, we can insert data into the SQLite database by passing ContentValues to insert() method.
Following is the code snippet to insert data into the SQLite database using the insert() method in the android application.
SQLiteDatabase db = this.getWritableDatabase();
//Create a new map of values, where column names are the keys
ContentValues cValues = new ContentValues();
cValues.put(KEY_NAME, name);
cValues.put(KEY_LOC, location);
cValues.put(KEY_DESG, designation);
// Insert the new row, returning the primary key value of the new row
long newRowId = db.insert(TABLE_Users,null, cValues);
If you observe above code, we are getting the data repository in write mode and adding required values to columns and inserting into database.
Read the Data from SQLite Database
In android, we can read the data from the SQLite database using the query() method in android applications.
Following is the code snippet to read the data from the SQLite Database using a query() method in the android application.
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.query(TABLE_Users, new String[]{KEY_NAME, KEY_LOC, KEY_DESG}, KEY_ID+ "=?",new String[]{String.valueOf(userid)},null, null, null, null);
If you observe above code, we are getting the details from required table using query() method based on our requirements.
Update Data in SQLite Database
In android, we can update the data in the SQLite database using an update() method in android applications.
Following is the code snippet to update the data in the SQLite database using an update() method in the android application.
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cVals = new ContentValues();
cVals.put(KEY_LOC, location);
cVals.put(KEY_DESG, designation);
int count = db.update(TABLE_Users, cVals, KEY_ID+" = ?",new String[]{String.valueOf(id)});
If you observe above code, we are updating the details using update() method based on our requirements.
Delete Data from SQLite Database
In android, we can delete data from the SQLite database using the delete() method in android applications.
Following is the code snippet to delete the data from the SQLite database using the delete() method in the android application.
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_Users, KEY_ID+" = ?",new String[]{String.valueOf(userid)});
If you observe above code, we are deleting the details using delete() method based on our requirements.
Now we will see how to create sqlite database and perform CRUD (insert, update, delete, select) operations on SQLite Database in android application with examples.
Android SQLite Database Example
Following is the example of creating the SQLite database, insert and show the details from the SQLite database into an android listview using the SQLiteOpenHelper class.
Create a new android application using android studio and give names as SQLiteExample. In case if you are not aware of creating an app in android studio check this article Android Hello World App.
Once we create an application, create a class file DbHandler.java in \java\com.tutlane.sqliteexample path to implement SQLite database related activities for that right-click on your application folder à Go to New à select Java Class and give name as DbHandler.java.
Once we create a new class file DbHandler.java, open it and write the code like as shown below
DbHandler.java
package com.tutlane.sqliteexample;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import java.util.ArrayList;
import java.util.HashMap;
/**
* Created by tutlane on 06-01-2018.
*/
public class DbHandler extends SQLiteOpenHelper {
private static final int DB_VERSION = 1;
private static final String DB_NAME = "usersdb";
private static final String TABLE_Users = "userdetails";
private static final String KEY_ID = "id";
private static final String KEY_NAME = "name";
private static final String KEY_LOC = "location";
private static final String KEY_DESG = "designation";
public DbHandler(Context context){
super(context,DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db){
String CREATE_TABLE = "CREATE TABLE " + TABLE_Users + "("
+ KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_NAME + " TEXT,"
+ KEY_LOC + " TEXT,"
+ KEY_DESG + " TEXT"+ ")";
db.execSQL(CREATE_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){
// Drop older table if exist
db.execSQL("DROP TABLE IF EXISTS " + TABLE_Users);
// Create tables again
onCreate(db);
}
// **** CRUD (Create, Read, Update, Delete) Operations ***** //
// Adding new User Details
void insertUserDetails(String name, String location, String designation){
//Get the Data Repository in write mode
SQLiteDatabase db = this.getWritableDatabase();
//Create a new map of values, where column names are the keys
ContentValues cValues = new ContentValues();
cValues.put(KEY_NAME, name);
cValues.put(KEY_LOC, location);
cValues.put(KEY_DESG, designation);
// Insert the new row, returning the primary key value of the new row
long newRowId = db.insert(TABLE_Users,null, cValues);
db.close();
}
// Get User Details
public ArrayList<HashMap<String, String>> GetUsers(){
SQLiteDatabase db = this.getWritableDatabase();
ArrayList<HashMap<String, String>> userList = new ArrayList<>();
String query = "SELECT name, location, designation FROM "+ TABLE_Users;
Cursor cursor = db.rawQuery(query,null);
while (cursor.moveToNext()){
HashMap<String,String> user = new HashMap<>();
user.put("name",cursor.getString(cursor.getColumnIndex(KEY_NAME)));
user.put("designation",cursor.getString(cursor.getColumnIndex(KEY_DESG)));
user.put("location",cursor.getString(cursor.getColumnIndex(KEY_LOC)));
userList.add(user);
}
return userList;
}
// Get User Details based on userid
public ArrayList<HashMap<String, String>> GetUserByUserId(int userid){
SQLiteDatabase db = this.getWritableDatabase();
ArrayList<HashMap<String, String>> userList = new ArrayList<>();
String query = "SELECT name, location, designation FROM "+ TABLE_Users;
Cursor cursor = db.query(TABLE_Users, new String[]{KEY_NAME, KEY_LOC, KEY_DESG}, KEY_ID+ "=?",new String[]{String.valueOf(userid)},null, null, null, null);
if (cursor.moveToNext()){
HashMap<String,String> user = new HashMap<>();
user.put("name",cursor.getString(cursor.getColumnIndex(KEY_NAME)));
user.put("designation",cursor.getString(cursor.getColumnIndex(KEY_DESG)));
user.put("location",cursor.getString(cursor.getColumnIndex(KEY_LOC)));
userList.add(user);
}
return userList;
}
// Delete User Details
public void DeleteUser(int userid){
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_Users, KEY_ID+" = ?",new String[]{String.valueOf(userid)});
db.close();
}
// Update User Details
public int UpdateUserDetails(String location, String designation, int id){
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cVals = new ContentValues();
cVals.put(KEY_LOC, location);
cVals.put(KEY_DESG, designation);
int count = db.update(TABLE_Users, cVals, KEY_ID+" = ?",new String[]{String.valueOf(id)});
return count;
}
}
If you observe above code, we implemented all SQLite Database related activities to perform CRUD operations in android application.
Now open activity_main.xml file from \res\layout folder path and write the code like as shown below.
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/fstTxt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="100dp"
android:layout_marginTop="150dp"
android:text="Name" />
<EditText
android:id="@+id/txtName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="100dp"
android:ems="10"/>
<TextView
android:id="@+id/secTxt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Location"
android:layout_marginLeft="100dp" />
<EditText
android:id="@+id/txtLocation"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="100dp"
android:ems="10" />
<TextView
android:id="@+id/thirdTxt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Designation"
android:layout_marginLeft="100dp" />
<EditText
android:id="@+id/txtDesignation"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="100dp"
android:ems="10" />
<Button
android:id="@+id/btnSave"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="100dp"
android:text="Save" />
</LinearLayout>
Now we will create another layout resource file details.xml in \res\layout path to show the details in custom listview from SQLite Database for that right click on your layout folder à Go to New à select Layout Resource File and give name as details.xml.
Once we create a new layout resource file details.xml, open it and write the code like as shown below
details.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<ListView
android:id="@+id/user_list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:dividerHeight="1dp" />
<Button
android:id="@+id/btnBack"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="20dp"
android:text="Back" />
</LinearLayout>
Create an another layout file (list_row.xml) in /res/layout folder to show the data in listview, for that right click on layout folder à add new Layout resource file à Give name as list_row.xml and write the code like as shown below.
list_row.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:padding="5dip" >
<TextView
android:id="@+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textStyle="bold"
android:textSize="17dp" />
<TextView
android:id="@+id/designation"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/name"
android:layout_marginTop="7dp"
android:textColor="#343434"
android:textSize="14dp" />
<TextView
android:id="@+id/location"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/designation"
android:layout_alignBottom="@+id/designation"
android:layout_alignParentRight="true"
android:textColor="#343434"
android:textSize="14dp" />
</RelativeLayout>
Now open your main activity file MainActivity.java from \java\com.tutlane.sqliteexample path and write the code like as shown below
MainActivity.java
package com.tutlane.sqliteexample;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
EditText name, loc, desig;
Button saveBtn;
Intent intent;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
name = (EditText)findViewById(R.id.txtName);
loc = (EditText)findViewById(R.id.txtLocation);
desig = (EditText)findViewById(R.id.txtDesignation);
saveBtn = (Button)findViewById(R.id.btnSave);
saveBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String username = name.getText().toString()+"\n";
String location = loc.getText().toString();
String designation = desig.getText().toString();
DbHandler dbHandler = new DbHandler(MainActivity.this);
dbHandler.insertUserDetails(username,location,designation);
intent = new Intent(MainActivity.this,DetailsActivity.class);
startActivity(intent);
Toast.makeText(getApplicationContext(), "Details Inserted Successfully",Toast.LENGTH_SHORT).show();
}
});
}
}
If you observe above code, we are taking entered user details and inserting into SQLite database and redirecting the user to another activity.
Now we will create another activity file DetailsActivity.java in \java\com.tutlane.sqliteexample path to show the details from the SQLite database for that right-click on your application folder à Go to New à select Java Class and give name as DetailsActivity.java.
Once we create a new activity file DetailsActivity.java, open it and write the code like as shown below
DetailsActivity.java
package com.tutlane.sqliteexample;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import java.util.ArrayList;
import java.util.HashMap;
/**
* Created by tutlane on 05-01-2018.
*/
public class DetailsActivity extends AppCompatActivity {
Intent intent;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.details);
DbHandler db = new DbHandler(this);
ArrayList<HashMap<String, String>> userList = db.GetUsers();
ListView lv = (ListView) findViewById(R.id.user_list);
ListAdapter adapter = new SimpleAdapter(DetailsActivity.this, userList, R.layout.list_row,new String[]{"name","designation","location"}, new int[]{R.id.name, R.id.designation, R.id.location});
lv.setAdapter(adapter);
Button back = (Button)findViewById(R.id.btnBack);
back.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
intent = new Intent(DetailsActivity.this,MainActivity.class);
startActivity(intent);
}
});
}
}
If you observe above code, we are getting the details from SQLite database and binding the details to android listview. Now we need to add this newly created activity in AndroidManifest.xml file in like as shown below.
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.tutlane.sqliteexample">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".DetailsActivity" android:label="SQLite Example - Details"></activity>
</application>
</manifest>
If you observe above example, we are saving entered details in SQLite database and redirecting the user to another activity file (DetailsActivity.java) to show the users details and added all the activities in AndroidManifest.xml file.
Output of Android SQLite Database Example
When we run the above example in the android emulator we will get a result as shown below.
If you observe the above result, the entered user details are storing in the SQLite database and redirecting the user to another activity file to show the user details from the SQLite database. After that, if we click on the Back button, it will redirect the user to the login page.
This is how we can use the SQLite database to perform CRUD (insert, update, delete and select) operations in android applications to store and retrieve data from the SQLite database based on our requirements.
