Over the course of this article, we will focus on Android SQLite database Tutorial. It also demonstrates how to create new table, insert records, and modify records with example.
1. What is SQLite
SQLite is an Open-Source embedded SQL database engine. This provides relational database management structure for storing user defined records in the form of tables. SQLite is light weight when it comes to resource usage and it doesn’t need to have any server setup like other RDBMS systems. It is an cross platform and self-contained database.
Android is shipped with SQLite version 3.4.0.
2. Sample TODO Application
In this tutorials we will make a simple TODO application that will store, manipulate the user created records. For the sake of simplicity we have only less number of columns in this application. You may like to extend this to make it an full-fledged application. In this example we will create a database JAVATECHIG_TODOS.DB and a table named TODO for storing all todo’s that user is creating. You can find a demo link to it on Google play.
3. Create New Database
Database names must be unique within an application, not across all applications. Let us have a look at the database structure from the below image. We have three columns in TODO table. _id is with INTEGER data type and a primary key with auto increment, subject is TEXT type and description is also TEXT type.
4. Create a New Android project
Create a new android project named “TODOApp”. Here in this example we use minSdkVersion as 14, targetSdkVersion as 19 and package name is com.javatechig.todo
5. Database Helper Class
Now let us have a look into database helper classes. Database helper DBhelper.java and SQLController.java class helps to perform all database CURD operations.
DBhelper.java
package com.javatechig.todo;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DBhelper extends SQLiteOpenHelper {
// Table Name
public static final String TABLE_NAME = "TODOS";
// Table columns
public static final String _ID = "_id";
public static final String TODO_SUBJECT = "subject";
public static final String TODO_DESC = "description";
// Database Information
static final String DB_NAME = "JAVATECHIG_TODOS.DB";
// database version
static final int DB_VERSION = 1;
// Creating table query
private static final String CREATE_TABLE = "create table " + TABLE_NAME + "(" + _ID
+ " INTEGER PRIMARY KEY AUTOINCREMENT, " + TODO_SUBJECT + " TEXT NOT NULL, " + TODO_DESC + " TEXT);";
public DBhelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
onCreate(db);
}
}
In the above code we have declared various constants which are used as database name, table name and column names. DBhelper class extends SQLiteOpenHelper class and overrides onCreate() and onUpgrade() method.
5.1. Create Database
The onCreate() method will be called on first time use of the application. Here we will construct SQLite database. This method is called only if the database file is not created before. Once the database is successfully created, it creates .DB files in your data/data/<your app package name>/databases/ folder. You can view this from DDMS from your emulator, but if you use your physical device you may not be able to browse this file unless your device is routed.
5.2. Upgrade Database
The onUpgrade() method is called only when the database version is changed. Database version is an integer value which is specified inside the DBhelper constructor.
6. Create Database Controller
It is always a best practice to define an controller or separate class for all your database operations. Here in this example we are creating an new class that performs all database related operations like add, update, delete records into table.
Before performing any database operations like add, update, delete records in a table, first open the database by calling getWritableDatabase() method. Make sure to close database connection once it is opened.
6.1. Add New TODO Record
public void insert(String name, String desc) {
ContentValues contentValue = new ContentValues();
contentValue.put(DBhelper.TODO_SUBJECT, name);
contentValue.put(DBhelper.TODO_DESC, desc);
database.insert(DBhelper.TABLE_NAME, null, contentValue);
}
6.2. Fetching All Records
public Cursor fetch() {
String[] columns = new String[] { DBhelper._ID, DBhelper.TODO_SUBJECT, DBhelper.TODO_DESC};
Cursor cursor = database.query(DBhelper.TABLE_NAME, columns, null, null, null, null, null);
if (cursor != null) {
cursor.moveToFirst();
}
return cursor;
}
6.3. Modify Record
public int update(long _id, String name, String desc) {
ContentValues contentValues = new ContentValues();
contentValues.put(DBhelper.TODO_SUBJECT, name);
contentValues.put(DBhelper.TODO_DESC, desc);
int i = database.update(DBhelper.TABLE_NAME, contentValues, DBhelper._ID + " = " + _id, null);
return i;
}
6.4. Delete Record
Refer SQLiteController class.
6.5. Close Database Connection
Refer SQLiteController class.
7. Controller Complete Code
SQLController.java
package com.javatechig.todo;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
public class SQLController {
private DBhelper dbHelper;
private Context ourcontext;
private SQLiteDatabase database;
public SQLController(Context c) {
ourcontext = c;
}
public SQLController open() throws SQLException {
dbHelper = new DBhelper(ourcontext);
database = dbHelper.getWritableDatabase();
return this;
}
public void close() {
dbHelper.close();
}
public void insert(String name, String desc) {
ContentValues contentValue = new ContentValues();
contentValue.put(DBhelper.TODO_SUBJECT, name);
contentValue.put(DBhelper.TODO_DESC, desc);
database.insert(DBhelper.TABLE_NAME, null, contentValue);
}
public Cursor fetch() {
String[] columns = new String[] { DBhelper._ID, DBhelper.TODO_SUBJECT,
DBhelper.TODO_DESC };
Cursor cursor = database.query(DBhelper.TABLE_NAME, columns, null,
null, null, null, null);
if (cursor != null) {
cursor.moveToFirst();
}
return cursor;
}
public int update(long _id, String name, String desc) {
ContentValues contentValues = new ContentValues();
contentValues.put(DBhelper.TODO_SUBJECT, name);
contentValues.put(DBhelper.TODO_DESC, desc);
int i = database.update(DBhelper.TABLE_NAME, contentValues,
DBhelper._ID + " = " + _id, null);
return i;
}
public void delete(long _id) {
database.delete(DBhelper.TABLE_NAME, DBhelper._ID + "=" + _id, null);
}
}
8. Application Activity Layout
In this example, we have three major layout files. One for listing all TODO items, second one is for adding all records and the third one is for update/deleting records.
fragment_todo_list.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="fill_parent" >
<ListView
android:id="@+id/list_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:dividerHeight="1dp"
android:padding="10dp" >
</ListView>
<TextView
android:id="@+id/empty"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="@string/empty_list_text" />
</RelativeLayout>
activity_add_record.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="20dp" >
<EditText
android:id="@+id/subject_edittext"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:hint="@string/enter_title" >
<requestFocus />
</EditText>
<EditText
android:id="@+id/description_edittext"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:hint="@string/enter_desc"
android:inputType="textMultiLine"
android:minLines="5" >
</EditText>
<Button
android:id="@+id/add_record"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="@string/add_record" />
</LinearLayout>
activity_modify_record.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="10dp" >
<EditText
android:id="@+id/subject_edittext"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="10dp"
android:ems="10"
android:hint="@string/enter_title" />
<EditText
android:id="@+id/description_edittext"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:hint="@string/enter_desc"
android:inputType="textMultiLine"
android:minLines="5" >
</EditText>
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:weightSum="2"
android:gravity="center_horizontal"
android:orientation="horizontal" >
<Button
android:id="@+id/btn_update"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/btn_update" />
<Button
android:id="@+id/btn_delete"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/btn_delete" />
</LinearLayout>
</LinearLayout>
9. Application Activity Classes
Now let us see how are the activity classes look like. We have three activity classes that does three different works. One for listing all TODO items, second adds TODO item and other helps in update/delete records.
- ContentValues is a name value pair, used to insert or update values into database tables. ContentValus object will be passed to SQLiteDatabase object
insert()andupdate()method. - Cursor is a temporary buffer area which holds results from SQLiteDatabase query.
TodoListActivity.java
package com.javatechig.todo;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.support.v4.widget.SimpleCursorAdapter;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.TextView;
public class TodoListActivity extends ActionBarActivity {
private SQLController dbcon;
private ListView listView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_emp_list);
dbcon = new SQLController(this);
dbcon.open();
listView = (ListView) findViewById(R.id.list_view);
listView.setEmptyView(findViewById(R.id.empty));
// Attach The Data From DataBase Into ListView Using Crusor Adapter
Cursor cursor = dbcon.fetch();
String[] from = new String[] { DBhelper._ID, DBhelper.TODO_SUBJECT,
DBhelper.TODO_DESC };
int[] to = new int[] { R.id.id, R.id.title, R.id.desc };
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
R.layout.activity_view_record, cursor, from, to);
adapter.notifyDataSetChanged();
listView.setAdapter(adapter);
// OnCLickListiner For List Items
listView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long viewId) {
TextView id_tv = (TextView) view.findViewById(R.id.id);
TextView title_tv = (TextView) view.findViewById(R.id.title);
TextView desc_tv = (TextView) view.findViewById(R.id.desc);
String id = id_tv.getText().toString();
String title = title_tv.getText().toString();
String desc = desc_tv.getText().toString();
Intent modify_intent = new Intent(getApplicationContext(),
ModifyTodoActivity.class);
modify_intent.putExtra("title", title);
modify_intent.putExtra("desc", desc);
modify_intent.putExtra("id", id);
startActivity(modify_intent);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.add_record) {
Intent add_mem = new Intent(this, AddTodoActivity.class);
startActivity(add_mem);
return true;
}
return super.onOptionsItemSelected(item);
}
}
AddTodoActivity.java
package com.javatechig.todo;
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 AddTodoActivity extends Activity implements OnClickListener {
private Button addTodoBtn;
private SQLController dbController;
private EditText subjectEditText;
private EditText descEditText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setTitle("Add Record");
setContentView(R.layout.activity_add_record);
subjectEditText = (EditText) findViewById(R.id.subject_edittext);
descEditText = (EditText) findViewById(R.id.description_edittext);
addTodoBtn = (Button) findViewById(R.id.add_record);
dbController = new SQLController(this);
dbController.open();
addTodoBtn.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.add_record:
final String name = subjectEditText.getText().toString();
final String desc = descEditText.getText().toString();
dbController.insert(name, desc);
Intent main = new Intent(AddTodoActivity.this,
TodoListActivity.class)
.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(main);
break;
default:
break;
}
}
}
ModifyTodoActivity.java
package com.javatechig.todo;
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 ModifyTodoActivity extends Activity implements OnClickListener {
private EditText titleText;
private Button updateBtn, deleteBtn;
private long _id;
private SQLController dbController;
private EditText descText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setTitle("Modify Record");
setContentView(R.layout.activity_modify_record);
dbController = new SQLController(this);
dbController.open();
titleText = (EditText) findViewById(R.id.subject_edittext);
descText = (EditText) findViewById(R.id.description_edittext);
updateBtn = (Button) findViewById(R.id.btn_update);
deleteBtn = (Button) findViewById(R.id.btn_delete);
Intent intent = getIntent();
String id = intent.getStringExtra("id");
String name = intent.getStringExtra("title");
String desc = intent.getStringExtra("desc");
_id = Long.parseLong(id);
titleText.setText(name);
descText.setText(desc);
updateBtn.setOnClickListener(this);
deleteBtn.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btn_update:
String title = titleText.getText().toString();
String desc = descText.getText().toString();
dbController.update(_id, title, desc);
this.returnHome();
break;
case R.id.btn_delete:
dbController.delete(_id);
this.returnHome();
break;
}
}
public void returnHome() {
Intent home_intent = new Intent(getApplicationContext(),
TodoListActivity.class)
.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(home_intent);
}
}
