Android Tutorials for Beginners
In this post we will develop an app in which a user can perform following task1: User Can Create Account
2: User Can log in
we will use and learn following this in this Post
Customized Dialog: Here we have used Customized Dialog for User Login.
Creating DataBase: Here we have created database for Storing UserName and Password.
Writing functions for Inserting, Deleting, Updating and querying a Datbase.
we have create a Table with following Fields :
USERNAME : to store the user name.
PASSWORD: to store the password of User
Table Name is LOGIN
The Code is well commented , just go through , you will understand easily.
List of XMLs Used.
main.xml : main screen
signup.xml : to create a new account
login.xml : to login
main.xml
<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"
android:gravity="center_vertical" >
<Button
android:id="@+id/buttonSignIN"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Sign IN"
android:onClick="signIn"/>
<Button
android:id="@+id/buttonSignUP"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Sign UP" />
</LinearLayout>
signup.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:gravity="center_vertical" >
<EditText
android:id="@+id/editTextUserName"
android:hint="User Name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
<requestFocus />
</EditText>
<EditText
android:id="@+id/editTextPassword"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:hint="Password"
android:inputType="textPassword" />
<EditText
android:id="@+id/editTextConfirmPassword"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:hint="Confirm Password"
android:inputType="textPassword" />
<Button
android:id="@+id/buttonCreateAccount"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Create Account"
android:layout_marginBottom="60dp" />
</LinearLayout>
login.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" >
<EditText
android:id="@+id/editTextUserNameToLogin"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="User Name"
android:ems="10" >
<requestFocus />
</EditText>
<EditText
android:id="@+id/editTextPasswordToLogin"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:inputType="textPassword"
android:hint="Password" />
<Button
android:id="@+id/buttonSignIn"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Sign In" />
</LinearLayout>
Activities:
1: HomeActivity.java
public class HomeActivity extends Activity
{
Button btnSignIn,btnSignUp;
LoginDataBaseAdapter loginDataBaseAdapter;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// create the instance of Databse
loginDataBaseAdapter=new LoginDataBaseAdapter(this);
loginDataBaseAdapter=loginDataBaseAdapter.open();
// Get The Refference Of Buttons
btnSignIn=(Button)findViewById(R.id.buttonSignIN);
btnSignUp=(Button)findViewById(R.id.buttonSignUP);
// Set OnClick Listener on SignUp button
btnSignUp.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
/// Create Intent for SignUpActivity abd Start The Activity
Intent intentSignUP=new Intent(getApplicationContext(),SignUPActivity.class);
startActivity(intentSignUP);
}
});
}
// Methos to handleClick Event of Sign In Button
public void signIn(View V)
{
final Dialog dialog = new Dialog(HomeActivity.this);
dialog.setContentView(R.layout.login);
dialog.setTitle("Login");
// get the Refferences of views
final EditText editTextUserName=(EditText)dialog.findViewById(R.id.editTextUserNameToLogin);
final EditText editTextPassword=(EditText)dialog.findViewById(R.id.editTextPasswordToLogin);
Button btnSignIn=(Button)dialog.findViewById(R.id.buttonSignIn);
// Set On ClickListener
btnSignIn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
// get The User name and Password
String userName=editTextUserName.getText().toString();
String password=editTextPassword.getText().toString();
// fetch the Password form database for respective user name
String storedPassword=loginDataBaseAdapter.getSinlgeEntry(userName);
// check if the Stored password matches with Password entered by user
if(password.equals(storedPassword))
{
Toast.makeText(HomeActivity.this, "Login Successfull", Toast.LENGTH_LONG).show();
dialog.dismiss();
}
else
{
Toast.makeText(HomeActivity.this, "User Name and Does Not Matches", Toast.LENGTH_LONG).show();
}
}
});
dialog.show();
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
// Close The Database
loginDataBaseAdapter.close();
}
}
2: SignUpActivity.java
public class SignUPActivity extends Activity
{
EditText editTextUserName,editTextPassword,editTextConfirmPassword;
Button btnCreateAccount;
LoginDataBaseAdapter loginDataBaseAdapter;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.signup);
// get Instance of Database Adapter
loginDataBaseAdapter=new LoginDataBaseAdapter(this);
loginDataBaseAdapter=loginDataBaseAdapter.open();
// Get Refferences of Views
editTextUserName=(EditText)findViewById(R.id.editTextUserName);
editTextPassword=(EditText)findViewById(R.id.editTextPassword);
editTextConfirmPassword=(EditText)findViewById(R.id.editTextConfirmPassword);
btnCreateAccount=(Button)findViewById(R.id.buttonCreateAccount);
btnCreateAccount.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
String userName=editTextUserName.getText().toString();
String password=editTextPassword.getText().toString();
String confirmPassword=editTextConfirmPassword.getText().toString();
// check if any of the fields are vaccant
if(userName.equals("")||password.equals("")||confirmPassword.equals(""))
{
Toast.makeText(getApplicationContext(), "Field Vaccant", Toast.LENGTH_LONG).show();
return;
}
// check if both password matches
if(!password.equals(confirmPassword))
{
Toast.makeText(getApplicationContext(), "Password Does Not Matches", Toast.LENGTH_LONG).show();
return;
}
else
{
// Save the Data in Database
loginDataBaseAdapter.insertEntry(userName, password);
Toast.makeText(getApplicationContext(), "Account Successfully Created ", Toast.LENGTH_LONG).show();
}
}
});
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
loginDataBaseAdapter.close();
}
}
3: DataBaseHelper.java
package com.example.login;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class DataBaseHelper extends SQLiteOpenHelper
{
public DataBaseHelper(Context context, String name,CursorFactory factory, int version)
{
super(context, name, factory, version);
}
// Called when no database exists in disk and the helper class needs
// to create a new one.
@Override
public void onCreate(SQLiteDatabase _db)
{
_db.execSQL(LoginDataBaseAdapter.DATABASE_CREATE);
}
// Called when there is a database version mismatch meaning that the version
// of the database on disk needs to be upgraded to the current version.
@Override
public void onUpgrade(SQLiteDatabase _db, int _oldVersion, int _newVersion)
{
// Log the version upgrade.
Log.w("TaskDBAdapter", "Upgrading from version " +_oldVersion + " to " +_newVersion + ", which will destroy all old data");
// Upgrade the existing database to conform to the new version. Multiple
// previous versions can be handled by comparing _oldVersion and _newVersion
// values.
// The simplest case is to drop the old table and create a new one.
_db.execSQL("DROP TABLE IF EXISTS " + "TEMPLATE");
// Create a new one.
onCreate(_db);
}
}
4: LoginDataBaseAdapter.java
public class LoginDataBaseAdapter
{
static final String DATABASE_NAME = "login.db";
static final int DATABASE_VERSION = 1;
public static final int NAME_COLUMN = 1;
// TODO: Create public field for each column in your table.
// SQL Statement to create a new database.
static final String DATABASE_CREATE = "create table "+"LOGIN"+
"( " +"ID"+" integer primary key autoincrement,"+ "USERNAME text,PASSWORD text); ";
// Variable to hold the database instance
public SQLiteDatabase db;
// Context of the application using the database.
private final Context context;
// Database open/upgrade helper
private DataBaseHelper dbHelper;
public LoginDataBaseAdapter(Context _context)
{
context = _context;
dbHelper = new DataBaseHelper(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Method to openthe Database
public LoginDataBaseAdapter open() throws SQLException
{
db = dbHelper.getWritableDatabase();
return this;
}
// Method to close the Database
public void close()
{
db.close();
}
// method returns an Instance of the Database
public SQLiteDatabase getDatabaseInstance()
{
return db;
}
// method to insert a record in Table
public void insertEntry(String userName,String password)
{
ContentValues newValues = new ContentValues();
// Assign values for each column.
newValues.put("USERNAME", userName);
newValues.put("PASSWORD",password);
// Insert the row into your table
db.insert("LOGIN", null, newValues);
Toast.makeText(context, "User Info Saved", Toast.LENGTH_LONG).show();
}
// method to delete a Record of UserName
public int deleteEntry(String UserName)
{
String where="USERNAME=?";
int numberOFEntriesDeleted= db.delete("LOGIN", where, new String[]{UserName}) ;
Toast.makeText(context, "Number fo Entry Deleted Successfully : "+numberOFEntriesDeleted, Toast.LENGTH_LONG).show();
return numberOFEntriesDeleted;
}
// method to get the password of userName
public String getSinlgeEntry(String userName)
{
Cursor cursor=db.query("LOGIN", null, " USERNAME=?", new String[]{userName}, null, null, null);
if(cursor.getCount()<1) // UserName Not Exist
return "NOT EXIST";
cursor.moveToFirst();
String password= cursor.getString(cursor.getColumnIndex("PASSWORD"));
return password;
}
// Method to Update an Existing Record
public void updateEntry(String userName,String password)
{
// create object of ContentValues
ContentValues updatedValues = new ContentValues();
// Assign values for each Column.
updatedValues.put("USERNAME", userName);
updatedValues.put("PASSWORD",password);
String where="USERNAME = ?";
db.update("LOGIN",updatedValues, where, new String[]{userName});
}
}
