Android login/registration with shared preferences

问题:

I'm new to Android. I'm doing an app for an university exam. I have to do an application for a travel agency. I'd like to manage the user session with shared preferences in order to save basic information and the eventually travels that the user booked. I can't find an example on the web that combine the registration and login forms. I wrote this code but it's not working. It doesn't show any error. I think what I wrote it's not logic. I'd like to register first and login with the information I gave in the registration form. Thank you for your help.

This is my Login.java:

package com.example.trip;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class Login extends ActionBarActivity {

public static android.content.SharedPreferences SharedPreferences = null;

private static final String PREFER_NAME = null;

Button buttonLogin;

EditText txtUsername, txtPassword;

// User Session Manager Class
UserSession session;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login); 

    Button switchButton = (Button)findViewById(R.id.buttonReg);
    switchButton.setOnClickListener (new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            Intent intent=new Intent(Login.this, Reg.class);
            startActivity(intent);

        }
    });


    // User Session Manager
    session = new UserSession(getApplicationContext());                

    // get Email, Password input text
    txtUsername = (EditText) findViewById(R.id.txtUsername);
    txtPassword = (EditText) findViewById(R.id.txtPassword); 

    Toast.makeText(getApplicationContext(), 
            "User Login Status: " + session.isUserLoggedIn(), 
            Toast.LENGTH_LONG).show();


    // User Login button
    buttonLogin = (Button) findViewById(R.id.buttonLogin);

    SharedPreferences = getSharedPreferences(PREFER_NAME, Context.MODE_PRIVATE);


    // Login button click event
    buttonLogin.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {

            // Get username, password from EditText
            String username = txtUsername.getText().toString();
            String password = txtPassword.getText().toString();

            // Validate if username, password is filled             
            if(username.trim().length() > 0 && password.trim().length() > 0){

                if (SharedPreferences.contains("name"))
                  {
                     String uName = (SharedPreferences).getString("name", "");

                  }

                  if (SharedPreferences.contains("email"))
                  {
                     String uEmail = (SharedPreferences).getString("email", "");

                  }

                            Object uName = null;
                            Object uEmail = null;
                            if(username.equals(uName) && password.equals(uEmail)){

                                session.createUserLoginSession(uName, 
                                   uEmail);

                                // Starting MainActivity
                                Intent i = new  Intent(getApplicationContext(),MainActivity.class);
                                i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

                                // Add new Flag to start new Activity
                                i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                                startActivity(i);

                                finish();

                            }else{

                                // username / password doesn't match&
                                Toast.makeText(getApplicationContext(), 
                                  "Username/Password is incorrect",
                                        Toast.LENGTH_LONG).show();

                            }               
                        }else{

                            // user didn't entered username or password
                            Toast.makeText(getApplicationContext(), 
                                 "Please enter username and password",
                                      Toast.LENGTH_LONG).show();

                        }

                    }
                });
}
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = new MenuInflater(this);
        inflater.inflate(R.menu.main, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();
        switch (id) {
        case R.id.MENU_1:
            Intent intent1 = new Intent(this, Login.class);
            this.startActivity(intent1);
            break;
        case R.id.MENU_2:
            Intent intent2 = new Intent(this, MainActivity.class);
            this.startActivity(intent2);
        break;
        default:
            return super.onOptionsItemSelected(item);
        }

        return true;
    }       
}

This is the UserSession.java:

package com.example.trip;

import java.util.HashMap;

import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;

public class UserSession {
// Shared Preferences reference
SharedPreferences pref;

// Editor reference for Shared preferences
Editor editor;

// Context
Context _context;

// Shared preferences mode
int PRIVATE_MODE = 0;

// Shared preferences file name
public static final String PREFER_NAME = "AndroidExamplePref";

// All Shared Preferences Keys
public static final String IS_USER_LOGIN = "IsUserLoggedIn";

// User name (make variable public to access from outside)
public static final String KEY_NAME = "name";

// Email address (make variable public to access from outside)
public static final String KEY_EMAIL = "email";

// Constructor
public UserSession(Context context){
    this._context = context;
    pref = _context.getSharedPreferences(PREFER_NAME, PRIVATE_MODE);
    editor = pref.edit();
}

//Create login session
public void createUserLoginSession(Object uName, Object uEmail){
    // Storing login value as TRUE
    editor.putBoolean(IS_USER_LOGIN, true);

    // Storing name in preferences
    editor.putString(KEY_NAME, (String) uName);

    // Storing email in preferences
    editor.putString(KEY_EMAIL, (String) uEmail);

    // commit changes
    editor.commit();
}   

/**
 * Check login method will check user login status
 * If false it will redirect user to login page
 * Else do anything
 * */
public boolean checkLogin(){
    // Check login status
    if(!this.isUserLoggedIn()){

        // user is not logged in redirect him to Login Activity
        Intent i = new Intent(_context, Login.class);

        // Closing all the Activities from stack
        i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

        // Add new Flag to start new Activity
        i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

        // Staring Login Activity
        _context.startActivity(i);

        return true;
    }
    return false;
}



/**
 * Get stored session data
 * */
public HashMap<String, String> getUserDetails(){

    //Use hashmap to store user credentials
    HashMap<String, String> user = new HashMap<String, String>();

    // user name
    user.put(KEY_NAME, pref.getString(KEY_NAME, null));

    // user email id
    user.put(KEY_EMAIL, pref.getString(KEY_EMAIL, null));

    // return user
    return user;
}

/**
 * Clear session details
 * */
public void logoutUser(){

    // Clearing all user data from Shared Preferences
    editor.clear();
    editor.commit();

    // After logout redirect user to MainActivity
    Intent i = new Intent(_context, MainActivity.class);

    // Closing all the Activities
    i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

    // Add new Flag to start new Activity
    i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

    // Staring Login Activity
    _context.startActivity(i);
}


// Check for login
public boolean isUserLoggedIn(){
    return pref.getBoolean(IS_USER_LOGIN, false);
}
}

This is the MainActivity.java:

public class MainActivity extends ActionBarActivity {

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

public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = new MenuInflater(this);
    inflater.inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
    switch (id) {
    case R.id.MENU_1:
        Intent intent1 = new Intent(this, Login.class);
        this.startActivity(intent1);
        break;
    case R.id.MENU_2:
        Intent intent2 = new Intent(this, MainActivity.class);
        this.startActivity(intent2);
    break;
    default:
        return super.onOptionsItemSelected(item);
    }

    return true;
}
}

This is my Reg.java:

package com.example.trip;

import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import android.view.View.OnClickListener;

public class Reg extends ActionBarActivity {

SharedPreferences SharedPreferences;
Editor editor;
Button buttonReg2;
EditText txtUsername, txtPassword, txtEmail;  
UserSession session;

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.reg);

txtUsername = (EditText) findViewById(R.id.Name);
txtPassword = (EditText) findViewById(R.id.txtPassword);
txtEmail = (EditText) findViewById(R.id.Email);
buttonReg2 = (Button) findViewById(R.id.buttonReg2);

// creating an shared Preference file for the information to be stored
// first argument is the name of file and second is the mode, 0 is private mode

SharedPreferences = getSharedPreferences("Reg", 0);
// get editor to edit in file
editor = SharedPreferences.edit();

buttonReg2.setOnClickListener(new View.OnClickListener() {

    public void onClick (View v) {
    String name = txtUsername.getText().toString();
    String email = txtEmail.getText().toString();
    String pass = txtPassword.getText().toString();

    if(txtUsername.getText().length()<=0){
        Toast.makeText(Reg.this, "Enter name", Toast.LENGTH_SHORT).show();
    }
    else if( txtEmail.getText().length()<=0){
        Toast.makeText(Reg.this, "Enter email", Toast.LENGTH_SHORT).show();
    }
    else if( txtPassword.getText().length()<=0){
        Toast.makeText(Reg.this, "Enter password", Toast.LENGTH_SHORT).show();
    }
    else{

    // as now we have information in string. Lets stored them with the help of editor
    editor.putString("Name", name);
    editor.putString("Email",email);
    editor.putString("txtPassword",pass);
    editor.commit();}   // commit the values

    // after saving the value open next activity
    Intent ob = new Intent(Reg.this, Login.class);
    startActivity(ob);

    }
});
}

    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = new MenuInflater(this);
        inflater.inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();
        switch (id) {
        case R.id.MENU_1:
            Intent intent1 = new Intent(this, Login.class);
            this.startActivity(intent1);
            break;
        case R.id.MENU_2:
            Intent intent2 = new Intent(this, MainActivity.class);
            this.startActivity(intent2);
        break;
        default:
            return super.onOptionsItemSelected(item);
        }

        return true;
    }
 }

The XML code of the MainActivity:

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="top"
    android:shrinkColumns="0"
    android:stretchColumns="1" >

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="fill_horizontal|center_vertical" >

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="fill_horizontal|center_vertical"
            android:text="@string/destinazione" />

        <EditText
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:inputType="text" />
    </TableRow>

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="fill_horizontal|center_vertical" >

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="fill_horizontal|center_vertical"
            android:text="@string/checkin" />

        <EditText
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:inputType="date" />
    </TableRow>

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="fill_horizontal|center_vertical" >

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="fill_horizontal|center_vertical"
            android:text="@string/checkout" />

        <EditText
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:inputType="date" />
    </TableRow>

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="fill_horizontal|center_vertical" >

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="fill_horizontal|center_vertical"
            android:text="@string/viaggiatori" />

        <EditText
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:inputType="number" />
    </TableRow>

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="fill_horizontal|center_vertical" >

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="fill_horizontal|center_vertical"
            android:text="@string/stelle" />

        <Spinner
            android:id="@+id/spinner"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:entries="@array/stelle"/>
    </TableRow>

    <Button
        android:id="@+id/buttonFind"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/buttonFind" />

  </TableLayout>

The XML code for the login form:

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="top"
android:shrinkColumns="0"
android:stretchColumns="1" >

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="fill_horizontal|center_vertical" >

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="fill_horizontal|center_vertical"
            android:text="@string/txtUsername" />

        <EditText
            android:id="@+id/txtUsername"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:inputType="text" />
    </TableRow>

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="fill_horizontal|center_vertical" >

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="fill_horizontal|center_vertical"
            android:text="@string/txtPassword" />

        <EditText
            android:id="@+id/txtPassword"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:inputType="textPassword" />
    </TableRow>

    <Button
        android:id="@+id/buttonLogin"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/buttonLogin" />

    <Button
        android:id="@+id/buttonReg"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/buttonReg" />

 </TableLayout>

This is the XML code for the registration form:

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="top"
android:shrinkColumns="0"
android:stretchColumns="1" >

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="fill_horizontal|center_vertical" >

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="fill_horizontal|center_vertical"
            android:text="@string/Name" />

        <EditText
            android:id="@+id/Name"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:inputType="text" />
    </TableRow>

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="fill_horizontal|center_vertical" >

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="fill_horizontal|center_vertical"
            android:text="@string/Email" />

        <EditText
            android:id="@+id/Email"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:inputType="textEmailAddress" />
    </TableRow>


    <TableRow
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="fill_horizontal|center_vertical" >

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="fill_horizontal|center_vertical"
            android:text="@string/txtPassword" />

        <EditText
            android:id="@+id/txtPassword"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:inputType="textPassword" />
    </TableRow>

    <Button
        android:id="@+id/buttonReg2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/buttonReg2" />

 </TableLayout>

回答1:

This is working code, try it.

MainActivity.java

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

public class MainActivity extends ActionBarActivity {

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

public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = new MenuInflater(this);
    inflater.inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
    switch (id) {
    case R.id.menu1:
        Intent intent1 = new Intent(this, Login.class);
        this.startActivity(intent1);
        break;
    case R.id.menu2:
        Intent intent2 = new Intent(this, MainActivity.class);
        this.startActivity(intent2);
    break;
    default:
        return super.onOptionsItemSelected(item);
    }

    return true;
}
}

Reg.java

import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class Reg extends ActionBarActivity {

SharedPreferences sharedPreferences;
Editor editor;
Button buttonReg2;
EditText txtUsername, txtPassword, txtEmail;  
UserSession session;

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.reg);

txtUsername = (EditText) findViewById(R.id.Name);
txtPassword = (EditText) findViewById(R.id.txtPassword);
txtEmail = (EditText) findViewById(R.id.Email);
buttonReg2 = (Button) findViewById(R.id.buttonReg2);

// creating an shared Preference file for the information to be stored
// first argument is the name of file and second is the mode, 0 is private mode

sharedPreferences = getApplicationContext().getSharedPreferences("Reg", 0);
// get editor to edit in file
editor = sharedPreferences.edit();

buttonReg2.setOnClickListener(new View.OnClickListener() {

    public void onClick (View v) {
    String name = txtUsername.getText().toString();
    String email = txtEmail.getText().toString();
    String pass = txtPassword.getText().toString();

    if(txtUsername.getText().length()<=0){
        Toast.makeText(Reg.this, "Enter name", Toast.LENGTH_SHORT).show();
    }
    else if( txtEmail.getText().length()<=0){
        Toast.makeText(Reg.this, "Enter email", Toast.LENGTH_SHORT).show();
    }
    else if( txtPassword.getText().length()<=0){
        Toast.makeText(Reg.this, "Enter password", Toast.LENGTH_SHORT).show();
    }
    else{

    // as now we have information in string. Lets stored them with the help of editor
    editor.putString("Name", name);
    editor.putString("Email",email);
    editor.putString("txtPassword",pass);
    editor.commit();}   // commit the values

    // after saving the value open next activity
    Intent ob = new Intent(Reg.this, Login.class);
    startActivity(ob);

    }
});
}

    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = new MenuInflater(this);
        inflater.inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();
        switch (id) {
        case R.id.menu1:
            Intent intent1 = new Intent(this, Login.class);
            this.startActivity(intent1);
            break;
        case R.id.menu2:
            Intent intent2 = new Intent(this, MainActivity.class);
            this.startActivity(intent2);
        break;
        default:
            return super.onOptionsItemSelected(item);
        }

        return true;
    }
 }

Login.java

import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class Login extends ActionBarActivity {

//public static android.content.SharedPreferences SharedPreferences = null;

private static final String PREFER_NAME = "Reg";

Button buttonLogin;

EditText txtUsername, txtPassword;

// User Session Manager Class
UserSession session;

private SharedPreferences sharedPreferences;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login); 

    Button switchButton = (Button)findViewById(R.id.buttonReg);
    switchButton.setOnClickListener (new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            Intent intent=new Intent(Login.this, Reg.class);
            startActivity(intent);

        }
    });


    // User Session Manager
    session = new UserSession(getApplicationContext());                

    // get Email, Password input text
    txtUsername = (EditText) findViewById(R.id.txtUsername);
    txtPassword = (EditText) findViewById(R.id.txtPassword); 

    Toast.makeText(getApplicationContext(), 
            "User Login Status: " + session.isUserLoggedIn(), 
            Toast.LENGTH_LONG).show();


    // User Login button
    buttonLogin = (Button) findViewById(R.id.buttonLogin);

    sharedPreferences = getSharedPreferences(PREFER_NAME, Context.MODE_PRIVATE);


    // Login button click event
    buttonLogin.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {

            // Get username, password from EditText
            String username = txtUsername.getText().toString();
            String password = txtPassword.getText().toString();

            // Validate if username, password is filled             
            if(username.trim().length() > 0 && password.trim().length() > 0){
                    String uName = null;
                    String uPassword =null;

                if (sharedPreferences.contains("Name"))
                  {
                     uName = sharedPreferences.getString("Name", "");

                  }

                  if (sharedPreferences.contains("txtPassword"))
                  {
                     uPassword = sharedPreferences.getString("txtPassword", "");

                  }

                           // Object uName = null;
                           // Object uEmail = null;
                            if(username.equals(uName) && password.equals(uPassword)){

                                session.createUserLoginSession(uName, 
                                   uPassword);

                                // Starting MainActivity
                                Intent i = new  Intent(getApplicationContext(),MainActivity.class);
                                i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

                                // Add new Flag to start new Activity
                                i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                                startActivity(i);

                                finish();

                            }else{

                                // username / password doesn't match&
                                Toast.makeText(getApplicationContext(), 
                                  "Username/Password is incorrect",
                                        Toast.LENGTH_LONG).show();

                            }               
                        }else{

                            // user didn't entered username or password
                            Toast.makeText(getApplicationContext(), 
                                 "Please enter username and password",
                                      Toast.LENGTH_LONG).show();

                        }

                    }
                });
}
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = new MenuInflater(this);
        inflater.inflate(R.menu.main, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();
        switch (id) {
        case R.id.menu1:
            Intent intent1 = new Intent(this, Login.class);
            this.startActivity(intent1);
            break;
        case R.id.menu2:
            Intent intent2 = new Intent(this, MainActivity.class);
            this.startActivity(intent2);
        break;
        default:
            return super.onOptionsItemSelected(item);
        }

        return true;
    }       
}

UserSession.java

package com.example.tripmanager;

import java.util.HashMap;

import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;

public class UserSession {
// Shared Preferences reference
SharedPreferences pref;

// Editor reference for Shared preferences
Editor editor;

// Context
Context _context;

// Shared preferences mode
int PRIVATE_MODE = 0;

// Shared preferences file name
public static final String PREFER_NAME = "Reg";

// All Shared Preferences Keys
public static final String IS_USER_LOGIN = "IsUserLoggedIn";

// User name (make variable public to access from outside)
public static final String KEY_NAME = "Name";

// Email address (make variable public to access from outside)
public static final String KEY_EMAIL = "Email";

// password
public static final String KEY_PASSWORD = "txtPassword";

// Constructor
public UserSession(Context context){
    this._context = context;
    pref = _context.getSharedPreferences(PREFER_NAME, PRIVATE_MODE);
    editor = pref.edit();
}

//Create login session
public void createUserLoginSession(String uName, String uPassword){
    // Storing login value as TRUE
    editor.putBoolean(IS_USER_LOGIN, true);

    // Storing name in preferences
    editor.putString(KEY_NAME, uName);

    // Storing email in preferences
    editor.putString(KEY_EMAIL,  uPassword);

    // commit changes
    editor.commit();
}   

/**
 * Check login method will check user login status
 * If false it will redirect user to login page
 * Else do anything
 * */
public boolean checkLogin(){
    // Check login status
    if(!this.isUserLoggedIn()){

        // user is not logged in redirect him to Login Activity
        Intent i = new Intent(_context, Login.class);

        // Closing all the Activities from stack
        i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

        // Add new Flag to start new Activity
        i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

        // Staring Login Activity
        _context.startActivity(i);

        return true;
    }
    return false;
}



/**
 * Get stored session data
 * */
public HashMap<String, String> getUserDetails(){

    //Use hashmap to store user credentials
    HashMap<String, String> user = new HashMap<String, String>();

    // user name
    user.put(KEY_NAME, pref.getString(KEY_NAME, null));

    // user email id
    user.put(KEY_EMAIL, pref.getString(KEY_EMAIL, null));

    // return user
    return user;
}

/**
 * Clear session details
 * */
public void logoutUser(){

    // Clearing all user data from Shared Preferences
    editor.clear();
    editor.commit();

    // After logout redirect user to MainActivity
    Intent i = new Intent(_context, MainActivity.class);

    // Closing all the Activities
    i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

    // Add new Flag to start new Activity
    i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

    // Staring Login Activity
    _context.startActivity(i);
}


// Check for login
public boolean isUserLoggedIn(){
    return pref.getBoolean(IS_USER_LOGIN, false);
}
}

回答2:

This code working in my project,must try it

Use this code after login validation to store login value

  String Username = textInputEditTextEmail.getText().toString();
        String Password = textInputEditTextPassword.getText().toString();
        final SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(this);
        SharedPreferences.Editor editor = sharedPref.edit();
        editor.putBoolean("Registered", true);
        editor.putString("Username", Username);
        editor.putString("Password", Password);
        editor.apply();

Create new empty activity and copy this code

  Boolean Registered;
    final SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(this);
    Registered = sharedPref.getBoolean("Registered", false);

    if (!Registered)
    {
        startActivity(new Intent(this,Splash.class));
    }else {
        startActivity(new Intent(this,MainActivity.class));
    }

In Menifest file copy the intent-filter code in newly created empty file for initial access.

For Logout, Create any button copy this code in click on listener

  SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
        SharedPreferences.Editor editor = preferences.edit();
        editor.clear();
        editor.commit();
        Intent i = new Intent(MainActivity.this,Login.class);
        startActivity(i);