Android系统。如何保存用户名和密码后，应用程序被关闭？

我在写有登录信息（用户名和密码）的应用程序。
我想使它以便当用户关闭应用程序并再次启动后，他/她不必再次输入他/她的用户名和密码。

I am writing an application with login details (username and password).
I want to make it so that when the user closes the application and starts it again later he/she doesn't have to enter his/her user name and password again.

因此​​，这里是我的code为止。它似乎没有记住密码或用户名，不幸的是我：

So here is my code so far. It doesn't seem to remember the password nor the username, unfortunately for me:

protected void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    mPrefs = getSharedPreferences(PREFS, 0);
    final CheckBox rememberMeCbx = (CheckBox)findViewById(R.id.saveLoginCheckBox);

    boolean rememberMe = mPrefs.getBoolean("rememberMe", false);



    if (android.os.Build.VERSION.SDK_INT > 9)
    {
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy);
    }
    mXmlRpcClient = new XMLRPCClient(mXmlRpcUri);

    // Set up the login form.
    //mUsername = getIntent().getStringExtra(EXTRA_EMAIL);
    mUsernameView = (EditText) findViewById(R.id.username);
    mUsernameView.setText(mUsername);

    mPasswordView = (EditText) findViewById(R.id.password);
    mPasswordView.setOnEditorActionListener(new TextView.OnEditorActionListener() {
                @Override
                public boolean onEditorAction(TextView textView, int id,
                        KeyEvent keyEvent) {
                    if (id == R.id.login || id == EditorInfo.IME_NULL) {
                        attemptLogin();
                        return true;
                    }
                    return false;
                }
            });

    mLoginFormView = findViewById(R.id.login_form);
    mLoginStatusView = findViewById(R.id.login_status);
    mLoginStatusMessageView = (TextView) findViewById(R.id.login_status_message);

    findViewById(R.id.sign_in_button).setOnClickListener
    (
            new View.OnClickListener()
            {
                @Override
                public void onClick(View view) 
                {
                    if(rememberMeCbx.isChecked())
                    {
                        attemptLogin(); //function to check if fields are filled correctly
                        saveLoginDetails();
                    }
                    else
                    {
                        attemptLogin();
                        removeLoginDetails();
                    }

                }
            });

    if(rememberMe == true)
    {
        //get previously stored login details
        String login = mPrefs.getString("mUsername", null);
        String upass = mPrefs.getString("mPassword", null);

        if(login != null && upass != null)
        {
            //fill input boxes with stored login and pass
            EditText loginEbx = (EditText)findViewById(R.id.username);
            EditText passEbx = (EditText)findViewById(R.id.password);
            loginEbx.setText(login);
            passEbx.setText(upass);

            //set the check box to 'checked'                
            rememberMeCbx.setChecked(true);
        }
    }
}



/**
 * Represents an asynchronous login/registration task used to authenticate
 * the user.
 */
public class UserLoginTask extends AsyncTask<Void, Void, Boolean> {
    @Override
    protected Boolean doInBackground(Void... params) {
        try {
            mSessionID = (String)mXmlRpcClient.call(mLoginFuncName, mUsername, mPassword);
            return true;
        } catch (Exception e) {
            return false;
        }
    }

    @Override
    protected void onPostExecute(final Boolean success) {
        mAuthTask = null;
        showProgress(false);

        if (success) {
            finish();
            Intent intent = new Intent(LoginActivity.this, MainWindow.class);
            intent.putExtra("SessionID", mSessionID);
            intent.putExtra("XmlRpcUrl", mXmlRpcUrl);
            intent.putExtra("LoginFuncName", mLoginFuncName);
            intent.putExtra("LogoutFuncName", mLogoutFuncName);
            intent.putExtra("GetDevicesFuncName", mGetDevicesFuncName);
            intent.putExtra("SendPositionFuncName", mSendPositionFuncName);
            intent.putExtra("GetSavedTripFunc", mGetSavedTripFunc);             
            startActivity(intent);
        } else {
            mPasswordView
                    .setError(getString(R.string.error_incorrect_password));
            mPasswordView.requestFocus();
        }
    }


}

private void saveLoginDetails()
{
    //fill input boxes with stored login and pass
    EditText loginEbx = (EditText)findViewById(R.id.username);
    EditText passEbx = (EditText)findViewById(R.id.password);
    String login = loginEbx.getText().toString();
    String upass = passEbx.getText().toString();

    Editor e = mPrefs.edit();
    e.putBoolean("rememberMe", true);
    e.putString("login", login);
    e.putString("password", upass);
    e.commit();
}

private void removeLoginDetails()
{
    Editor e = mPrefs.edit();
    e.putBoolean("rememberMe", false);
    e.remove("login");
    e.remove("password");
    e.commit();
}

}

你能告诉我什么是错我的code，我该如何改进它，使用户名和密码保存和检索后，该应用程序被关闭并重新打开？

Can you tell me what is wrong with my code and how can I improve it so that the user name and password are saved and retrieved after the application is closed and opened again?