Android fill up text fields

Question

I have no idea, which factor may cause this problem, as even after debugging, still cannot figure it out. The problem is, that after start of application, I am trying to fill up text fields for login and password with saved data from previous login. However I cannot get reference to TextFields :/ It always get's null, and dunno why. What I have so far is.

public class Login extends ActionBarActivity {

private String SHARED_PREFS_KEY = "SBJP";
private String LOGIN_KEY = "login";
private String PASS_KEY = "pass";

private EditText userName;
private EditText password;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);
    PlaceholderFragment phFrag = new PlaceholderFragment();

    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, phFrag)
                .commit();
    }

    loadPreferences(phFrag);

}


@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.login, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_login, container, false);
        return rootView;
    }
}

/**
 * Handles login action
 */
public void loginClick(View v){
    this.userName = (EditText) findViewById(R.id.login_screen_tf_login);
    this.password = (EditText) findViewById(R.id.login_screen_tf_password);

    String userNameStr = userName.getText().toString();
    String passStr = password.getText().toString();

    //Log.d("SB", userNameStr+":"+passStr);
    SharedPreferences prefs = getSharedPreferences(SHARED_PREFS_KEY, MODE_PRIVATE);
    Editor editor = prefs.edit();

    editor.putString(PASS_KEY, passStr);
    editor.putString(LOGIN_KEY, userNameStr);
    editor.commit();
}

/**
 * Handles creating new account
 */
public void createNewAccountClick(View v){
    Log.d("SB", "Here comes account creation");
}

private void loadPreferences(PlaceholderFragment rootView){
    SharedPreferences prefs = getSharedPreferences(SHARED_PREFS_KEY, MODE_PRIVATE);
    String loginStr = prefs.getString(LOGIN_KEY, null);
    String passStr = prefs.getString(PASS_KEY, null);

    this.userName = (EditText) rootView.getView().findViewById(R.id.login_screen_tf_login);
    this.password = (EditText) rootView.getView().findViewById(R.id.login_screen_tf_password);

    Log.d("SB","Login/sn:"+loginStr+passStr);

    if(loginStr != null && userName != null){
        userName.setText(loginStr);
    }
    if(passStr != null && password != null){
        password.setText(passStr);
    }

}

}

Does anybody know, why do I always get userName and password variables as null in loadPreferences method? In loginClick method it works fine :/ ...

Thanks in advance

Answer 1

this.userName = (EditText) findViewById(R.id.login_screen_tf_login);
this.password = (EditText) findViewById(R.id.login_screen_tf_password);

Here you need to get a root view of a fragment, but inside a code of your PlaceholderFragment class:

userName = (EditText) getView().findViewById(R.id.login_screen_tf_login);
password = (EditText) getView().findViewById(R.id.login_screen_tf_password);

http://developer.android.com/reference/android/app/Fragment.html#getView()

Of course we suggest that login_screen_tf_login and login_screen_tf_login EditText-s is located in your fragment_login layout.

ADDITION:

You can redesign PlaceholderFragment as follow:

public static class PlaceholderFragment extends Fragment {

private String login;
private String password;

public void setAuthData(String login, String password){ this.login = login; this.password = password; }

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_login, container, false);

    EditText userName = (EditText) rootView.findViewById(R.id.login_screen_tf_login);
    userName.setText(login); 
    EditText passwordET = (EditText) rootView.findViewById(R.id.login_screen_tf_password); 
    passwordET.setText(password);
    return rootView;
}
}

And use PlaceholderFragment class as follow:

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

    SharedPreferences prefs = getSharedPreferences(SHARED_PREFS_KEY, MODE_PRIVATE);
    String login = prefs.getString(LOGIN_KEY, null);
    String password = prefs.getString(PASS_KEY, null);

    PlaceholderFragment phFrag = new PlaceholderFragment();
    phFrag.setAuthData(login, password);

    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
            .add(R.id.container, phFrag)
            .commit();
    }
 }

Answer 2

Since the TextViews are in the layout for PlaceholderFragment, their logic should be there too. You can technically use findViewById to get the fragment's views from the parent activity, but it's better to keep it within the fragment if possible, so that you could have multiple fragments without id conflicts. (For example; I know two login forms isn't a likely scenario.)

So the first thing I would do is move both loginClick and loadPreferences into PlaceholderFragment. (You can rename PlaceholderFragment into something more useful too, of course.) Once it's moved, you'll call loadPreferences in onCreateView instead of Activity.onCreate. This should make more sense to you - loadPreferences is populating the view, so it should happen as the view is being created.

However, getView() still won't work here. Instead, you have to use the rootView that's being created in the process of onCreateView. This is because getView only finds out what the root view is after it's returned from onCreateView. Therefore, a good way to solve the problem would be to simply pass rootView into loadPreferences, and use rootView.findViewById.