Aktivität ActionBar ist in Fragment nicht sichtbar

Question

Ich habe ein Problem mit ActionBar in meinem Fragment. Es ist darin unsichtbar, so dass ich getActionBar().setDisplayHomeAsUpEnabled(true); in meinem SignUpActivity.java nicht ausführen kann. In jeder anderen Aktivität (nicht Fragment) ist es sichtbar.

Können Sie mir sagen, was ich falsch mache? Vermutlich fehlt etwas.

fragment_sign_up.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_width="match_parent" 
android:layout_height="fill_parent" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_marginLeft="10dp" 
android:layout_marginRight="10dp" 
tools:context="com.msh.organizer.SignUpActivity"> 

<EditText 
    android:layout_below="@id/toolbar" 
android:id="@+id/nickname_et" 
    android:hint="@string/nickname" 
    android:layout_marginTop="40dp" 
android:layout_width="match_parent" 
android:layout_height="wrap_content" /> 

<EditText 
    android:id="@+id/email_et" 
    android:hint="@string/mail" 
    android:layout_marginTop="5dp" 
    android:layout_below="@id/nickname_et" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" /> 

<EditText 
    android:id="@+id/password_et" 
    android:hint="@string/password" 
    android:inputType="textPassword" 
    android:layout_marginTop="5dp" 
    android:layout_below="@id/email_et" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" /> 

<Button 
    android:id="@+id/sign_up_btn" 
    android:layout_marginTop="15dp" 
    android:layout_below="@id/password_et" 
    android:text="@string/sign_up" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" /> 

activity_sign_up.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:id="@+id/container" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
tools:context="com.msh.organizer.SignUpActivity" 
tools:ignore="MergeRootFrame" /> 

SignUpActivity.java

package com.msh.organizer; 

import android.app.Activity; 
import android.os.Bundle; 
import android.support.v7.app.AppCompatActivity; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.widget.Toast; 

public class SignUpActivity extends Activity { 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_sign_up); 

    //getActionBar().setDisplayHomeAsUpEnabled(true); 

    if (savedInstanceState == null) { 
     getFragmentManager().beginTransaction() 
       .add(R.id.container, new SignUpFragment()) 
       .commit(); 
    } 
    //Toast.makeText(this,"Sign Up", Toast.LENGTH_LONG).show(); 
} 


@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); 
} 
} 

SignUpFragment.java

package com.msh.organizer; 

import android.app.Activity; 
import android.app.Fragment; 
import android.os.Bundle; 
import android.support.v7.app.AppCompatActivity; 
import android.text.TextUtils; 
import android.util.Patterns; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.Toast; 

import com.parse.ParseException; 
import com.parse.ParseUser; 
import com.parse.SignUpCallback; 


public class SignUpFragment extends Fragment implements View.OnClickListener { 
private Button mSignUpButton; 
private EditText mNickNameEditText; 
private EditText mEmailEditText; 
private EditText mPasswordEditText; 

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

    mSignUpButton = (Button) rootView.findViewById(R.id.sign_up_btn); 
    mNickNameEditText = (EditText) rootView.findViewById(R.id.nickname_et); 
    mEmailEditText = (EditText) rootView.findViewById(R.id.email_et); 
    mPasswordEditText = (EditText) rootView.findViewById(R.id.password_et); 

    return rootView; 
} 

@Override 
public void onViewCreated(View view, Bundle savedInstanceState) { 
    super.onViewCreated(view, savedInstanceState); 
    mSignUpButton.setOnClickListener(this); 
} 

@Override 
public void onClick(View v) { 
    switch (v.getId()) { 
     case R.id.sign_up_btn: 
      trySignUp(); 
      break; 
    } 
} 

private void trySignUp() { 
    String nickname = mNickNameEditText.getText().toString(); 
    String email = mEmailEditText.getText().toString(); 
    String password = mPasswordEditText.getText().toString(); 
    boolean failed = false; 

    if (TextUtils.isEmpty(nickname)){ 
     mNickNameEditText.setError("Nickname cannnot be empty!"); 
     failed = true; 
    } 

    if (TextUtils.isEmpty(password)){ 
     mPasswordEditText.setError("Password cannnot be empty!"); 
     failed = true; 
    } 

    if (TextUtils.isEmpty(email)){ 
     mEmailEditText.setError("Email cannnot be empty!"); 
     failed = true; 
    } 

    if (!Patterns.EMAIL_ADDRESS.matcher(email).matches()){ 
     mEmailEditText.setError("Inwalid E-mail address!"); 
     failed = true; 
    } 
    if (!failed){ 
     signUp(nickname, email, password); 
    } 

} 

private void signUp(String nickname, String email, String password) { 
    ParseUser user = new ParseUser(); 
    user.setUsername(email); 
    user.setPassword(password); 
    user.setEmail(email); 

// other fields can be set just like with ParseObject 
    user.put("nickname", nickname); 

    user.signUpInBackground(new SignUpCallback() { 
     public void done(ParseException e) { 
      if (e == null) { 
       if (getActivity() != null){ 
        getActivity().setResult(Activity.RESULT_OK); 
        getActivity().finish(); 
       } 
      } else { 
       if (getActivity() != null) { 
        Toast.makeText(getActivity(), e.getLocalizedMessage(),  Toast.LENGTH_LONG).show(); 
       } 
      } 
     } 
    }); 
} 
} 

Answer 1

können Sie Toolbar innerhalb eines AppBarLayout in Ihrer Tätigkeit nutzen:

SignUpActivity.java

... 

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
    setSupportActionBar(toolbar); 

    final ActionBar ab = getSupportActionBar(); 
    ab.setHomeAsUpIndicator(R.drawable.ic_menu); 
    ab.setDisplayHomeAsUpEnabled(true); 

    ... 

activity_sign_up.xml

<android.support.design.widget.AppBarLayout 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:id="@+id/appbar" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"> 

    <android.support.v7.widget.Toolbar 
     android:id="@+id/toolbar" 
     android:layout_width="match_parent" 
     android:layout_height="?attr/actionBarSize" 
     android:background="?attr/colorPrimary" 
     app:popupTheme="@style/ThemeOverlay.AppCompat.Light" 
     app:layout_scrollFlags="scroll|enterAlways|snap" /> 

</android.support.design.widget.AppBarLayout> 

<FrameLayout 
    android:id="@+id/container" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    tools:context="com.msh.organizer.SignUpActivity" 
    tools:ignore="MergeRootFrame" />