Fehler beim Aufblasen der Klasse Fragment beim Testen des Fragments mit DataBinding

Question

Kann mir jemand dabei helfen? In meinem Test möchte ich überprüfen, ob die Login-Schaltfläche auf der Startseite angezeigt wird. Ich habe heute eine Weile mit diesem Fehler gekämpft und weiß nicht, wie es gelöst werden sollte. Was fehlt mir hier?

Vielleicht ist das Problem auf diese Frage irgendwie ähnlich: Espresso test fails with java.lang.String cannot be cast to com.abc.events.databinding.SponsorDetailBinding

android.view.InflateException: Binary XML file line #6: Error inflating class fragment 
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:770) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:483) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:415) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:366) 
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:256) 
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109) 
at io.turbela.turbela.login.view.StartActivity.onCreate(StartActivity.java:16) 
at android.app.Activity.performCreate(Activity.java:6289) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119) 
at android.support.test.runner.MonitoringInstrumentation.callActivityOnCreate(MonitoringInstrumentation.java:532) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2655) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2767) 
at android.app.ActivityThread.access$900(ActivityThread.java:177) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1449) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:145) 
at android.app.ActivityThread.main(ActivityThread.java:5951) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1400) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1195) 
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void io.turbela.turbela.databinding.FragmentStartBinding.setViewModel(io.turbela.turbela.login.viewmodel.DispatchViewModel)' on a null object reference 
at io.turbela.turbela.StartActivityFragment.onCreateView(StartActivityFragment.java:34) 
at android.app.Fragment.performCreateView(Fragment.java:2114) 
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:875) 
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1060) 
at android.app.FragmentManagerImpl.addFragment(FragmentManager.java:1162) 
at android.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2131) 
at android.app.Activity.onCreateView(Activity.java:5610) 
at android.support.v4.app.BaseFragmentActivityHoneycomb.onCreateView(BaseFragmentActivityHoneycomb.java:34) 
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:79) 
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:740) 
... 20 more 

LoginTest.java

@RunWith(AndroidJUnit4.class) 
public class LoginTest { 

@Rule 
public ActivityTestRule<StartActivity> mActivityRule = new ActivityTestRule(StartActivity.class); 

@Test 
public void displayLoginPage() { 
    onView(withId(R.id.login_button)).check(matches(isDisplayed())); 
} 
} 

StartActivity.java

public class StartActivity extends AppCompatActivity { 

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

activity_start.xml

<fragment xmlns:android="http://schemas.android.com/apk/res/android" 
android:id="@+id/fragment" 
class="io.turbela.turbela.StartActivityFragment" 
android:layout_width="match_parent" 
android:layout_height="match_parent"/> 

StartActivityFragment.java

public class StartActivityFragment extends Fragment { 

public StartActivityFragment() { 
} 

public static StartActivityFragment newInstance(){ 
    Bundle args = new Bundle(); 
    args.putString("key", "value"); 
    StartActivityFragment fragment = new StartActivityFragment(); 
    fragment.setArguments(args); 
    return fragment; 
} 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    FragmentStartBinding binding = DataBindingUtil.inflate(inflater, R.layout.fragment_start, container, false); 
    binding.setViewModel(new DispatchViewModel()); 
    return binding.getRoot(); 
} 
} 

fragment_start.xml

<layout xmlns:android="http://schemas.android.com/apk/res/android"> 

<data> 
    <variable name="viewModel" type="io.turbela.turbela.login.viewmodel.DispatchViewModel" /> 
</data> 

<RelativeLayout 
    style="@android:style/Theme.Holo" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:paddingBottom="@dimen/activity_vertical_margin" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin"> 

    <Button 
     android:id="@+id/login_button" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentRight="true" 
     android:layout_alignParentStart="true" 
     android:layout_alignParentEnd="true" 
     android:layout_alignParentTop="true" 
     android:layout_marginTop="128dp" 
     android:onClick="@{viewModel.onClickLogin}" 
     android:text="@string/login" /> 
</RelativeLayout> 
</layout> 

DispatchViewModel.java

public class DispatchViewModel extends BaseObservable{ 


public View.OnClickListener onClickLogin() { 
    //loginWithEmail 
    return v -> Log.d("H", "onClickLogin"); 
} 
} 

build.gradle

apply plugin: 'com.android.application' 
apply plugin: 'me.tatarka.retrolambda' 

android { 
compileSdkVersion 23 
buildToolsVersion "22.0.1" 

defaultConfig { 
    applicationId "io.turbela.turbela" 
    minSdkVersion 15 
    targetSdkVersion 23 
    versionCode 1 
    versionName "1.0" 
    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" 
} 

dataBinding{ 
    enabled = true 
} 

packagingOptions { 
    exclude 'LICENSE.txt' 
} 
lintOptions { 
    abortOnError false 
} 

compileOptions { 
    sourceCompatibility JavaVersion.VERSION_1_8 
    targetCompatibility JavaVersion.VERSION_1_8 
} 
buildTypes { 
    release { 
     minifyEnabled false 
     proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' 
    } 
} 
} 

dependencies { 
compile fileTree(dir: 'libs', include: ['*.jar']) 
compile 'com.android.support:cardview-v7:23.1.1' 
compile 'com.android.support:appcompat-v7:23.1.1' 
compile 'com.parse:parse-android:1.12.0' 
compile 'com.parse.bolts:bolts-android:1.3.0' 
compile 'com.facebook.android:facebook-android-sdk:4.8.1' 
compile 'com.parse:parsefacebookutils-v4-android:1.10.3@aar' 


androidTestCompile 'com.android.support.test.espresso:espresso-core:2.2.2' 
androidTestCompile 'com.android.support.test:runner:0.5' 

} 

Answer 1

Es gibt android:name Attribut von <fragment> Tag in Ihrem fehlenden activity_start.xml

Gemäß den docs, müssen Sie es schließen.

So Ihre activity.start.xml sollte wie folgt aussehen:

<fragment xmlns:android="http://schemas.android.com/apk/res/android" 
android:id="@+id/fragment" 
android:name="io.turbela.turbela.StartActivityFragment" 
android:layout_width="match_parent" 
android:layout_height="match_parent"/> 

Hinweis:

Die class= Attribut, das Sie versuchen, wie in here