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Невозможно использовать двустороннюю привязку данных с ObservableField <String>

2016-10-25 12 views
1

Это мой макетНевозможно использовать двустороннюю привязку данных с ObservableField <String>

<?xml version="1.0" encoding="utf-8"?> 


<data> 

    <import type="android.view.View" /> 

    <import type="android.databinding.ObservableField"/> 

    <variable 
     name="message" 
     type="ObservableField&lt;String&gt;"/> 


</data> 


<LinearLayout 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:orientation="vertical"> 


    <android.support.v7.widget.Toolbar 
     android:id="@+id/toolbar" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:theme="@style/ToolbarTheme" 
     app:elevation="4dp" /> 


    <RelativeLayout 
     android:layout_width="match_parent" 
     android:layout_height="match_parent"> 


     <RelativeLayout 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:layout_alignParentBottom="true"> 


      <RelativeLayout 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_centerVertical="true" 
       android:layout_marginBottom="@dimen/activity_vertical_margin" 
       android:layout_marginEnd="8dp" 
       android:layout_marginLeft="8dp" 
       android:layout_marginRight="8dp" 
       android:layout_marginStart="8dp" 
       android:layout_toLeftOf="@+id/send" 
       android:layout_toStartOf="@+id/send" 
       android:background="@drawable/balloon_outgoing_normal" 
       android:padding="4dp"> 


       <android.support.v7.widget.AppCompatEditText 
        android:layout_width="match_parent" 
        android:layout_height="wrap_content" 
        android:layout_centerVertical="true" 
        android:text="@={message.get()}" 
        android:layout_marginLeft="8dp" 
        android:layout_marginStart="8dp" 
        android:layout_toLeftOf="@+id/audio" 
        android:layout_toStartOf="@+id/audio" /> 


       <android.support.v7.widget.AppCompatImageView 
        android:id="@+id/audio" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:layout_centerVertical="true" 
        android:layout_toLeftOf="@+id/camera" 
        android:layout_toStartOf="@id/camera" 
        android:background="?attr/selectableItemBackground" 
        android:padding="8dp" 
        android:src="@drawable/ic_mic_white_24dp" 
        android:tint="@color/iconDefault" 
        android:visibility="@{message.get().length()==0?View.VISIBLE:View.GONE}" /> 


       <android.support.v7.widget.AppCompatImageView 
        android:id="@+id/camera" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:layout_alignParentEnd="true" 
        android:layout_alignParentRight="true" 
        android:layout_centerVertical="true" 
        android:layout_marginEnd="8dp" 
        android:layout_marginRight="8dp" 
        android:background="?attr/selectableItemBackground" 
        android:padding="8dp" 
        android:src="@drawable/ic_photo_camera_black_24dp" 
        android:tint="@color/iconDefault" 
        android:visibility="@{message.get().length()==0?View.VISIBLE:View.GONE}" /> 


      </RelativeLayout> 


      <android.support.design.widget.FloatingActionButton 
       android:id="@+id/send" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:layout_alignParentEnd="true" 
       android:layout_alignParentRight="true" 
       android:layout_centerVertical="true" 
       android:layout_marginBottom="@dimen/activity_vertical_margin" 
       android:layout_marginEnd="8dp" 
       android:layout_marginRight="8dp" 
       android:src="@drawable/ic_send_white_24dp" 
       app:elevation="6dp" 
       app:fabSize="normal" /> 


     </RelativeLayout> 


    </RelativeLayout> 


</LinearLayout> 
</layout>

Где двухсторонняя часть:

<android.support.v7.widget.AppCompatEditText 
        android:layout_width="match_parent" 
        android:layout_height="wrap_content" 
        android:layout_centerVertical="true" 
        android:text="@={message.get()}" 
        android:layout_marginLeft="8dp" 
        android:layout_marginStart="8dp" 
        android:layout_toLeftOf="@+id/audio" 
        android:layout_toStartOf="@+id/audio" />

и это stacktrace:

* What went wrong: 
Execution failed for task ':app:compileDebugJavaWithJavac'. 
> java.lang.RuntimeException: failure, see logs for details. 
    cannot generate view binders java.lang.NullPointerException 
    at android.databinding.tool.expr.MethodCallExpr.generateCode(MethodCallExpr.java:72) 
    at android.databinding.tool.expr.Expr.toFullCode(Expr.java:745) 
    at android.databinding.tool.expr.Expr.assertIsInvertible(Expr.java:767) 
    at android.databinding.tool.BindingTarget.addInverseBinding(BindingTarget.java:68) 
    at android.databinding.tool.LayoutBinder.(LayoutBinder.java:229) 
    at android.databinding.tool.DataBinder.(DataBinder.java:52) 
    at android.databinding.tool.CompilerChef.ensureDataBinder(CompilerChef.java:86) 
    at android.databinding.tool.CompilerChef.sealModels(CompilerChef.java:200) 
    at android.databinding.annotationprocessor.ProcessExpressions.writeResourceBundle(ProcessExpressions.java:149) 
    at android.databinding.annotationprocessor.ProcessExpressions.onHandleStep(ProcessExpressions.java:82) 
    at android.databinding.annotationprocessor.ProcessDataBinding$ProcessingStep.runStep(ProcessDataBinding.java:154) 
    at android.databinding.annotationprocessor.ProcessDataBinding$ProcessingStep.access$000(ProcessDataBinding.java:139) 
    at android.databinding.annotationprocessor.ProcessDataBinding.process(ProcessDataBinding.java:66) 
    at com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcessor(JavacProcessingEnvironment.java:794) 
    at com.sun.tools.javac.processing.JavacProcessingEnvironment.discoverAndRunProcs(JavacProcessingEnvironment.java:705) 
    at com.sun.tools.javac.processing.JavacProcessingEnvironment.access$1800(JavacProcessingEnvironment.java:91) 
    at com.sun.tools.javac.processing.JavacProcessingEnvironment$Round.run(JavacProcessingEnvironment.java:1035) 
    at com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:1176) 
    at com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:1170) 
    at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:856) 
    at com.sun.tools.javac.main.Main.compile(Main.java:523) 
    at com.sun.tools.javac.api.JavacTaskImpl.doCall(JavacTaskImpl.java:129) 
    at com.sun.tools.javac.api.JavacTaskImpl.call(JavacTaskImpl.java:138) 
    at org.gradle.api.internal.tasks.compile.JdkJavaCompiler.execute(JdkJavaCompiler.java:46) 
    at org.gradle.api.internal.tasks.compile.JdkJavaCompiler.execute(JdkJavaCompiler.java:33) 
    at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.delegateAndHandleErrors(NormalizingJavaCompiler.java:104) 
    at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.execute(NormalizingJavaCompiler.java:53) 
    at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.execute(NormalizingJavaCompiler.java:38) 
    at org.gradle.api.internal.tasks.compile.CleaningJavaCompilerSupport.execute(CleaningJavaCompilerSupport.java:35) 
    at org.gradle.api.internal.tasks.compile.CleaningJavaCompilerSupport.execute(CleaningJavaCompilerSupport.java:25) 
    at org.gradle.api.tasks.compile.JavaCompile.performCompilation(JavaCompile.java:163) 
    at org.gradle.api.tasks.compile.JavaCompile.compile(JavaCompile.java:145) 
    at org.gradle.api.tasks.compile.JavaCompile.compile(JavaCompile.java:93) 
    at com.android.build.gradle.tasks.factory.AndroidJavaCompile.compile(AndroidJavaCompile.java:49) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:498) 
    at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:75) 
    at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$IncrementalTaskAction.doExecute(AnnotationProcessingTaskFactory.java:245) 
    at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:221) 
    at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$IncrementalTaskAction.execute(AnnotationProcessingTaskFactory.java:232) 
    at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:210) 
    at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:80) 
    at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:61) 
    at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:46) 
    at org.gradle.api.internal.tasks.execution.PostExecutionAnalysisTaskExecuter.execute(PostExecutionAnalysisTaskExecuter.java:35) 
    at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:66) 
    at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:58) 
    at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:52) 
    at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:52) 
    at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:53) 
    at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:43) 
    at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:203) 
    at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:185) 
    at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.processTask(AbstractTaskPlanExecutor.java:66) 
    at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.run(AbstractTaskPlanExecutor.java:50) 
    at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor.process(DefaultTaskPlanExecutor.java:25) 
    at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter.execute(DefaultTaskGraphExecuter.java:110) 
    at org.gradle.execution.SelectedTaskExecutionAction.execute(SelectedTaskExecutionAction.java:37) 
    at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:37) 
    at org.gradle.execution.DefaultBuildExecuter.access$000(DefaultBuildExecuter.java:23) 
    at org.gradle.execution.DefaultBuildExecuter$1.proceed(DefaultBuildExecuter.java:43) 
    at org.gradle.execution.DryRunBuildExecutionAction.execute(DryRunBuildExecutionAction.java:32) 
    at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:37) 
    at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:30) 
    at org.gradle.initialization.DefaultGradleLauncher$4.run(DefaultGradleLauncher.java:153) 
    at org.gradle.internal.Factories$1.create(Factories.java:22) 
    at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:91) 
    at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:53) 
    at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:150) 
    at org.gradle.initialization.DefaultGradleLauncher.access$200(DefaultGradleLauncher.java:32) 
    at org.gradle.initialization.DefaultGradleLauncher$1.create(DefaultGradleLauncher.java:98) 
    at org.gradle.initialization.DefaultGradleLauncher$1.create(DefaultGradleLauncher.java:92) 
    at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:91) 
    at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:63) 
    at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:92) 
    at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:83) 
    at org.gradle.launcher.exec.InProcessBuildActionExecuter$DefaultBuildController.run(InProcessBuildActionExecuter.java:99) 
    at org.gradle.tooling.internal.provider.runner.BuildModelActionRunner.run(BuildModelActionRunner.java:46) 
    at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35) 
    at org.gradle.tooling.internal.provider.runner.SubscribableBuildActionRunner.run(SubscribableBuildActionRunner.java:58) 
    at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35) 
    at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:48) 
    at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:30) 
    at org.gradle.launcher.exec.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:81) 
    at org.gradle.launcher.exec.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:46) 
    at org.gradle.launcher.daemon.server.exec.ExecuteBuild.doBuild(ExecuteBuild.java:52) 
    at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36) 
    at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120) 
    at org.gradle.launcher.daemon.server.exec.WatchForDisconnection.execute(WatchForDisconnection.java:37) 
    at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120) 
    at org.gradle.launcher.daemon.server.exec.ResetDeprecationLogger.execute(ResetDeprecationLogger.java:26) 
    at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120) 
    at org.gradle.launcher.daemon.server.exec.RequestStopIfSingleUsedDaemon.execute(RequestStopIfSingleUsedDaemon.java:34) 
    at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120) 
    at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.call(ForwardClientInput.java:74) 
    at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.call(ForwardClientInput.java:72) 
    at org.gradle.util.Swapper.swap(Swapper.java:38) 
    at org.gradle.launcher.daemon.server.exec.ForwardClientInput.execute(ForwardClientInput.java:72) 
    at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120) 
    at org.gradle.launcher.daemon.server.health.DaemonHealthTracker.execute(DaemonHealthTracker.java:47) 
    at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120) 
    at org.gradle.launcher.daemon.server.exec.LogToClient.doBuild(LogToClient.java:60) 
    at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36) 
    at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120) 
    at org.gradle.launcher.daemon.server.exec.EstablishBuildEnvironment.doBuild(EstablishBuildEnvironment.java:72) 
    at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36) 
    at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120) 
    at org.gradle.launcher.daemon.server.health.HintGCAfterBuild.execute(HintGCAfterBuild.java:41) 
    at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120) 
    at org.gradle.launcher.daemon.server.exec.StartBuildOrRespondWithBusy$1.run(StartBuildOrRespondWithBusy.java:50) 
    at org.gradle.launcher.daemon.server.DaemonStateCoordinator$1.run(DaemonStateCoordinator.java:237) 
    at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:54) 
    at org.gradle.internal.concurrent.StoppableExecutorImpl$1.run(StoppableExecutorImpl.java:40) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) 
    at java.lang.Thread.run(Thread.java:745)

Если я не использую двустороннюю привязку данных, заменяющую android:text="@={message.get()}" с android:text="@{message.get()}", все работает нормально. Итак, каков правильный путь?

источник

2016-10-25 Bronx

+0

У вас есть сеттер для вашего «сообщения»? – yennsarah

+0

@Amylinn «message» - это ObservableField , он должен быть обработан как ObservableBoolean, ObservableInt ... (который работает с двухсторонней привязкой данных) – Bronx

ответ

1

Вы используете ObservableField - который работает немного иначе, чем встроенный ObservableBoolean или ObservableInt.

С message.get() вы только получать String хранится в ObservableField, то DataBinding не знает, как сохранить введенные данные в нем. После example Джорджа горы (разработчик библиотеки DataBinding), вы должны сделать следующее:

  1. Создать в своем классе в public final ObservableField<String>. Класс может быть простым классом Java, вашей деятельностью или фрагментом, в котором вы находитесь.

  2. Передайте ссылку на класс на ваш xml.

  3. Использование android:text="@{myClass.myField}"

Полный пример:

public class MainActivity extends AppCompatActivity { 
    public final ObservableField<String> message = new ObservableField<>(); 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     DataBindingUtil.setContentView(this, R.layout.activity_main); 
     message.set("Hello"); //initial data 
    } 
}

И activity_main.xml:

<?xml version="1.0" encoding="utf-8"?> 
<layout> 
    <data> 
     <variable 
      name="myClass" 
      type="com.example.yourpackage.test.MainActivity"/> 
    </data> 

    <RelativeLayout  
     xmlns:android="http://schemas.android.com/apk/res/android" 
     xmlns:tools="http://schemas.android.com/tools"   
     android:layout_width="match_parent" 
     android:layout_height="match_parent"> 

     <android.support.v7.widget.AppCompatEditText 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:text="@={myClass.message}" /> 
    </RelativeLayout> 
</layout>

Вы также можете обернуть Fields с дополнительным классом, чтобы сохранить ваш MainActivity чистый ,

источник

2016-10-27 09:32:08 yennsarah

+0

Моя ошибка заключалась в том, что ObservableFields и ObservableBoolean работают одинаково, к сожалению, единственный способ чтобы сделать его работу за вами (добавив активность как переменную) – Bronx

+0

Я попробовал это сам, прежде чем писать это;) Обычно я использую своего рода шаблон MVVM, где храню необходимые переменные в моей «ViewModel», которая работает достаточно хорошо. – yennsarah

+0

спасибо за предложение :) – Bronx

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