Android.support.v7.widget.TintContextWrapper无法投射

Question

我正在制作一个任务提醒应用程序，遵循一些教程。它有两个活动，即TaskListActivity和TaskEditActivity。 TaskList活动运行良好，但是当我尝试使用意图导航到TaskEditActivity时，它崩溃。 下面是我的清单文件：

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

<uses-permission android:name="android.permission.INTERNET" /> 

<application 
    android:allowBackup="true" 
    android:icon="@mipmap/ic_launcher" 
    android:label="@string/app_name" 
    android:supportsRtl="true" 
    android:theme="@style/AppTheme"> 
    <activity 
     android:name=".TaskListActivity" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme.NoActionBar"> 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 

      <category android:name="android.intent.category.LAUNCHER" /> 
     </intent-filter> 
    </activity> 
    <activity 
     android:name=".TaskEditActivity" 
     android:label="@string/title_activity_task_edit" 
     android:parentActivityName=".TaskListActivity" 
     android:theme="@style/AppTheme.NoActionBar"> 
     <meta-data 
      android:name="android.support.PARENT_ACTIVITY" 
      android:value="com.dummies.tasks.activity.TaskListActivity" /> 
    </activity> 
</application> 

而下面是我的build.gradle文件：

apply plugin: 'com.android.application' 

android { 
    compileSdkVersion 24 
    buildToolsVersion "24.0.0" 

    defaultConfig { 
     applicationId "com.dummies.tasks" 
     minSdkVersion 21 
     targetSdkVersion 24 
     versionCode 1 
     versionName "1.0" 
    } 
    buildTypes { 
     release { 
      minifyEnabled false 
      proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' 
     } 
    } 
} 

dependencies { 
    compile fileTree(dir: 'libs', include: ['*.jar']) 

    testCompile 'junit:junit:4.12' 

    compile 'com.android.support:appcompat-v7:24.1.1' 
    compile 'com.android.support:design:24.1.1' 
    compile 'com.android.support:support-v4:24.1.1' 
    compile 'com.android.support:recyclerview-v7:24.1.1' 
    compile 'com.android.support:cardview-v7:24.1.1' 

    compile 'com.squareup.picasso:picasso:2.4.0' 

} 

它的logcat如下：

FATAL EXCEPTION: main 
                    Process: com.dummies.tasks, PID: 10754 
                    **java.lang.ClassCastException: android.support.v7.widget.TintContextWrapper cannot be cast to com.dummies.tasks.interfaces.OnEditTask** 
                     at **com.dummies.tasks.adapter.TaskListAdapter$1.onClick(TaskListAdapter.java:51) 
                     at android.view.View.performClick(View.java:4791)** 
                     at android.view.View$PerformClick.run(View.java:19884) 
                     at android.os.Handler.handleCallback(Handler.java:739) 
                     at android.os.Handler.dispatchMessage(Handler.java:95) 
                     at android.os.Looper.loop(Looper.java:135) 
                     at android.app.ActivityThread.main(ActivityThread.java:5268) 
                     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:902) 
                     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697) 
08-07 15:16:46.625 10754-10754/com.dummies.tasks I/Process: Sending signal. PID: 10754 SIG: 9 

适配器类：

package com.dummies.tasks.adapter; 
import android.content.Context; 
import android.support.v7.widget.CardView; 
import android.support.v7.widget.RecyclerView; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.ImageView; 
import android.widget.TextView; 

import com.dummies.tasks.activity.R; 
import com.dummies.tasks.interfaces.OnEditTask; 
import com.squareup.picasso.Picasso; 

/** 
* Created by panwa on 8/7/2016. 
*/ 
public class TaskListAdapter 
     extends RecyclerView.Adapter<TaskListAdapter.ViewHolder> 
     { 
static String[] fakeData = new String[] { 
     "One", 
     "Two", 
     "Three", 
     "Four", 
     "Five", 
     "Ah . . . ah . . . ah!" 
     }; 
@Override 
public ViewHolder onCreateViewHolder(ViewGroup parent, int i) { 
// create a new view 
     CardView v = (CardView) LayoutInflater.from(parent.getContext()) 
     .inflate(R.layout.card_task, parent, false); 
// wrap it in a ViewHolder 
     return new ViewHolder(v); 
     } 
@Override 
public void onBindViewHolder(ViewHolder viewHolder, final int i) { 
    final Context context = viewHolder.titleView.getContext(); 
    viewHolder.titleView.setText(fakeData[i]); 
// set the thumbnail image 
    Picasso.with(context) 
      .load(getImageUrlForTask(i)) 
      .into(viewHolder.imageView); 
// Set the click action 
    viewHolder.cardView.setOnClickListener(
      new View.OnClickListener() { 
       @Override 
       public void onClick(View view) { 
        ((OnEditTask) context).editTask(i); 
       } 
      }); 
} 
@Override 
public int getItemCount() { 
     return fakeData.length; 
     } 
      public static String getImageUrlForTask(long taskId) { 
       return "http://lorempixel.com/600/400/cats/?fakeId=" + taskId; 
      } 
static class ViewHolder extends RecyclerView.ViewHolder { 
    CardView cardView; 
    TextView titleView; 
    ImageView imageView; 
    public ViewHolder(CardView card) { 
     super(card); 
     cardView = card; 
     titleView = (TextView)card.findViewById(R.id.text1); 
     imageView = (ImageView)card.findViewById(R.id.image); 
    } 
} 
} 

TaskEditActivity活动，我想从TaskListActivity导航：

package com.dummies.tasks.activity; 

    import android.os.Bundle; 
    import android.support.design.widget.FloatingActionButton; 
    import android.support.design.widget.Snackbar; 
    import android.support.v7.app.AppCompatActivity; 
    import android.support.v7.widget.Toolbar; 
    import android.view.View; 



    public class TaskEditActivity extends AppCompatActivity { 
     public static final String EXTRA_TASKID = "taskId"; 

     @Override 
     protected void onCreate(Bundle savedInstanceState) { 
      super.onCreate(savedInstanceState); 
      setContentView(R.layout.activity_task_edit); 
      Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
      setSupportActionBar(toolbar); 
      getSupportActionBar().setDisplayHomeAsUpEnabled(true); 
     } 

    } 

TaskListActivity或主要活动：

package com.dummies.tasks.activity; 

import android.content.Intent; 
import android.os.Bundle; 
import android.support.design.widget.FloatingActionButton; 
import android.support.design.widget.Snackbar; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.view.View; 
import android.view.Menu; 
import android.view.MenuItem; 

import com.dummies.tasks.interfaces.OnEditTask; 

public class TaskListActivity extends AppCompatActivity implements OnEditTask { 

    @Override 


    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_task_list); 
     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 




    } 
    @Override 
    public void editTask(long id) { 
// When we are asked to edit a reminder, start the 
// TaskEditActivity with the id of the task to edit. 
     startActivity(new Intent(this, TaskEditActivity.class) 
       .putExtra(TaskEditActivity.EXTRA_TASKID, id)); 
    } 
} 

OnEditTask接口：

package com.dummies.tasks.interfaces; 
public interface OnEditTask { 
    /** 
    * Called when the user asks to edit or insert a task. 
    */ 
    public void editTask(long id); 
} 

Answer 1

您的活动延伸至AppCompatActivity。由于支持库版本23.3.0 View.getContext()返回TintContextWrapper对象而不是Activity。您可以按照此处所述提取Activity：https://stackoverflow.com/a/32973351/6009935