Question

我的应用程序在启动时出现以下错误而崩溃。

05-13 05:55:33.031: E/AndroidRuntime(1022): FATAL EXCEPTION: main
05-13 05:55:33.031: E/AndroidRuntime(1022): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.myphonecall/com.example.myphonecall.MyPhoneCall}: java.lang.ClassCastException: com.example.myphonecall.MyPhoneCall cannot be cast to android.app.Activity
05-13 05:55:33.031: E/AndroidRuntime(1022):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2106)
05-13 05:55:33.031: E/AndroidRuntime(1022):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
05-13 05:55:33.031: E/AndroidRuntime(1022):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
05-13 05:55:33.031: E/AndroidRuntime(1022):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
05-13 05:55:33.031: E/AndroidRuntime(1022):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-13 05:55:33.031: E/AndroidRuntime(1022):     at android.os.Looper.loop(Looper.java:137)
05-13 05:55:33.031: E/AndroidRuntime(1022):     at android.app.ActivityThread.main(ActivityThread.java:5039)
05-13 05:55:33.031: E/AndroidRuntime(1022):     at java.lang.reflect.Method.invokeNative(Native Method)
05-13 05:55:33.031: E/AndroidRuntime(1022):     at java.lang.reflect.Method.invoke(Method.java:511)
05-13 05:55:33.031: E/AndroidRuntime(1022):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
05-13 05:55:33.031: E/AndroidRuntime(1022):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
05-13 05:55:33.031: E/AndroidRuntime(1022):     at dalvik.system.NativeStart.main(Native Method)
05-13 05:55:33.031: E/AndroidRuntime(1022): Caused by: java.lang.ClassCastException: com.example.myphonecall.MyPhoneCall cannot be cast to android.app.Activity
05-13 05:55:33.031: E/AndroidRuntime(1022):     at android.app.Instrumentation.newActivity(Instrumentation.java:1054)
05-13 05:55:33.031: E/AndroidRuntime(1022):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2097)
05-13 05:55:33.031: E/AndroidRuntime(1022):     ... 11 more

CODE

MyPhoneCall.java package com.example.myphonecall;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.telephony.TelephonyManager;
import android.util.Log;
import android.widget.Toast;

public class MyPhoneCall extends BroadcastReceiver {

  @Override
  public void onReceive(Context context, Intent intent) {
    Bundle extras = intent.getExtras();
    if (extras != null) {
      String state = extras.getString(TelephonyManager.EXTRA_STATE);
      Log.w("MY_DEBUG_TAG", state);
      if (state.equals(TelephonyManager.EXTRA_STATE_RINGING)) {
    String phoneNumber = extras
        .getString(TelephonyManager.EXTRA_INCOMING_NUMBER);
    //Log.w("MY_DEBUG_TAG", phoneNumber);
    Toast.makeText(context, "Getting Call from "+phoneNumber, Toast.LENGTH_LONG).show();
      }
    }
  }
}

的AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myphonecall"
    android:versionCode="1"
    android:versionName="1.0" >

     <uses-sdk android:minSdkVersion="15" />

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

    <application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name" >
       <activity
        android:name=".MyPhoneCall"
        android:label="MyPhoneCall" >
        <intent-filter>
        <action android:name="android.intent.action.MAIN" />

        <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <receiver android:name="MyPhoneReceiver" >
        <intent-filter>
        <action android:name="android.intent.action.PHONE_STATE" >
        </action>
        </intent-filter>
    </receiver>
    </application>



</manifest>

Answer 1

您的MyPhoneCall是BroadcastReceiver并且您将其声明为activity。所以它给你错误。

05-13 05:55:33.031: E/AndroidRuntime(1022): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.myphonecall/com.example.myphonecall.MyPhoneCall}: java.lang.ClassCastException: com.example.myphonecall.MyPhoneCall cannot be cast to android.app.Activity

按以下方式声明。

<receiver android:name=".MyPhoneCall" >
        <intent-filter>
            <action ...... />
            <action ..... />
        </intent-filter>
    </receiver>

Answer 2

MyPhoneCall.java 是BroadcastReceiver。它不是Activity。但是在AndroidManifest.xml中，您已将其声明为Activity。因此，您会收到ClassCastException。

Answer 3

某处您尝试将该类作为活动启动。它不是 - 它的接收器。活动是具有UI的工作流，该UI可以接收用户输入并保持电话的前景。 BroadcastReceiver是一段短暂的代码，它响应事件然后消失。它没有UI，不与用户交互，并且快速退出。基于这个和前一个问题，我认为你不理解它们。

Answer 4

在Manifest中，您已将MyPhoneCall声明为活动。但是在代码中，您已经使用广播接收器扩展了MyPhoneCall类。

Answer 5

因为My Phone Call类没有扩展Activity类，这就是为什么会出现这个错误。不要放入活动块。只需在清单

中的Receiver块中注册即可

应用程序不会使用FATAL EXCEPTION启动

5 个答案: