1

我正在尝试取消注册清单文件上的接收器使用。我使用链接中给出的方法，但是当我尝试启动 ComponentName 对象时它给了我一个空指针异常

这是代码

主班

public class MainActivity extends Activity {
    Button StopB;
    //Context context;

错误在下面的行中，

ComponentName component =new ComponentName(getApplicationContext(), BRR.class);
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        StopB=(Button) findViewById(R.id.button1);
StopB.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub
            Log.e("Pressed", "UNRGSTR");

        }
    } ) ;

    }

}

BRR类

public class BRR extends BroadcastReceiver{
String TAG="DELETE BLOCK";

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO Auto-generated method stub


            //do something 
}

    }

错误 04-26 04:23:28.911: E/AndroidRuntime(516): FATAL EXCEPTION: main Manifest.xml

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

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />
    <uses-permission android:name="android.permission.RECEIVE_SMS"/>

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.deletemessages.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <receiver android:name="BRR">
            <intent-filter android:priority="999">
        <action android:name="android.provider.Telephony.SMS_RECEIVED"></action>
    </intent-filter>
        </receiver>
    </application>

</manifest>

Stacttrace

04-26 04:23:28.911: E/AndroidRuntime(516): FATAL EXCEPTION: main
04-26 04:23:28.911: E/AndroidRuntime(516): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.deletemessages/com.example.deletemessages.MainActivity}: java.lang.NullPointerException
04-26 04:23:28.911: E/AndroidRuntime(516):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1880)
04-26 04:23:28.911: E/AndroidRuntime(516):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
04-26 04:23:28.911: E/AndroidRuntime(516):  at android.app.ActivityThread.access$600(ActivityThread.java:123)
04-26 04:23:28.911: E/AndroidRuntime(516):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
04-26 04:23:28.911: E/AndroidRuntime(516):  at android.os.Handler.dispatchMessage(Handler.java:99)
04-26 04:23:28.911: E/AndroidRuntime(516):  at android.os.Looper.loop(Looper.java:137)
04-26 04:23:28.911: E/AndroidRuntime(516):  at android.app.ActivityThread.main(ActivityThread.java:4424)
04-26 04:23:28.911: E/AndroidRuntime(516):  at java.lang.reflect.Method.invokeNative(Native Method)
04-26 04:23:28.911: E/AndroidRuntime(516):  at java.lang.reflect.Method.invoke(Method.java:511)
04-26 04:23:28.911: E/AndroidRuntime(516):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
04-26 04:23:28.911: E/AndroidRuntime(516):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
04-26 04:23:28.911: E/AndroidRuntime(516):  at dalvik.system.NativeStart.main(Native Method)
04-26 04:23:28.911: E/AndroidRuntime(516): Caused by: java.lang.NullPointerException
04-26 04:23:28.911: E/AndroidRuntime(516):  at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:101)
04-26 04:23:28.911: E/AndroidRuntime(516):  at com.example.deletemessages.MainActivity.<init>(MainActivity.java:17)
04-26 04:23:28.911: E/AndroidRuntime(516):  at java.lang.Class.newInstanceImpl(Native Method)
04-26 04:23:28.911: E/AndroidRuntime(516):  at java.lang.Class.newInstance(Class.java:1319)
04-26 04:23:28.911: E/AndroidRuntime(516):  at android.app.Instrumentation.newActivity(Instrumentation.java:1023)
04-26 04:23:28.911: E/AndroidRuntime(516):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1871)
04-26 04:23:28.911: E/AndroidRuntime(516):  ... 11 more
4

1 回答 1

0

在这里 ：

ComponentName component =new ComponentName(getApplicationContext(), BRR.class);//<<

您正在尝试在调用onCreate或创建 Activity 之前访问上下文。所以把它移到里面onCreate：

ComponentName component;  //<< declare here...
 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // initialize here..
        component =new ComponentName(getApplicationContext(), BRR.class);
于 2013-04-26T04:35:23.007 回答