我正在尝试注册广泛的互联网连接和 wifi 扫描结果，但收到此错误。“由以下原因引起：java.lang.IllegalArgumentException：接收器未注册：null”。互联网连接广播有效，但 wifi 扫描结果无效。
我感谢任何帮助。
主要活动：
public class MainActivity extends ActionBarActivity {
BroadcastReceiverListener receiver;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
receiver = new BroadcastReceiverListener();
}
private class BroadcastReceiverListener extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(
android.net.wifi.WifiManager.SCAN_RESULTS_AVAILABLE_ACTION)) {
}
else if (intent.getAction().equals(
android.net.ConnectivityManager.CONNECTIVITY_ACTION)) {
}
}
};
protected void onResume() {
IntentFilter wifi = new IntentFilter();
wifi.addAction(android.net.wifi.WifiManager.SCAN_RESULTS_AVAILABLE_ACTION);
registerReceiver(receiver, wifi);
IntentFilter conn = new IntentFilter();
conn.addAction(android.net.ConnectivityManager.CONNECTIVITY_ACTION);
registerReceiver(receiver, conn);
super.onResume();
}
@Override
protected void onDestroy() {
unregisterReceiver(receiver);
super.onDestroy();
}
}
显现：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.bustracker"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="21" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<!-- Enable to check if the wifi is available -->
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".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>
<activity
android:name=".BCR"
android:label="@string/title_activity_bcr" >
</activity>
</application>
</manifest>
您正在创建一个新的（本地）BroadcastReceiver在你的onResume()
BroadcastReceiverListener receiver = new BroadcastReceiverListener();
但在你的onPause() the receiver指的是未初始化的实例变量null
unregisterReceiver(receiver); // receiver is null
因此，要解决这个问题，只需实例化receiver一旦在你的onCreate() method
receiver = new BroadcastReceiverListener();
然后两个onPause() and onResume()将取消/注册同一实例。
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