Question

我正在尝试注册广泛的互联网连接和wifi扫描结果，但我收到此错误。“由：java.lang.IllegalArgumentException：Receiver not registered：null”引起。互联网协议广播工作但不是wifi扫描结果。我感谢任何帮助。

MainActivity：

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();
	}

}

Mainfest：

<?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>

Answer 1

您正在BroadcastReceiver

中创建新的（本地）onResume()

BroadcastReceiverListener receiver = new BroadcastReceiverListener();

但是在onPause() receiver中，null引用了未初始化的实例变量unregisterReceiver(receiver); // receiver is null

receiver

因此，要解决问题只需在onCreate()方法中实例化receiver = new BroadcastReceiverListener();

onPause()

然后onResume()和{{1}}都会取消/注册同一个实例。

Answer 2

您不应在 onPause 方法中取消注册接收器。在 onDestroy

中进行

@Override
protected void onDestroy() {
    unregisterReceiver(receiver);
    super.onDestroy();
}

当您转到wifi设置时，您的活动的 onPause 方法会被调用，因此如果您在 onPause 中取消注册接收器，则android系统将无法通知用户关于它给出IllegalArgumentException的原因的更新。

请勿在 onDestroy（）方法

中调用 super.onPause（）

由以下原因引起：java.lang.IllegalArgumentException：Receiver未注册：null

2 个答案: