Question

我必须在一个我必须在Activity中调用的类中使用 BroadcastReceiver 。显然，我必须注册 BroadcastReceiver ，然后我写了这段代码：

    public class MyClassName {

        Context context;
        BroadcastReceiver batteryInfoReceiverLevel;

        public void CheckBatteryLevel() {

        Log.d("App", "I'm in the CheckBatteryLevel");

        context.registerReceiver(batteryInfoReceiverLevel, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));

        batteryInfoReceiverLevel = new BroadcastReceiver() {

            @Override
            public void onReceive(Context context, Intent intent) {

            Log.d("Apps", "I'm in the onReceive");

            int level= intent.getIntExtra(BatteryManager.EXTRA_LEVEL,0);

            if(level <=100) {
//Do something

            }

            else if(level >=100) {
//Do something
            }

            }

            };

        }

    }

当我运行代码时，应用程序崩溃了＃34; Error receiving broadcast Intent { act=android.intent.action.BATTERY_CHANGED flg=0x60000010 (has extras) }并且崩溃线是

context.registerReceiver(batteryInfoReceiverLevel, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));

我该如何解决？

Answer 1

应用程序崩溃，显示“接收广播意图错误
”

由于context为空，因此您需要在调用context之前初始化registerReceiver。初始化时使用类构造函数或从调用Activity传递给CheckBatteryLevel方法。：

public void CheckBatteryLevel(Context aContext) {

context =aContext;
//....your code here...
}

Answer 2

这里有两个问题：

ρяσѕρєяK指出了第一个：

通过向方法CheckBatteryLevel（）或构造函数添加参数来初始化上下文 of MyClass

public class MyClass(Context ctx) {
    context = ctx;
}

其次，您必须在初始化BroadcastReceiver之后调用registerReceiver（..）。或者它将为null并且未注册。

总而言之，这应该做到：

public class MyClassName {

    BroadcastReceiver batteryInfoReceiverLevel;

    public void CheckBatteryLevel(Context ctx) {

        Log.d("App", "I'm in the CheckBatteryLevel");

        batteryInfoReceiverLevel = new BroadcastReceiver() { // init your Receiver

            @Override
            public void onReceive(Context context, Intent intent) {

                Log.d("Apps", "I'm in the onReceive");
                int level= intent.getIntExtra(BatteryManager.EXTRA_LEVEL,0);
                if(level <=100) {
                    //Do something
                } else if(level >=100) {
                    //Do something
                }
            }
        };
        // register your Receiver after initialization 
        ctx.registerReceiver(batteryInfoReceiverLevel,
                  new IntentFilter(Intent.ACTION_BATTERY_CHANGED)); 
    }
}

在非活动类中注册BroadcastReceiver

2 个答案: