onUpdate() intilized 变量在小部件类的 onReceive 中为空

Question

我在 onUpdate() 方法中初始化一个变量，然后调用 onReceive() 函数，该函数运行良好，但无法访问 onUpdate() 方法中的变量集。这是为什么？这些变量是字符串变量并且被声明为公共的。我错过了什么吗？

public class WidgetTest extends AppWidgetProvider {
public static String ACTION_WIDGET_RECEIVER = "ActionReceiverWidget";
public String state;
public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) 
{
    Log.e("UPDATE", "Start");   
    RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.main);
     state="State_update"

 System.out.println(state);// My variable is initilised
    Intent active = new Intent(context, WidgetTest.class);
    active.setAction(ACTION_WIDGET_RECEIVER);       
    PendingIntent actionPendingIntent = PendingIntent.getBroadcast(context, 0, active, 0);
    remoteViews.setOnClickPendingIntent(R.id.buttonclick, actionPendingIntent);

    super.onUpdate(context, appWidgetManager, appWidgetIds);
    appWidgetManager.updateAppWidget(appWidgetIds, remoteViews);
    Log.e("UPDATE", "End");
}

@Override
public void onReceive(Context context, Intent intent) 
{
   super.onReceive(context, intent);
    Log.e("RECEIVE", "Start 2");
    if (intent.getAction().equals(ACTION_WIDGET_RECEIVER)) 
    {

            Log.e("Test", "My State is  "state);//it gives me null point exception;

    }
   Log.e("RECEIVE", "End");


}

onReceive 中的状态变量给出空点异常

Answer 1

对于AppWidgetReceiver，首先会调用onReceive()，然后根据收到的Action调用onUpdate(...)方法。所以这里你在 onUpdate() 中初始化 state，它会在 onReceive() 之后被调用，因此 onReceive() 中的 state 是 null。