java - 安卓java : accessing class that has parentActivity

Question

我有 GPS 监听器类 AppLocationListener，它具有父 Activity GPSSensorActivity(下面未显示)。

我正在尝试使用 AppLocationListener searchLL = new AppLocationListener(); 从另一个类 QuestionSearch 访问 AppLocationListener searchLL.parentActivity = this; 但使用 this 会导致 QuestionSearch 和 GPSSensorActivity 之间的类型不匹配。 .

这是因为无法访问具有父 Activity 的类吗？如何访问AppLocationListener。 QuestionSearch 是我添加到现有代码中的东西，这不是我的原始代码，我正在尝试我是 java 新手，还不完全理解传递数据和链接类/方法.

// AppLocationListener class
import java.util.ArrayList;
...

public class AppLocationListener implements LocationListener {
    public GPSSensorActivity parentActivity;

    public ArrayList<GeoPoint> pointList;

    public void onLocationChanged(Location location) {

}
    public void onProviderDisabled(String s) {
    }
    public void onProviderEnabled(String s) {            
    }

    public void onStatusChanged(String arg0, int arg1, Bundle arg2) {

    }

} 

// QuestionSearch class
import java.util.ArrayList;
...

public class QuestionSearch extends Activity {

 private static final long MINIMUM_DISTANCECHANGE_FOR_UPDATE = 1; // in Meters
 private static final long MINIMUM_TIME_BETWEEN_UPDATE = 5000; // in Milliseconds
 private LocationManager locationManager;

 @Override
 public void onCreate(Bundle savedInstanceState) {

     super.onCreate(savedInstanceState);
     setContentView(R.layout.activity_quizmap);

     locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

     AppLocationListener searchLL = new AppLocationListener();
     searchLL.parentActivity = this;

     ArrayList<GeoPoint> pointList = new ArrayList<GeoPoint>();
     ...
        // add these points to the list
        pointList.add(gMapPoint);
        pointList.add(gMapPoint2);
     pointList.add(gMapPoint3);


        // now set up the location manager and listener
     searchLL.pointList = pointList;
     locationManager.requestLocationUpdates(
                     LocationManager.GPS_PROVIDER, 
                     MINIMUM_TIME_BETWEEN_UPDATE, 
                     MINIMUM_DISTANCECHANGE_FOR_UPDATE,
                     searchLL
     ); 
 }    
}

Answer 1

为了能够在 searchLL.parentActivity = this; 中传递 this，您的 QuestionSearch 应该是 GPSSensorActivity 或应该扩展它。

Is this because it's not possible to access classes that have parent activities?

不，这与此无关，这是一个纯粹的 Java 问题 - 只需在需要的地方传递正确的类即可。