大家好，请问使用百度提供的定位API时候

mLocationClient为空是怎们一回事

运行时抛出异常

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.baidu.location.LocationClient.registerLocationListener(com.baidu.location.BDAbstractLocationListener)' on a null object reference

try {
    mLocationClient = new LocationClient(this);
} catch (Exception e) {
    e.printStackTrace();
}
mLocationClient.registerLocationListener(new MyLocationListener());