Android getContentResolver NullPointerException

Question

我是Android新手。调用getContentResolver()函数时，我总是得到NullPointerException。我不知道为什么。代码如下：

@EActivity(R.layout.activity_job_details)
@OptionsMenu(R.menu.main)
public class JobDetailsActivity extends ActionBarActivity {
    @Extra
    Job jobObject;

    @ViewById
    ListView lwPickups;

    PickupAdapter adapter;

    @AfterViews
    public void afterViews() {
            initActionBar();

            adapter = new PickupAdapter(JobDetailsActivity.this,
                            R.layout.row_pickup, R.id.twPickup, jobObject.getPickups());
            lwPickups.setAdapter(adapter);
    }


    private void initActionBar() {
            ActionBar actionBar = getSupportActionBar();
            actionBar.setTitle(jobObject.getDesc());
            actionBar.setDisplayHomeAsUpEnabled(true);
            actionBar.setHomeButtonEnabled(true);

    }

然后我尝试在同一个类中运行查询事件：

    boolean result=queryEvent("123",JobDetailsActivity.this);
    @SuppressLint("NewApi")
    public boolean queryEvent(String event_id,Context context) {
            String[] projection= new String[]{Events.TITLE};
            ContentResolver contentResolver=context.getContentResolver(); // NullPointerException
            Cursor calCursor=contentResolver.query(Events.CONTENT_URI, projection, Events._ID+"="+event_id, null, null);
            if(calCursor.moveToFirst()){
                    do{
                            String id = calCursor.getString(0);
                            if(id==event_id){
                                    return true;
                            }
                    }while(calCursor.moveToNext());
            }
            return false;
    }

}

有人可以提供帮助吗？是否导致在创建活动之前无法访问getContentResolver（）？如果是这样，在这种情况下，我应该在哪里放置getContentResolver（），因为我使用@EActivity（R.layout.activity_job_details）？感谢