onItemClick de访问级别问题

public class ChooseAreaActivity extends Activity {
 public static final int LEVEL_PROVINCE = 0;
 public static final int LEVEL_CITY = 1;
 public static final int LEVEL_COUNTY = 2;
 ......
 private List provinceList;
 private List cityList;
 private List countyList;
 private Province selectedProvince;
 private City selectedCity;
 /**
 * 当前选中的级别
 */
 private int currentLevel;
@Override
protected void onCreate(Bundle saveInstanceState) {
    super.onCreate(saveInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.choose_area);
    .......
    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> arg0, View view, int index, long arg3) {
            if (currentLevel == LEVEL_PROVINCE) {
                selectedProvince = provinceList.get(index);
                queryCities();
            } else if (currentLevel == LEVEL_CITY) {
                selectedCity = cityList.get(index);
                queryCounties();
            }
        }
    });
    queryProvinces();//加载省级数据
}

以上代码我是按照书上敲的，其中有一点我不理解：类中的3个常量 LEVEL_PROVINCE,LEVEL_CITY,LEVEL_COUNTY,如何在点击一个ListVIew的item的时候知道我是在点击省级别、市级别或是县级别的item？_在onItemClick方法中有判断语句if（currentlevel ==..),这个currentlevel是哪里确定的？