我的 Activity 查询我的解析数据库,然后返回查询的数据。数据以 ListView 中的名称存储。但我不知道如何检查 ListView 是否为空。我希望它发布一条警报,说 ListView 在事件下是空的。这是我的 Activity
public class OfferPage extends Activity {
String obj;
ProgressDialog mProgressDialog;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_offer_page);
Intent i = getIntent();
obj = i.getStringExtra("RestName");
populateList(obj, "Restraunt");
}
private void populateList(final String Value, final String Key) {
ParseQueryAdapter.QueryFactory<ParseObject> factory = new ParseQueryAdapter.QueryFactory<ParseObject>() {
@Override
@SuppressWarnings({ "unchecked", "rawtypes" })
public ParseQuery create() {
ParseQuery query = new ParseQuery("Offers");
query.whereEqualTo(Key, Value);
return query;
}
};
ParseQueryAdapter<ParseObject> adapter = new ParseQueryAdapter<ParseObject>(
this, factory);
adapter.setTextKey("Offer");
adapter.addOnQueryLoadListener(new OnQueryLoadListener<ParseObject>() {
@Override
public void onLoading() {
mProgressDialog = new ProgressDialog(OfferPage.this);
mProgressDialog.setTitle("Searching for Offers");
mProgressDialog.setMessage("Loading...");
mProgressDialog.setIndeterminate(false);
mProgressDialog.show();
}
@Override
public void onLoaded(List<ParseObject> objects, Exception e) {
mProgressDialog.dismiss();
}
});
final ListView listView = (ListView) findViewById(R.id.offerList);
listView.setAdapter(adapter);
}
我的主要问题是,如果列表为空,我似乎无法确定将支票放在哪里。有什么建议吗?
最佳答案
您必须控制适配器是否为空,而不是 ListView ,因为适配器保存值。
if (adapter== null) {
adapter= new ParseQueryAdapter(this,getElements());
eList.setAdapter(adapter);
} else {
adapter.addAll(getElements());
}
关于android - 如何检查Listview是否为空,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25692484/