java 不确定如何解决“无法解析构造函数”错误
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Unsure how to resolve "Cannot resolve constructor" error
提问by Ila Icamsab
I am getting an error on a particular fragment (which is one of three on a tabbed activity). The error is:
我在特定片段上遇到错误（这是选项卡式活动中的三个片段之一）。错误是：
Cannot resolve constructor 'ArrayAdapter(layout.OneWayFragmen,int,java.lang.string[])'
I am trying to include and autocomplete field on one fragment of a tabbed activity. The java class in question is below:
我正在尝试在选项卡式活动的一个片段上包含和自动完成字段。有问题的java类如下：
package layout;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import com.example.alibasmaci.maral.R;
/**
* A simple {@link Fragment} subclass.
*/
public class OneWayFragment extends Fragment {
public OneWayFragment() {
// Required empty public constructor
}
public static OneWayFragment newInstance() {
OneWayFragment fragment = new OneWayFragment();
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_one_way, container, false);
String[] cities =
{"Ottawa - Carp CYRP",
"Toronto - Billy Bishop CYYZ",
"Montreal - St. Hubert CYHU"
};
AutoCompleteTextView actvDeparture;
actvDeparture = (AutoCompleteTextView) rootView.findViewById(R.id.actvDeparture);
ArrayAdapter adapter = new ArrayAdapter(this,android.R.layout.select_dialog_item,cities);
actvDeparture.setThreshold(1);
return rootView;
}
}
The error I am referring to is a result of this line:
我所指的错误是这一行的结果：
ArrayAdapter adapter = new ArrayAdapter(this,android.R.layout.select_dialog_item,cities);
Any thoughts on how to fix this?
关于如何解决这个问题的任何想法？
Thanks
谢谢
采纳答案by Vucko
ArrayAdapter's constructor takes the Contextas the first parameter, and you're passing thisfrom Fragment, which essentially means you're passing a Fragmentin this line:
ArrayAdapter 的构造函数将 theContext作为第一个参数，并且您正在传递thisfrom Fragment，这实际上意味着您Fragment在此行中传递 a ：
ArrayAdapter adapter = new ArrayAdapter(this,android.R.layout.select_dialog_item,cities);
What you should do is pass the activity that it's attached to like:
您应该做的是传递它所附加的活动，例如：
ArrayAdapter adapter = new ArrayAdapter(getActivity(),android.R.layout.select_dialog_item,cities);
An even better way to do it is to declare it as a field and initialize it in onAttachmethod like:
一个更好的方法是将它声明为一个字段并在如下onAttach方法中初始化它：
ArrayAdapter adapter;
@Override
public void onAttach(Context context) {
adapter = new ArrayAdapter(context,android.R.layout.select_dialog_item,cities);
}
EDIT: You're also missing this line:
编辑：您还缺少这一行：
actvDeparture.setAdapter(adapter);
回答by Kakey
ArrayAdapter accepts Context for the first parameter and you can pass the context by calling getActivity().
ArrayAdapter 接受 Context 作为第一个参数，您可以通过调用 getActivity() 传递上下文。
ArrayAdapter adapter = new ArrayAdapter(getActivity(),android.R.layout.select_dialog_item,cities);
回答by ΦXoc? ? Пepeúpa ツ
The error is that there is no such constructor like:
错误是没有这样的构造函数，例如：
ArrayAdapter(Fragment, int, T[])
Change the reference thisfor getActivity()so you can get the context propely,
更改参考this的 getActivity()，所以你可以propely获取上下文，
after that it will match the constructor
之后它将匹配构造函数
ArrayAdapter(Context context, int resource, T[] objects)
回答by Andreas
ArrayAdapteris a genericclass. You haven't specified the generic type argument, so you're using it raw, which is bad. It should be ArrayAdapter<String>.
ArrayAdapter是一个泛型类。您尚未指定泛型类型参数，因此您使用的是raw，这很糟糕。应该是ArrayAdapter<String>。
It has 6 constructors:
它有6个构造函数：
ArrayAdapter(Context context, int resource)
ArrayAdapter(Context context, int resource, int textViewResourceId)
ArrayAdapter(Context context, int resource, T[] objects)
ArrayAdapter(Context context, int resource, int textViewResourceId, T[] objects)
ArrayAdapter(Context context, int resource, List<T> objects)
ArrayAdapter(Context context, int resource, int textViewResourceId, List<T> objects)
You method call has this signature:
您的方法调用具有以下签名：
ArrayAdapter(layout.OneWayFragmen,int,java.lang.string[])
That mightfit the 3rd constructor, but only if layout.OneWayFragmenis a Context. Is it?
这可能适合第三个构造函数，但前提layout.OneWayFragmen是Context. 是吗？
