java - 如何在一个 fragment 中制作多个卡片 View

Question

我正在尝试以编程方式在 fragment 中创建新的卡片 View ，并将它们添加到已在 xml 中定义的线性布局中。我尝试过这样做，卡片不会出现。请帮忙。 cardviews not showing up in fragment

package com.example.jberroa.senior_design;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.widget.CardView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;


/**
* A simple {@link Fragment} subclass.
* Activities that contain this fragment must implement the
* {@link Overview.OnFragmentInteractionListener} interface
* to handle interaction events.
* Use the {@link Overview#newInstance} factory method to
* create an instance of this fragment.
*/


public class Overview extends Fragment {
    // TODO: Rename parameter arguments, choose names that match
    // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";

    // TODO: Rename and change types of parameters
    private String mParam1;
    private String mParam2;

    private OnFragmentInteractionListener mListener;

    public Overview() {
        // Required empty public constructor
    }

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @param param1 Parameter 1.
     * @param param2 Parameter 2.
     * @return A new instance of fragment Overview.
     */
    // TODO: Rename and change types and number of parameters
    public static Overview newInstance(String param1, String param2) {
        Overview fragment = new Overview();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        // Inflate the layout for this fragment
        View v=inflater.inflate(R.layout.fragment_overview, container, false);
        CardView.LayoutParams params = new CardView.LayoutParams(
                CardView.LayoutParams.WRAP_CONTENT,
                180);
        params.setMargins(10,10,10,100);
        LinearLayout l = (LinearLayout)v.findViewById(R.id.ov);

        for (int i =0;i<10;i++) {
            CardView valueTV = new CardView(container.getContext());
            valueTV.setLayoutParams(params);
            l.addView(valueTV);
        }

        return v;
    }

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteraction(uri);
        }
    }


    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    /**
     * This interface must be implemented by activities that contain this
     * fragment to allow an interaction in this fragment to be communicated
     * to the activity and potentially other fragments contained in that
     * activity.
     * <p>
     * See the Android Training lesson <a href=
     * "http://developer.android.com/training/basics/fragments/communicating.html"
     * >Communicating with Other Fragments</a> for more information.
     */
    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(Uri uri);
    }
}

Answer 1

替换

CardView.LayoutParams params = new CardView.LayoutParams(
            CardView.LayoutParams.WRAP_CONTENT,
            180);

与

   LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                    180);

如果cardview内没有内容，则“wrap_content”大小变为0。这就是cardview不显示在 View 中的原因