java - 为什么 ListView 没有显示在 fragment 中？

Question

我不熟悉如何将项目添加到 fragment 的 ListView ，但我尝试过。它没有显示任何错误。但它也没有在应用程序上显示任何内容。 嗯，我从 youtube 学到了这样做的步骤。它在主要 Activity 类中也完美工作，但在 fragment 类中它不起作用。 所以请帮忙。

项目 ListView :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@android:color/transparent"
    android:paddingLeft="5dp"
    android:paddingRight="5dp"
    android:orientation="vertical"
    >

    <LinearLayout
        android:id="@+id/lyt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" 
        android:minHeight="1px"
        android:gravity="left|top"
        android:padding="2dp"
        android:orientation="horizontal" >

        <TextView
            android:id="@+id/textView1"
            android:layout_width="0dp"
            android:layout_weight="5"
            android:layout_height="wrap_content"
            android:textColor="@color/darker_grey"
            android:gravity="left|top"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="Name"
            android:textStyle="bold"/>

        <TextView
            android:gravity="left|top"
            android:id="@+id/textView3"
            android:layout_width="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:layout_height="wrap_content"
            android:textColor="@color/darker_grey"
            android:paddingLeft="5dp"
            android:paddingRight="10dp"
            android:text=":" />

        <TextView
            android:textStyle="bold"
            android:gravity="left|top"
            android:id="@+id/textView2"
            android:layout_width="0dp"
            android:layout_weight="6"
            android:layout_height="wrap_content"
            android:textColor="@color/darker_grey"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="Medium Text"/>
    </LinearLayout>

</LinearLayout>

ussdz.java:

package com.buckydroid.app.droidcpu;

/**
 * Created by BuckyDroid on 14-06-2016.
 */
public class ussdz
{
    private int id;
    private String USSD;
    private String Description;

    public ussdz(String description, String s) {
        Description = description;
        this.USSD = USSD;
        this.id = id;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUSSD() {
        return USSD;
    }

    public void setUSSD(String USSD) {
        this.USSD = USSD;
    }

    public String getDescription() {
        return Description;
    }

    public void setDescription(String description) {
        Description = description;
    }
}

ussdadaper.java:

package com.buckydroid.app.droidcpu;

import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import java.util.List;


/**
 * Created by BuckyDroid on 14-06-2016.
 */
public class ussdadaper extends BaseAdapter {
    private Context ussds;
    private List<ussdz> ussdlist;

    public ussdadaper(Context ussds, List<ussdz> ussdlist) {
        this.ussds = ussds;
        this.ussdlist = ussdlist;
    }

    @Override
    public int getCount() {
        return ussdlist.size();

    }

    @Override
    public Object getItem(int position) {
        return ussdlist.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View v= View.inflate(ussds,R.layout.item_listview,null);
        TextView ussdcode = (TextView)v.findViewById(R.id.textView1);
        TextView ussddesc = (TextView)v.findViewById(R.id.textView2);
        ussdcode.setText(ussdlist.get(position).getUSSD());
        ussddesc.setText(ussdlist.get(position).getDescription());
        return v;


    }
}

ussd.java( fragment ):

package layout;

import android.app.Activity;
import android.content.Context;
import android.net.Uri;
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.ListView;

import com.buckydroid.app.droidcpu.R;
import com.buckydroid.app.droidcpu.ussdadaper;
import com.buckydroid.app.droidcpu.ussdz;
import com.google.android.gms.tagmanager.Container;

import java.util.ArrayList;
import java.util.List;

/**
 * A simple {@link Fragment} subclass.
 * Activities that contain this fragment must implement the
 * {@link ussd.OnFragmentInteractionListener} interface
 * to handle interaction events.
 * Use the {@link ussd#newInstance} factory method to
 * create an instance of this fragment.
 */
public class ussd 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 ListView listView;
    private ussdadaper ussd;
    private List<ussdz> ussdlist;

    private OnFragmentInteractionListener mListener;

    public ussd() {
        // 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 ussd.
     */
    // TODO: Rename and change types and number of parameters
    public static ussd newInstance(String param1, String param2) {
        ussd fragment = new ussd();
        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


        listView = (ListView)container.findViewById(R.id.listView);
        ussdlist = new ArrayList<>();
        ussdlist.add(new ussdz("*#44336#","Software Version Info"));
        ussdlist.add(new ussdz("*#44336#","Software Version Info"));
        ussdlist.add(new ussdz("*#44336#","Software Version Info"));
        ussdlist.add(new ussdz("*#44336#","Software Version Info"));
        ussdlist.add(new ussdz("*#44336#","Software Version Info"));
        ussdlist.add(new ussdz("*#44336#","Software Version Info"));
        ussdlist.add(new ussdz("*#44336#","Software Version Info"));
        ussdlist.add(new ussdz("*#44336#","Software Version Info"));
        ussd = new ussdadaper(getActivity().getApplicationContext(),ussdlist);


        return inflater.inflate(R.layout.fragment_ussd, container, false);
    }

    // TODO: Rename method, update argument and hook method into UI event

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
    }

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

        public interface OnFragmentInteractionListener {
            public void onFragmentInteractionHome(Uri uri);
            public void openHome(View view);
        }
    }

    /**
     * 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.
     */

Answer 1

替换这一行: 列表=( ListView ) Container.findViewById(R.id.TaskListView);

将上面的行替换为下面的代码: list = (ListView) getView().findViewById(R.id.TaskListView);