android - 如何在android中的Fragment中填写自定义列表？

Question

我有一个 fragment ，我想在其中创建一个自定义 ListView ，但是当我将参数发送到适配器时，它给我错误。

这是我在 Fragment 中的代码..

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fragment_list, container, false);

    TextView tv = (TextView) v.findViewById(R.id.textView1);

    CustomAdapter arrayAdapter = new CustomAdapter(getActivity(), R.layout.search_catagory_list, prgmImages, prgmNameList);
    lv = (ListView) v.findViewById(R.id.listView);

    lv.setAdapter(arrayAdapter);
    return v;
}

这是我的 MainHome.java

package com.example.yasee.bitescene.Fragments;

import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import android.widget.TextView;

import com.example.yasee.bitescene.R;
import com.example.yasee.bitescene.adapter.CustomAdapter;

import java.util.ArrayList;

public class MainHome extends Fragment {
    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";
    private String mParam1;
    private String mParam2;

ListView lv;
public static int [] prgmImages={R.drawable.one,R.drawable.two,R.drawable.three,R.drawable.four,R.drawable.five};
public static String [] prgmNameList={"TRULY RANDOM","TEX MEX","BBQ","BRUNCH","SUSHI"};

private OnFragmentInteractionListener mListener;

public MainHome() {

}

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

    View v = inflater.inflate(R.layout.fragment_list, container, false);

    TextView tv = (TextView) v.findViewById(R.id.textView1);

    CustomAdapter arrayAdapter = new CustomAdapter(getActivity(), R.layout.search_catagory_list, prgmImages, prgmNameList);
    lv = (ListView) v.findViewById(R.id.listView);

    lv.setAdapter(arrayAdapter);
    return v;
}

public static MainHome newInstance(String param1, String param2) {
    MainHome fragment = new MainHome();
    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);
    }
}


public void onButtonPressed(Uri uri) {
    if (mListener != null) {
        mListener.onFragmentInteraction(uri);
    }
}

@Override
public void onAttach(Context context) {
    super.onAttach(context);
    if (context instanceof OnFragmentInteractionListener) {
        mListener = (OnFragmentInteractionListener) context;
    } else {
        throw new RuntimeException(context.toString()
                + " must implement OnFragmentInteractionListener");
    }
}

@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);
}
}

它显示这样的错误..

这是我的适配器代码...

package com.example.yasee.bitescene.adapter;



import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import com.example.yasee.bitescene.Fragments.MainHome;
import com.example.yasee.bitescene.R;
import com.example.yasee.bitescene.Search;

import java.util.ArrayList;

public class CustomAdapter extends BaseAdapter {
    String [] result;
    Context context;
    int [] imageId;
    private static LayoutInflater inflater=null;

public CustomAdapter(Activity activity, int search_catagory_list, int[] prgmImages, String[] prgmNameList) {
    // TODO Auto-generated constructor stub
    result=prgmNameList;
    context=activity;
    imageId=prgmImages;
    inflater = ( LayoutInflater )context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

@Override
public int getCount() {
    // TODO Auto-generated method stub
    return result.length;
}

@Override
public Object getItem(int position) {
    // TODO Auto-generated method stub
    return position;
}

@Override
public long getItemId(int position) {
    // TODO Auto-generated method stub
    return position;
}

public class Holder
{
    TextView tv;
    ImageView img;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    // TODO Auto-generated method stub
    Holder holder=new Holder();
    View rowView;
    rowView = inflater.inflate(R.layout.search_catagory_list, null);
    holder.tv= (TextView) rowView.findViewById(R.id.textView1);
    holder.img=(ImageView) rowView.findViewById(R.id.imageView1);
    holder.tv.setText(result[position]);
    holder.img.setImageResource(imageId[position]);
    rowView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Toast.makeText(context, "You Clicked "+result[position], Toast.LENGTH_LONG).show();
        }
    });
    return rowView;
}

}

我的错误是...

06-13 07:31:00.399 3569-3569/com.example.yasee.bitescene E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.yasee.bitescene, PID: 3569 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.yasee.bitescene/com.example.yasee.bitescene.Search}: java.lang.NullPointerException at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) at android.app.ActivityThread.access$800(ActivityThread.java:135) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5017) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.NullPointerException at com.example.yasee.bitescene.Fragments.MainHome.onCreateView(MainHome.java:44) at android.app.Fragment.performCreateView(Fragment.java:1700) at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:890) at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062) at android.app.BackStackRecord.run(BackStackRecord.java:684) at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447) at android.app.Activity.performStart(Activity.java:5240) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2168) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)  at android.app.ActivityThread.access$800(ActivityThread.java:135)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:136)  at android.app.ActivityThread.main(ActivityThread.java:5017)  at java.lang.reflect.Method.invokeNative(Native Method)  at java.lang.reflect.Method.invoke(Method.java:515)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)  at dalvik.system.NativeStart.main(Native Method) 

Answer 1

lv 似乎为空，导致 NullPointerException。

确保 ListView 的 id 实际上设置为 listView，因为它在下面的行中是预期的。还要确保它在布局 fragment_list

内

lv = (ListView) v.findViewById(R.id.listView);