我开发并推出了Android应用程序。它在我的Android手机上工作正常，但它在几台设备上都崩溃了。
*BugSense gives me the following error:*
0 java.lang.NullPointerException
1 at android.widget.ArrayAdapter.init(ArrayAdapter.java:310)
2 at android.widget.ArrayAdapter.(ArrayAdapter.java:128)
3 **at com.challenger.app.ChallengeAdapter.(ChallengeAdapter.java:27)**
4 at com.challenger.app.AllChallenges.fitChallenges(AllChallenges.java:142)
5 at com.challenger.app.AllChallenges$1.onSuccess(AllChallenges.java:108)
import java.util.ArrayList;
import java.util.List;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import com.loopj.android.http.JsonHttpResponseHandler;
import com.loopj.android.http.RequestParams;
public class AllChallenges extends Fragment {
Button loginButton;
ListView listView2, listView1;
TextView textView;
int category = 0;
View view;
List<Challenge> challenge_data;
public AllChallenges(int cat) {
category = cat;
}
public AllChallenges() {
// TODO Auto-generated constructor stub
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onActivityCreated(savedInstanceState);
if(getActivity()!=null){
load();
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
view = inflater.inflate(R.layout.allchallenges, container, false);
if(getActivity()!=null){
load();
}
return view;
}
public void load() {
loadOld();
if (!AppSettings.refreshed[category + 1]) {
update();
}
}
public void loadOld() {
Log.d("Challenge", "Updating " + category);
JSONArray a = AppSettings.loadChallenges(category, getActivity());
if (a != null) {
fitChallenges(makeArray(a));
}
}
public void update() {
Log.d("Challenge", "getChallenges/" + category);
RequestParams a = new RequestParams();
if (AppSettings.logged) {
a.put("fb_id", AppSettings.facebookId);
a.put("fb_authkey", AppSettings.facebookAuthToken);
}
NetworkClient.receiveJSON("getChallenges/" + category, a,
new JsonHttpResponseHandler() {
@Override
public void onSuccess(JSONArray chalList) {
Log.d("Challenge", "Downloaded " + category);
AppSettings.saveChallenges(category, chalList,
getActivity());
fitChallenges(makeArray(chalList));
AppSettings.refreshed[category + 1] = true;
}
});
}
public Challenge[] makeArray(JSONArray list) {
challenge_data = new ArrayList<Challenge>();
try {
for (int i = 0; i < list.length(); i++) {
JSONObject chal = (JSONObject) list.get(i);
String[] arr = {};
if (chal.has("friends"))
arr = JSONArrToArr(chal.getJSONArray("friends"));
Log.e("Boolean", chal.getString("active"));
challenge_data.add(new Challenge(chal.getInt("id"), chal
.getString("title"), chal.getInt("category"), chal
.getInt("taken_by"), arr, chal.getBoolean("active"),
chal.getString("text"), chal.getInt("streak"), chal
.getInt("percentage")));
}
return challenge_data.toArray(new Challenge[challenge_data.size()]);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return null;
}
}
public void fitChallenges(Challenge[] chalArray) {
**ChallengeAdapter adapter = new ChallengeAdapter(getActivity(),
R.layout.list_row, chalArray);** //
listView1 = (ListView) view.findViewById(R.id.listView1);
listView1.setAdapter(adapter);
OnItemClickListener listener = new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Log.i("listener", "am ID" + id + "position " + position);
int n = (int) id;
String title = challenge_data.get(n).toStringArray()[1];
Log.i("listener", "am ID" + id + "position " + position
+ " title " + title);
int people = challenge_data.get(n).peopleInt;
String category = challenge_data.get(n).toStringArray()[0];
String description = challenge_data.get(n).toStringArray()[5];
int streak = challenge_data.get(n).streak;
int percentage = challenge_data.get(n).percentage;
int chal_id = challenge_data.get(n).id;
boolean active = challenge_data.get(n).active;
((AllChallengesPager) getActivity()).showDetailed(chal_id,
title, "" + people, category, active, description, ""
+ streak, "" + percentage);
}
};
listView1.setOnItemClickListener(listener);
}
public String[] JSONArrToArr(JSONArray arr) {
String[] newArr = {};
try {
List<String> list = new ArrayList<String>();
for (int i = 0; i < arr.length(); i++) {
list.add(arr.getString(i));
}
newArr = list.toArray(new String[list.size()]);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return newArr;
}}
public class ChallengeAdapter extends ArrayAdapter<Challenge> {
Context context;
int layoutResourceId;
Challenge data[] = null;
Typeface a;
public ChallengeAdapter(Context context, int layoutResourceId,
Challenge[] data) {
**super(context, layoutResourceId, data);** //in this line code crashes
this.layoutResourceId = layoutResourceId;
this.context = context;
this.data = data;
a = Typeface.createFromAsset(context.getAssets(),
"fonts/roboto_condensed.ttf");
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
ChallengeHolder holder = null;
Challenge challenge = data[position];
if (row == null) {
LayoutInflater inflater = ((Activity) context).getLayoutInflater();
row = inflater.inflate(layoutResourceId, parent, false);
holder = new ChallengeHolder();
holder.imgIcon = (ImageView) row.findViewById(R.id.list_image);
holder.txtTitle = (TextView) row.findViewById(R.id.challenge);
holder.txtPeople = (TextView) row.findViewById(R.id.peopleNumber);
holder.friendThumbs = (LinearLayout) row
.findViewById(R.id.friendThumbs);
row.setTag(holder);
} else {
holder = (ChallengeHolder) row.getTag();
}
holder.friendThumbs.removeAllViews();
for (int i = 0; i < challenge.friendIds.length; i++) {
holder.friendThumbs.addView(createIcon(challenge.friendIds[i],
context));
}
holder.txtTitle.setText(challenge.title);
holder.txtTitle.setTypeface(a);
holder.imgIcon.setImageResource(challenge.icon);
holder.txtPeople.setText(challenge.peopleString);
return row;
}
static class ChallengeHolder {
public LinearLayout friendThumbs;
ImageView imgIcon;
TextView txtTitle;
TextView txtPeople;
}
public ImageView createIcon(String friendID, Context cont) {
ImageView icon = new ImageView(context);
LinearLayout.LayoutParams par = new LinearLayout.LayoutParams(
(int) cont.getResources().getDimension(R.dimen.fbIconSize),
(int) cont.getResources().getDimension(R.dimen.fbIconSize));
par.setMargins(0, 0, 15, 0);
icon.setLayoutParams(par);
Log.e("ID " + friendID, "log");
final String myurl = AppSettings.profilePictureUrl(friendID);
icon.setImageResource(R.drawable.default_fb_icon_small);
((MyApplication) ((Activity) context).getApplication())
.loadImageSimple(myurl, icon);
return icon;
}
}
我猜这个问题的原因是从getActivity方法得到的上下文等于null，但是不知道如何处理这个问题。任何人都可以解释如何解决问题吗？
答案 0 :(得分：1)
我认为onActivityCreated方法会覆盖并实现此代码，其工作正常可能是......
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
if(getActivity()!=null){
load();
}
}
Fragment lifecyle必须阅读此文档Documentation
答案 1 :(得分：0)
你不应该打电话
if(getActivity()!=null){
load();
}
onCreateView中的。
onViewCreated在onCreateView之后和docs
然而，片段的视图层次结构不会附加到其父级 在这一点上。
答案 2 :(得分：0)
在这个阶段，你的片段很可能与你的活动分离，因为这是在外部线程JsonHttpResponseHandler中调用的。
你在这里有一个很好的解释： https://stackoverflow.com/a/11536337/891479
答案 3 :(得分：-1)
我想如果我没记错的话，最好使用getActivity().getApplicationContext()