嗨，我有以下代码：
public class ContactGridAdapter extends ArrayAdapter<Person> {
private Context mContext;
private ArrayList<Person> mPeople;
private int mThumbs = R.drawable.default_photo_ic;
public ContactGridAdapter(Context context, ArrayList<Person> people){
super(context, R.layout.grid_item_text);
mContext = context;
mPeople = people;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
if (mPeople == null){
return 0;
}else{
return mPeople.size();
}
}
@Override
public Person getItem(int position) {
// TODO Auto-generated method stub
return mPeople.get(position);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
LayoutInflater inflater = (LayoutInflater) mContext
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.grid_item_text, parent, false);
TextView personName = (TextView) view.findViewById(R.id.textItem);
ImageView personThumb = (ImageView) view.findViewById(R.id.iconItem);
personName.setText(mPeople.get(position).fullName);
personThumb.setImageResource(mThumbs);
return view;
}
}
像这样在onPostExecute中从MainActivity调用它。
*** REST OF CODE OMITTED ***
private class RetrieveFriendList extends AsyncTask<String, Void, ArrayList<Person>> {
@Override
protected ArrayList<Person> doInBackground(String... params) {
// TODO Auto-generated method stub
ArrayList<Person> friendList = null;
String resultData = ((new HttpRetriever())).getFriends(myAccount.email, myAccount.passwd);
Log.i("THUMBQOO", resultData);
try {
if(resultData != null){
friendList = (new ContactHandlers()).friendList(resultData);
}else{
friendList = null;
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
Log.e("THUMBQOO - RET FRIEND", "JSON Exception");
}
return friendList;
}
@Override
protected void onPostExecute(final ArrayList<Person> result) {
Log.i("THUMBQOO", result.toString());
if(result != null){
gridView.setAdapter(new ContactGridAdapter(getApplicationContext(), result));
}
}
}
我怎么总是在上面的gridView.setAdapter行上得到java.lang.NullPointerException。
我试图删除适配器中的上下文引用，所以我的代码如下所示：
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
LayoutInflater inflater = (LayoutInflater) mContext
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.grid_item_text, null);
TextView personName = (TextView) view.findViewById(R.id.textItem);
ImageView personThumb = (ImageView) view.findViewById(R.id.iconItem);
personName.setText(mPeople.get(position).fullName);
personThumb.setImageResource(mThumbs);
return view;
}
但是我仍然遇到同样的错误。
我确信通过从网格构造函数中打印一些Log信息来创建ContactGridAdapter对象。
该错误源于geView（）中的某个地方，但是我不确定具体在哪里。
我还100％确保我的ArrayList包含某些内容。我曾尝试像Toast那样敬酒people.get（0）.ObjectVariable
谁能帮助我指出正确的方向？
编辑1：
这是我的LogCat的摘录
12-13 11:17:05.971: E/AndroidRuntime(4722): FATAL EXCEPTION: main
12-13 11:17:05.971: E/AndroidRuntime(4722): java.lang.NullPointerException
12-13 11:17:05.971: E/AndroidRuntime(4722): at com.gelliesmedia.thumbqoo.ContactActivity$RetrieveFriendList.onPostExecute(ContactActivity.java:239)
12-13 11:17:05.971: E/AndroidRuntime(4722): at com.gelliesmedia.thumbqoo.ContactActivity$RetrieveFriendList.onPostExecute(ContactActivity.java:1)
12-13 11:17:05.971: E/AndroidRuntime(4722): at android.os.AsyncTask.finish(AsyncTask.java:631)
12-13 11:17:05.971: E/AndroidRuntime(4722): at android.os.AsyncTask.access$600(AsyncTask.java:177)
12-13 11:17:05.971: E/AndroidRuntime(4722): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
12-13 11:17:05.971: E/AndroidRuntime(4722): at android.os.Handler.dispatchMessage(Handler.java:99)
12-13 11:17:05.971: E/AndroidRuntime(4722): at android.os.Looper.loop(Looper.java:137)
12-13 11:17:05.971: E/AndroidRuntime(4722): at android.app.ActivityThread.main(ActivityThread.java:5041)
12-13 11:17:05.971: E/AndroidRuntime(4722): at java.lang.reflect.Method.invokeNative(Native Method)
12-13 11:17:05.971: E/AndroidRuntime(4722): at java.lang.reflect.Method.invoke(Method.java:511)
12-13 11:17:05.971: E/AndroidRuntime(4722): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
12-13 11:17:05.971: E/AndroidRuntime(4722): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
12-13 11:17:05.971: E/AndroidRuntime(4722): at dalvik.system.NativeStart.main(Native Method)
编辑2：
谢谢大家的建议，但是问题仍然存在。
出于调试目的，这是我所做的：
@Override
protected void onPostExecute(final ArrayList<Person> result) {
StringBuilder sb = new StringBuilder();
sb.append("");
sb.append(result.size());
String rSize = sb.toString();
Log.i("THUMBQOO", result.toString());
Log.i("THUMBQOO", rSize);
Log.i("THUMBQOO", result.get(0).fullName.toString());
/*
* if(result != null){
gridView.setAdapter(new ContactGridAdapter(getApplicationContext(), result));
}*/
}
这就是我从LogCat得到的
12-13 11：49：23.316：I / THUMBQOO（6671）：
[com.gelliesmedia.thumbqoo.models.Person@a7446248，
com.gelliesmedia.thumbqoo.models.Person@a7485d38] <12-13 11：49：23.316：I / THUMBQOO（6671）：2 <12-13 11：49：23.316：I / THUMBQOO（6671）：andwxyz <
基本上表明结果确实不是null。
最佳答案
尝试这个，，
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View row ;
if (convertView == null)
{
LayoutInflater inflater = (LayoutInflater) mContext
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inflater.inflate(R.layout.grid_item_text, null);
TextView personName = (TextView) row.findViewById(R.id.textItem);
ImageView personThumb = (ImageView) row.findViewById(R.id.iconItem);
personName.setText(mPeople.get(position).fullName);
personThumb.setImageResource(mThumbs);
}else {
row = (View) convertView;
}
return row;
}