使用Android片段将自定义适配器设置为listview时获取空指针异常
在将自定义适配器设置为listview时,我收到一个空指针异常。 注意,我使用的是Fragment 我正在创建一个具有导航器抽屉的应用程序。滑块菜单的每一项都会引导我们找到一个片段,其中一个片段有一个listview 这是我的社交碎片代码:使用Android片段将自定义适配器设置为listview时获取空指针异常,android,listview,Android,Listview,在将自定义适配器设置为listview时,我收到一个空指针异常。 注意,我使用的是Fragment 我正在创建一个具有导航器抽屉的应用程序。滑块菜单的每一项都会引导我们找到一个片段,其中一个片段有一个listview 这是我的社交碎片代码: private List<Movie> movieList = new ArrayList<Movie>(); private static final String TAG = MainActivity.class.getSimpl
private List<Movie> movieList = new ArrayList<Movie>();
private static final String TAG = MainActivity.class.getSimpleName();
private CustomListAdapter adapter;
private static final String url = "http://api.androidhive.info/json/movies.json";
private ProgressDialog pDialog;
private ListView listView;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_society_fragment, container, false);
listView = (ListView)getActivity().findViewById(R.id.list_societe);
adapter = new CustomListAdapter(getActivity().getBaseContext(),0, movieList);
listView.setAdapter(adapter);
return rootView;
}
public class CustomListAdapter extends ArrayAdapter<Movie> {
private Context context;
private LayoutInflater inflater;
private List<Movie> movieItems;
ImageLoader imageLoader = AppController.getInstance().getImageLoader();
public CustomListAdapter(Context context, int resource, List<Movie> movieItems) {
super(context, resource, movieItems);
this.context = context;
this.movieItems = movieItems;
}
@Override
public int getCount() {
return movieItems.size();
}
@Override
public Movie getItem(int location) {
return movieItems.get(location);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (inflater == null)
inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null)
convertView = inflater.inflate(R.layout.list_row,null);
if (imageLoader == null)
imageLoader = AppController.getInstance().getImageLoader();
NetworkImageView thumbNail = (NetworkImageView) convertView
.findViewById(R.id.thumbnail);
TextView title = (TextView) convertView.findViewById(R.id.title);
TextView rating = (TextView) convertView.findViewById(R.id.rating);
TextView genre = (TextView) convertView.findViewById(R.id.genre);
TextView year = (TextView) convertView.findViewById(R.id.releaseYear);
// getting movie data for the row
Movie m = movieItems.get(position);
// thumbnail image
thumbNail.setImageUrl(m.getThumbnailUrl(), imageLoader);
// title
title.setText(m.getTitle());
// rating
rating.setText("Rating: " + String.valueOf(m.getRating()));
// genre
String genreStr = "";
for (String str : m.getGenre()) {
genreStr += str + ", ";
}
genreStr = genreStr.length() > 0 ? genreStr.substring(0,
genreStr.length() - 2) : genreStr;
genre.setText(genreStr);
// release year
year.setText(String.valueOf(m.getYear()));
return convertView;
}
private List movieList=new ArrayList();
私有静态最终字符串标记=MainActivity.class.getSimpleName();
专用自定义列表适配器;
私有静态最终字符串url=”http://api.androidhive.info/json/movies.json";
私人对话;
私有列表视图列表视图;
@凌驾
创建视图上的公共视图(布局、充气机、视图组容器、,
Bundle savedInstanceState){
视图根视图=充气机。充气(R.layout.activity\u society\u碎片,容器,false);
listView=(listView)getActivity().findViewById(R.id.list_societe);
adapter=新的CustomListAdapter(getActivity().getBaseContext(),0,movieList);
setAdapter(适配器);
返回rootView;
}
CustomListAdapter.Java代码:
private List<Movie> movieList = new ArrayList<Movie>();
private static final String TAG = MainActivity.class.getSimpleName();
private CustomListAdapter adapter;
private static final String url = "http://api.androidhive.info/json/movies.json";
private ProgressDialog pDialog;
private ListView listView;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_society_fragment, container, false);
listView = (ListView)getActivity().findViewById(R.id.list_societe);
adapter = new CustomListAdapter(getActivity().getBaseContext(),0, movieList);
listView.setAdapter(adapter);
return rootView;
}
public class CustomListAdapter extends ArrayAdapter<Movie> {
private Context context;
private LayoutInflater inflater;
private List<Movie> movieItems;
ImageLoader imageLoader = AppController.getInstance().getImageLoader();
public CustomListAdapter(Context context, int resource, List<Movie> movieItems) {
super(context, resource, movieItems);
this.context = context;
this.movieItems = movieItems;
}
@Override
public int getCount() {
return movieItems.size();
}
@Override
public Movie getItem(int location) {
return movieItems.get(location);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (inflater == null)
inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null)
convertView = inflater.inflate(R.layout.list_row,null);
if (imageLoader == null)
imageLoader = AppController.getInstance().getImageLoader();
NetworkImageView thumbNail = (NetworkImageView) convertView
.findViewById(R.id.thumbnail);
TextView title = (TextView) convertView.findViewById(R.id.title);
TextView rating = (TextView) convertView.findViewById(R.id.rating);
TextView genre = (TextView) convertView.findViewById(R.id.genre);
TextView year = (TextView) convertView.findViewById(R.id.releaseYear);
// getting movie data for the row
Movie m = movieItems.get(position);
// thumbnail image
thumbNail.setImageUrl(m.getThumbnailUrl(), imageLoader);
// title
title.setText(m.getTitle());
// rating
rating.setText("Rating: " + String.valueOf(m.getRating()));
// genre
String genreStr = "";
for (String str : m.getGenre()) {
genreStr += str + ", ";
}
genreStr = genreStr.length() > 0 ? genreStr.substring(0,
genreStr.length() - 2) : genreStr;
genre.setText(genreStr);
// release year
year.setText(String.valueOf(m.getYear()));
return convertView;
}
公共类CustomListAdapter扩展了ArrayAdapter{
私人语境;
私人充气机;
私人电影项目清单;
ImageLoader ImageLoader=AppController.getInstance().getImageLoader();
公共CustomListAdapter(上下文上下文、int资源、列表电影项){
超级(上下文、资源、电影项目);
this.context=上下文;
this.movieItems=movieItems;
}
@凌驾
public int getCount(){
返回movieItems.size();
}
@凌驾
公共电影getItem(int位置){
返回电影项目。获取(位置);
}
@凌驾
公共长getItemId(int位置){
返回位置;
}
@凌驾
公共视图getView(int位置、视图转换视图、视图组父视图){
如果(充气器==null)
充气器=(充气器)上下文
.getSystemService(上下文布局\充气机\服务);
if(convertView==null)
convertView=充气机充气(右布局列表,空);
如果(imageLoader==null)
imageLoader=AppController.getInstance().getImageLoader();
NetworkImageView缩略图=(NetworkImageView)convertView
.findviewbyd(R.id.thumboil);
TextView title=(TextView)convertView.findViewById(R.id.title);
TextView评级=(TextView)convertView.findViewById(R.id.rating);
TextView流派=(TextView)convertView.findViewById(R.id.genre);
TextView year=(TextView)convertView.findViewById(R.id.releaseYear);
//正在获取行的电影数据
Movie m=movieItems.get(位置);
//缩略图像
setImageUrl(m.getThumbnailUrl(),imageLoader);
//头衔
title.setText(m.getTitle());
//评级
rating.setText(“rating:+String.valueOf(m.getRating()));
//体裁
字符串genrest=“”;
for(String str:m.getgreen()){
genrest+=str+“,”;
}
genstr=genstr.length()>0?genstr.substring(0,
genstr.length()-2):genstr;
类型。setText(genrest);
//发布年份
year.setText(String.valueOf(m.getYear());
返回视图;
}
}
和HomeActivity.java:
mTitle = mDrawerTitle = getTitle();
mMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(android.R.id.list);
navMenuIcons = getResources().obtainTypedArray(R.array.nav_drawer_icons);
List<Iitem> items = new ArrayList<Iitem>();
items.add(new Header("Sec1"));
items.add(new ListItem(mMenuTitles[0],navMenuIcons.getResourceId(0, -1)));
items.add(new ListItem(mMenuTitles[1],navMenuIcons.getResourceId(1, -1),"29",true));
items.add(new Header("sec2"));
items.add(new ListItem(mMenuTitles[2], navMenuIcons.getResourceId(2, -1),"79",true));
items.add(new ListItem(mMenuTitles[3], navMenuIcons.getResourceId(3, -1),"229",true));
/**
* listener of sliding menu
*/
private void displayView(int position) {
// update the main content by replacing fragments
Fragment fragment = null;
switch (position) {
case 1:
fragment = new SocietyFragment();
break;
case 2:
break;
case 3:
break;
case 4:
break;
case 5:
break;
default:
break;
}
mTitle=mDrawerTitle=getTitle();
mMenuTitles=getResources().getStringArray(R.array.nav\u抽屉\u项目);
mDrawerLayout=(抽屉布局)findViewById(R.id.抽屉布局);
mDrawerList=(ListView)findViewById(android.R.id.list);
navMenuIcons=getResources().obtainTypedArray(R.array.nav_抽屉图标);
列表项=新建ArrayList();
添加(新标题(“第1节”);
添加(新的列表项(mMenuTitles[0],navMenuIcons.getResourceId(0,-1));
添加(新的ListItem(mMenuTitles[1],navMenuIcons.getResourceId(1,-1),“29”,true));
添加(新标题(“第2节”);
添加(新的列表项(mMenuTitles[2],navMenuIcons.getResourceId(2,-1),“79”,true));
添加(新的ListItem(mMenuTitles[3],navMenuIcons.getResourceId(3,-1),“229”,true));
/**
*滑动菜单侦听器
*/
私有void显示视图(内部位置){
//通过替换片段更新主要内容
片段=空;
开关(位置){
案例1:
fragment=新的SocietyFragment();
打破
案例2:
打破
案例3:
打破
案例4:
打破
案例5:
打破
违约:
打破
}
}
logcat.txt文件:
03-16 14:58:05.300:E/AndroidRuntime(3796):在android.app.ActivityThread.access$600(ActivityThread.java:141)看起来listview inflate返回空值。因为你在活动中膨胀。相反,请尝试以下方法:
public void onViewCreated (View view, Bundle savedInstanceState) {
listView = (ListView) view.findViewById(R.id.list_societe);
}
请将代码精简到最低限度,以了解您的问题。请包括logcat。如果是
listView.setAdapter(适配器)代码>抛出错误,这意味着(ListView)getActivity().findViewById(R.id.list_societe)代码>返回null
。片段中是否有R.id.list\u societe
ListView
?是的,在片段XML文件中。请查看我对@kgnkbyl的answerFULL logcat的评论。去掉你的代码,而不是logcat…我尝试了一下,但没有成功:*对于SocietyFragment类型,findViewById(int)方法是未定义的**试试(ListView)view.findViewById(R.id.list\u societe)代码>仅当我声明adapter=new CustomListAdapter(getActivity().getBaseContext(),0,movieList)时才会显示错误;您应该将布局作为参数发送,请尝试以下操作:adapter=newcustomlistadapter(getActivity(),R.layout.your_layout,movieList);