我需要从>>>> lisitAdaptera onClick方法添加列表项目 donelistadapter ,所以我需要实例化在 listAdaptera 中添加添加列表项目和notifyDatasetchanged()但 donelistadapter 返回null和我的应用程序崩溃,为什么返回null?
public class ListAdapterA extends ArrayAdapter<Abc> {
private Context context;
private String testString = "a";
DoneListAdapter doneListAdapter;
List<Abc> abc;
List<DoneAbc> doneAbc;
public ListAdapter(Context context, List<Abc> cbA) {
super(context, R.layout.list_item, cbA);
this.context = context;
this.abc = cbA;
doneListAdapter = new DoneListAdapter(context,doneAbc);
doneActionHandler = new DoneActionHandler(context);
actionHandler = new ActionHandler(context);
}
private class ViewHolder {
ImageButton abcDoneBtn;
}
@Override
public Abc getItem(int position) {
return abc.get(position);
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public int getViewTypeCount() {
return 2;
}
@Override
public int getItemViewType(int position) {
return (testString == "a") ? 0:1;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
int type = getItemViewType(position);
if (convertView == null) {
if (type == 0){
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.list_item_finished, null);
}else {
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.list_item, null);
}
holder = new ViewHolder();
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
if (type == 0){
holder.abcDoneBtn= (ImageButton)convertView.findViewById(R.id.finished_abc);
holder.abcDoneBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Abc abc = (Abc) getItem(position);
DoneABC doneabc = new DoneAC();
DoneABC.setId(abc.getId());
doneabc.setName(abc.getName());
doneActionHandler.save(doneabc);
doneListAdapter.add(doneabc);
remove(abc);
actionHandler.delete(abc);
notifyDataSetChanged();
doneListAdapter.notifyDataSetChanged();
}
});
}
return convertView;
}
@Override
public void add(Abc abc) {
dreams.add(abc);
notifyDataSetChanged();
super.add(abc);
}
@Override
public void remove(Abc abc) {
dreams.remove(abc);
notifyDataSetChanged();
super.remove(abc);
}
}
Doneadapter:
public class DoneListAdapter extends ArrayAdapter<DoneAbc> {
private Context context;
List<DoneAbc> adoneAbc;
public DoneListAdapter(Context context, List<DoneAbc> doneAbc) {
super(context, R.layout.list_item, doneAbc);
this.context = context;
this.adoneAbc = doneAbc;
}
private class ViewHolder {
}
@Override
public int getCount() {
return adoneAbc.size();
}
@Override
public DoneAbc getItem(int position) {
return adoneAbc.get(position);
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
int type = getItemViewType(position);
if (convertView == null) {
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.list_item, null);
holder = new ViewHolder();
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
return convertView;
}
@Override
public void add(DoneAbc doneAbc) {
adoneAbc.add(doneAbc);
notifyDataSetChanged();
super.add(doneAbc);
}
@Override
public void remove(DoneAbc doneAbc) {
adoneAbc.remove(doneAbc);
notifyDataSetChanged();
super.remove(doneAbc);
}
}
致命例外:主要 过程:com.teamkosas.cloudv05,pid:30693 java.lang.nullpointerexception:尝试调用接口方法'boolean java.util.list.add(java.lang.object)'null对象参考 在com.teamkosas.cloudv05.adapters.donelistadapter.add(donelistadapter.java:123) 在com.teamkosas.cloudv05.adapters.listadaptera上 at android.view.view.performClick(view.java:5697) at android.view.view $ persilClick.run(view.java:22526) 在Android.os.handler.handlecallback(Handler.java:739) 在Android.os.handler.dispatchMessage(Handler.java:95) at android.os.looper.loop(looper.java:158) at android.app.activitythread.main(activityThread.java:7224) 在java.lang.reflect.method.invoke(本机方法)上 在com.android.internal.os.os.zygoteinit $ methodAndargScaller.run(zygoteinit.java:1230) 在com.android.internal.os.os.zygoteinit.main(zygoteinit.java:1120)
您正在通过DoneListAdapter
构造函数中的空列表。
在您的课程中ListAdapterA
替换此行:
doneListAdapter = new DoneListAdapter(context,doneAbc);
与此:
doneListAdapter = new DoneListAdapter(context,new ArrayList<DoneAbc>())