如何使用自定义ArrayAdapter对ListFragment进行充气？ 我有两个班“所有者和汽车”。用户将搜索所有者，并使用ListFragments显示一个或所有者。此外，如果用户要点击所有者，则应显示所有者拥有的汽车的详细列表。我创建了以下类/辅助类（CarDetail和OwnerDetail - 这两个类扩展了ListFragment，People扩展了FragmentActivity，CarAdapter和OwnerAdapter自定义适配器，CarAsyncTask和OwnerAsyncTask AsyncTasks，以及扩展活动的Login）。登录类允许用户登录并搜索所有者。当用户登录并进行搜索时，一个或多个所有者应显示在布局的上部。但是，我无法让它显示出来。这是我的代码：
//在07/30 @ 10:50 AM更新 我更新了OwnerAetail onActivityCreated以使用OwnerActivityAdapter。但是，它在为持有者设置TextView时抛出异常。请参阅底部的例外情况。
为简单起见，我只会显示部分文字。
//Car Class
public class Car {
private String _make;
private String _model;
private String _year;
public Car(String make, String model, String year)
{
this._make = make;
this._model = model;
this._year = year;
}
}
//Owner Class
public class Owner {
private String _firstName;
private String _lastName;
private String _carId;
private Car _car;
public Owner(String lName, String fName, String cId, Car car)
{
this._lastName = lName;
this._firstName = fName;
this._carId = cId;
this._car = car;
}
}
package com.mb.carlovers;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
//Car Detail
public class CarDetail extends ListFragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.customize_layout,container,false);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
String[] myCars = {};
super.onActivityCreated(savedInstanceState);
ArrayAdapter<String> carAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_activated_1, myCars);
setListAdapter(carAdapter);
}
}
//OnwerDetail class
public class OwnerDetail extends ListFragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.customize_layout,container, false);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
//Updated on 07/30 @10:50 AM
//Change this class to use the OwnerAsyncTask()
OnwerAsyncTask asynTask = new OnwerAsyncTask();
List<Owner> lt = null;
try {
lt = asynTask.execute("").get();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Owner myOwners[] = lt.toArray(new Owner[lt.size()]);
super.onActivityCreated(savedInstanceState);
OwnerAdapter ownerAdapter = new OwnerAdapter(getActivity(),android.R.layout.simple_list_item_activated_1 , myOwners);
setListAdapter(ownerAdapter);
}
//People where the new Fragment should be created
public class People extends FragmentActivity implements OnClickListener, OnItemSelectedListener {
private Button search;
private EditText etSearchBy, etSearchByID;
private Spinner spOption;
private String selectedOption = null;
private TextView tvErrorMessage;
@Override
protected void onCreate(Bundle arg0) {
super.onCreate(arg0);
setContentView(R.layout.people);
InitializeVariables();
}
private void InitializeVariables()
{
etSearchBy = (EditText) this.findViewById(R.id.etByLastName);
etSearchByID = (EditText) this.findViewById(R.id.etCarID);
spOption = (Spinner) this.findViewById(R.id.spOption);
search = (Button) this.findViewById(R.id.bSearch);
search.setOnClickListener(this);
tvErrorMessage = (TextView) this.findViewById(R.id.tvErrorMessage);
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,R.array.spOptions, android.R.layout.simple_spinner_dropdown_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spOption.setAdapter(adapter);
spOption.setOnItemSelectedListener(this);
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
}
@Override
protected void onPause() {
super.onPause();
}
@Override
public void onClick(View v) {
String searchByName = etSearchBy.getText().toString();
String searchById = etSearchByID.getText().toString();
if(selectedOption == null || selectedOption == "All")
{
if(searchByName.matches("") || searchById.matches(""))
{
tvErrorMessage.setText("You must select a last name and car id");
} else
{
}
} else if(selectedOption == "Name")
{
if(!searchByName.matches(""))
{
try
{
**//Here is the List of information that I need to inflate the fragment with.**
OnwerAsyncTask ownerAsyncTask = new OnwerAsyncTask();
List<Owner> owner = ownerAsyncTask.execute("").get();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} else
{
tvErrorMessage.setText("You must enter the last name of the owner.");
}
} else if (selectedOption == "ID")
{
if(!searchById.matches(""))
{
String st = null;
String d = st;
} else
{
tvErrorMessage.setText("You must enter the car id that you'd like to search.");
}
}
}
//Owner Adapter – (The Car Adapter looks similar to this except the variables name are different.)
public class OwnerAdapter extends ArrayAdapter<Owner> {
private Context context;
private int layoutResourceId;
private Owner data[] = null;
public OwnerAdapter(Context context, int resource, int textViewResourceId,Owner[] data) {
super(context, resource, textViewResourceId, data);
this.context = context;
this.layoutResourceId = resource;
this.data = data;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
OwnerHolder holder = null;
if(row == null)
{
LayoutInflater inflater = ((Activity)context).getLayoutInflater();
row = inflater.inflate(layoutResourceId, parent, false);
holder = new OwnerHolder();
holder.tvFirstName = (TextView) row.findViewById(R.id.tvFirstName);
holder.tvLastName = (TextView) row.findViewById(R.id.tvLastName);
holder.tvCarId = (TextView) row.findViewById(R.id.tvCarID);
row.setTag(holder);
} else
{
holder = (OwnerHolder) row.getTag();
}
Owner item = data[position];
**//Updated on 07/30 @10:50 AM
// Below is where I am getting the exception**
holder.tvFirstName.setText(item.getFirstName().toString());
holder.tvLastName.setText(item.getLastName().toString());
holder.tvCarId.setText(item.getCarId().toString());
return row;
}
static class OwnerHolder
{
TextView tvFirstName;
TextView tvLastName;
TextView tvCarId;
}
}
//Owner AsyncTask –(CarAsyncTask is also similar)
public class OnwerAsyncTask extends AsyncTask<String, Void, List<Owner>> {
private List<Owner> items = null;
@Override
protected List<Owner> doInBackground(String... params) {
try
{
items = new ArrayList<Owner>();
items.add(new Owner("John", "Smith", "1"));
items.add(new Owner("Samantha", "Right", "2"));
items.add(new Owner("Regie", "Miller", "3"));
items.add(new Owner("Mark", "Adam", "4"));
} catch(Exception ex)
{
ex.toString();
}
return items;
}
@Override
protected void onPostExecute(List<Owner> result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
}
}
//My customize Layout for the listfragment
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ListView
android:id="@id/android:list"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
</ListView>
<TextView
android:id="@id/android:empty"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="No record to be displayed." />
</LinearLayout>
//于07/30 @ 10:50 AM更新 //这是例外
07-30 14：18：15.155：E / AndroidRuntime（864）：致命异常：主要 07-30 14：18：15.155：E / AndroidRuntime（864）：java.lang.NullPointerException 07-30 14：18：15.155：E / AndroidRuntime（864）：at com.mb.carlovers.adapter.OwnerAdapter.getView（OwnerAdapter.java:48） 07-30 14：18：15.155：E / AndroidRuntime（864）：在android.widget.AbsListView.obtainView（AbsListView.java:2033） 07-30 14：18：15.155：E / AndroidRuntime（864）：在android.widget.ListView.onMeasure（ListView.java:1127） 07-30 14：18：15.155：E / AndroidRuntime（864）：在android.view.View.measure（View.java:12603） 07-30 14：18：15.155：E / AndroidRuntime（864）：在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:4677） 07-30 14：18：15.155：E / AndroidRuntime（864）：在android.widget.LinearLayout.measureChildBeforeLayout（LinearLayout.java:1369） 07-30 14：18：15.155：E / AndroidRuntime（864）：在android.widget.LinearLayout.measureVertical（LinearLayout.java:660） 07-30 14：18：15.155：E / AndroidRuntime（864）：在android.widget.LinearLayout.onMeasure（LinearLayout.java:553） 07-30 14：18：15.155：E / AndroidRuntime（864）：在android.view.View.measure（View.java:12603） 07-30 14：18：15.155：E / AndroidRuntime（864）：在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:4677） 07-30 14：18：15.155：E / AndroidRuntime（864）：在android.widget.FrameLayout.onMeasure（FrameLayout.java:293） 07-30 14：18：15.155：E / AndroidRuntime（864）：在android.view.View.measure（View.java:12603） 07-30 14：18：15.155：E / AndroidRuntime（864）：在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:4677） 07-30 14：18：15.155：E / AndroidRuntime（864）：在android.widget.LinearLayout.measureChildBeforeLayout（LinearLayout.java:1369）
答案 0 :(得分：0)
@btse就是现货！您只需将空items列表发送到自定义适配器，然后在notifyDataSetChanged()的{{1}}上拨打onPostExecute即可。 Android会在此次通话后处理您的AsyncTask。
当xml中的适配器为空（参考here）时，您甚至可以放置“请搜索所有者”类型的消息：
ListFragment如果您不想留空。
祝你好运！