我正在尝试将自定义ArrayList从活动传递到片段，但不明白代码有什么问题。没有错误，但即便是我也无法获得预期的输出。 在努力修复它近3天之后我完全失去了（是的，但我只是一个初学者）。请帮我解决一下。目的是我想将片段用于另一个活动。
这是我的活动类：
public class CityDetailsActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Create a list of City Details
ArrayList<CityDetails> cityDetail = new ArrayList<CityDetails>();
cityDetail.add(new CityDetails("information", "near", "local food", R.drawable.img1, R.drawable.img1, R.drawable.img6));
Bundle args = new Bundle();
args.putParcelableArrayList("key", cityDetail);
CityInformationFragment myFragment = new CityInformationFragment();
myFragment.setArguments(args);
// Set the content of the activity to use the activity_main.xml layout file
setContentView(R.layout.fragment_main);
ViewPager vpPager = (ViewPager) findViewById(R.id.vpPager);
FragmentPagerAdapter adapterViewPager;
adapterViewPager = new CityDetailsPagerAdapter(getSupportFragmentManager());
vpPager.setAdapter(adapterViewPager);
// Give the TabLayout the ViewPager
TabLayout tabLayout = (TabLayout) findViewById(R.id.sliding_tabs);
tabLayout.setupWithViewPager(vpPager);
}
}
我的自定义Parcelable类如下：
public class CityDetails implements Parcelable {
private String mInformation;
private String mNearPlace;
private String mLocalFood;
private int mItemImageResourceId;
private int mNear_place_image_ResourceId;
private int mLocal_food_image_ResourceId;
public CityDetails(String information, String nearPlace, String localFood, int itemImageResourceId
, int near_place_image_ResourceId, int local_food_image_ResourceId) {
mInformation = information;
mNearPlace = nearPlace;
mLocalFood = localFood;
mItemImageResourceId = itemImageResourceId;
mNear_place_image_ResourceId = near_place_image_ResourceId;
mLocal_food_image_ResourceId = local_food_image_ResourceId;
}
@Override
public void writeToParcel(Parcel out, int flags) {
out.writeString(mInformation);
out.writeString(mNearPlace);
out.writeString(mLocalFood);
out.writeInt(mItemImageResourceId);
out.writeInt(mNear_place_image_ResourceId);
out.writeInt(mLocal_food_image_ResourceId);
}
private CityDetails(Parcel in) {
mItemImageResourceId = in.readInt();
mNear_place_image_ResourceId = in.readInt();
mLocal_food_image_ResourceId = in.readInt();
mNearPlace = in.readString();
mLocalFood = in.readString();
mInformation = in.readString();
}
@Override
public int describeContents() {
return 0;
}
// After implementing the `Parcelable` interface, we need to create the
// `Parcelable.Creator<MyParcelable> CREATOR` constant for our class;
// Notice how it has our class specified as its type.
public static final Parcelable.Creator<CityDetails> CREATOR
= new Parcelable.Creator<CityDetails>() {
// This simply calls our new constructor (typically private) and
// passes along the unmarshalled `Parcel`, and then returns the new object!
@Override
public CityDetails createFromParcel(Parcel in) {
return new CityDetails(in);
}
// We just need to copy this and change the type to match our class.
@Override
public CityDetails[] newArray(int size) {
return new CityDetails[size];
}
};
public String getInformation() {
return mInformation;
}
public String getNearPlace() {
return mNearPlace;
}
public String getLocalFood() {
return mLocalFood;
}
public int getItemImageResourceId() {
return mItemImageResourceId;
}
public int getNear_place_image_ResourceId() {
return mNear_place_image_ResourceId;
}
public int getLocal_food_image_ResourceId() {
return mLocal_food_image_ResourceId;
}
}
最后我的片段是：
public class CityInformationFragment extends Fragment {
public CityInformationFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.city_list, container, false);
Bundle bundle = getArguments();
if ((bundle != null)) {
ArrayList<CityDetails> city = getArguments().getParcelable("key");
// Create an {@link WordAdapter}, whose data source is a list of {@link Word}s. The
// adapter knows how to create list items for each item in the list.
CityDetailsAdapter adapter = new CityDetailsAdapter(getActivity(), city);
// Find the {@link ListView} object in the view hierarchy of the {@link Activity}.
// There should be a {@link ListView} with the view ID called list, which is declared in the
// word_list.xml layout file.
ListView listView = (ListView) rootView.findViewById(R.id.city_list);
// Make the {@link ListView} use the {@link WordAdapter} we created above, so that the
// {@link ListView} will display list items for each {@link Word} in the list.
listView.setAdapter(adapter);
}
return rootView;
}
}
修改 这是我的FragmentPagerDapter
public class CityDetailsPagerAdapter extends FragmentPagerAdapter {
final int PAGE_COUNT = 1;
private String tabTitles[] = new String[] { "City Information"};
private Context context;
public CityDetailsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
return new CityInformationFragment();
}
@Override
public CharSequence getPageTitle(int position) {
// Generate title based on item position
return tabTitles[position];
}
@Override
public int getCount() {
return PAGE_COUNT;
}
} 而且，这是我的CityDetailsAdapter：
public class CityDetailsAdapter extends ArrayAdapter<CityDetails> {
// View lookup cache
private static class ViewHolder {
TextView cityInformation;
ImageView city_item_image;
TextView city_near_place_Information;
ImageView city_item_near_place_image;
TextView city_local_food_Information;
ImageView city_item_local_food_image;
}
public CityDetailsAdapter(Context context, ArrayList<CityDetails> cityDetails) {
super(context, 0, cityDetails);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// Get the data item for this position
CityDetails currentCity = getItem(position);
// Check if an existing view is being reused, otherwise inflate the view
ViewHolder viewHolder; // view lookup cache stored in tag
if (convertView == null) {
// If there's no view to re-use, inflate a brand new view for row
viewHolder = new ViewHolder();
LayoutInflater inflater = LayoutInflater.from(getContext());
convertView = inflater.inflate(R.layout.city_list_item, parent, false);
/*Find the TextView and ImageView and set them on the VIewHolder*/
viewHolder.cityInformation = (TextView) convertView.findViewById(R.id.cityInformation);
viewHolder.city_near_place_Information = (TextView) convertView.findViewById(R.id.city_near_place_Information);
viewHolder.city_local_food_Information = (TextView) convertView.findViewById(R.id.city_local_food_Information);
viewHolder.city_item_image = (ImageView) convertView.findViewById(R.id.city_item_image);
viewHolder.city_item_near_place_image = (ImageView) convertView.findViewById(R.id.city_item_near_place_image);
viewHolder.city_item_local_food_image = (ImageView) convertView.findViewById(R.id.city_item_local_food_image);
// Cache the viewHolder object inside the fresh view
convertView.setTag(viewHolder);
} else {
// View is being recycled, retrieve the viewHolder object from tag
viewHolder = (ViewHolder) convertView.getTag();
}
// Populate the data into the template view using the data object
viewHolder.cityInformation.setText(currentCity.getInformation());
viewHolder.city_item_image.setImageResource(currentCity.getItemImageResourceId());
viewHolder.city_near_place_Information.setText(currentCity.getNearPlace());
viewHolder.city_local_food_Information.setText(currentCity.getLocalFood());
viewHolder.city_item_near_place_image.setImageResource(currentCity.getNear_place_image_ResourceId());
viewHolder.city_item_local_food_image.setImageResource(currentCity.getLocal_food_image_ResourceId());
return convertView;
}
尽可能具体地说明我正在犯的错误。因为作为初学者我可能无法理解一些概念，但我会尝试。无论如何，这是我的第一个问题，所以也许我没有说出正确的问题。 我们非常欢迎您的帮助。 感谢。
答案 0 :(得分：1)
问题似乎与您的FragmentPagerAdapter类有关。您没有通过getItem（）方法返回的片段传递任何参数，它只返回片段对象而不传递任何参数。
所以将方法修改为以下
@Override
public Fragment getItem(int position) {
CityInfomationFragment fragment = new CityInformationFragment();
Bundle args = new Bundle();
args.putParcelableArrayList("key", your_array_list);
fragment.setArguments(args);
return fragment;
}
将array_list传递给活动中FragmentPagerAdapter类的构造函数，并使用字段变量保存它并在getItem（）方法中引用它
修改
您在活动中创建的片段实例完全没有任何效果，除非您使用它执行任何片段事务。您可以将该片段实例传递给FragmentPagerAdater并从getItem（）方法返回该实例，以在ViewPager中显示该片段。
答案 1 :(得分：0)
尝试以下行
ArrayList<CityDetails> city = getArguments().getParcelableArrayList("key");