将当前ListView与带有ListView的自定义适配器集成以允许多个视图

Question

我当前的项目包括一个带自定义适配器的ListView。但是，我现在有兴趣为ListView添加多种类型的视图，但经过多次尝试后，我无法将两个代码源添加到一起以成功集成它们。

有关多个视图的ListView文章：ListView Article for multiple views

我当前代码中的自定义适配器从另一个名为getData的类中检索数据，该类由＆＃34; data＆＃34;引用。

文章中的代码（包含多个视图的ListView）：

public class MultipleItemsList extends ListActivity {

private MyCustomAdapter mAdapter;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mAdapter = new MyCustomAdapter();
    for (int i = 1; i < 50; i++) {
        mAdapter.addItem("item " + i);
        if (i % 4 == 0) {
            mAdapter.addSeparatorItem("separator " + i);
        }
    }
    setListAdapter(mAdapter);
}

private class MyCustomAdapter extends BaseAdapter {

    private static final int TYPE_ITEM = 0;
    private static final int TYPE_SEPARATOR = 1;
    private static final int TYPE_MAX_COUNT = TYPE_SEPARATOR + 1;

    private ArrayList mData = new ArrayList();
    private LayoutInflater mInflater;

    private TreeSet mSeparatorsSet = new TreeSet();

    public MyCustomAdapter() {
        mInflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    public void addItem(final String item) {
        mData.add(item);
        notifyDataSetChanged();
    }

    public void addSeparatorItem(final String item) {
        mData.add(item);
        // save separator position
        mSeparatorsSet.add(mData.size() - 1);
        notifyDataSetChanged();
    }

    @Override
    public int getItemViewType(int position) {
        return mSeparatorsSet.contains(position) ? TYPE_SEPARATOR : TYPE_ITEM;
    }

    @Override
    public int getViewTypeCount() {
        return TYPE_MAX_COUNT;
    }

    @Override
    public int getCount() {
        return mData.size();
    }

    @Override
    public String getItem(int position) {
        return mData.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;
        int type = getItemViewType(position);
        System.out.println("getView " + position + " " + convertView + " type = " + type);
        if (convertView == null) {
            holder = new ViewHolder();
            switch (type) {
                case TYPE_ITEM:
                    convertView = mInflater.inflate(R.layout.item1, null);
                    holder.textView = (TextView)convertView.findViewById(R.id.text);
                    break;
                case TYPE_SEPARATOR:
                    convertView = mInflater.inflate(R.layout.item2, null);
                    holder.textView = (TextView)convertView.findViewById(R.id.textSeparator);
                    break;
            }
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder)convertView.getTag();
        }
        holder.textView.setText(mData.get(position));
        return convertView;
    }

}

public static class ViewHolder {
    public TextView textView;
}
}

当前代码（带自定义适配器的ListView）：

FragmentA.java

package com.example.newsapp;

public class FragmentA extends Fragment{

getData data = getData.getMyData();

public Integer ArticleID;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    View V = inflater.inflate(R.layout.fragment_a, container, false);

    ListView listView = (ListView)V.findViewById(R.id.list)

      CustomList adapter = new
            CustomList(getActivity(), data.Headline.toArray(new String[data.Headline.size()]), data.Description.toArray(new String[data.Description.size()]), data.BitmapList.toArray(new Bitmap[data.BitmapList.size()]), data.ArticleID.toArray(new Integer[data.ArticleID.size()]));     
      listView.setAdapter(adapter);
      listView.setOnItemClickListener(this); //Removed on click item event code.

    return V;

}

CustomList.java

package com.example.newsapp;

public class CustomList extends ArrayAdapter<String>{
private final Activity context;
private final String[] titleId;
private final String[] descriptionId;
private final Bitmap[] pictureid;

public CustomList(Activity context,
String[] Headline, String[] Description, Bitmap[] BitmapList, Integer[] ArticleID) {
super(context, R.layout.single_row, Headline);
this.context = context;
this.titleId = Headline;
this.descriptionId = Description;
this.pictureid = BitmapList;

}
@Override
public View getView(int position, View view, ViewGroup parent) {
LayoutInflater inflater = context.getLayoutInflater();
View rowView= inflater.inflate(R.layout.single_row, null, true);

TextView txtTitle = (TextView) rowView.findViewById(R.id.tvTitle);
TextView txtDescription = (TextView) rowView.findViewById(R.id.tvDescription);
ImageView imageView = (ImageView) rowView.findViewById(R.id.ivIcon);

txtTitle.setText(titleId[position]);
txtDescription.setText(descriptionId[position]);
imageView.setImageBitmap(pictureid[position]);
return rowView;
}

}

修改

public class CustomList extends ArrayAdapter<String>{

private final Activity context;
private final String[] titleId;
private final String[] descriptionId;
private final Bitmap[] pictureid;

public CustomList(Activity context,
String[] Headline, String[] Description, Bitmap[] BitmapList, Integer[] ArticleID) {
super(context, R.layout.single_row, Headline);
this.context = context;
this.titleId = Headline;
this.descriptionId = Description;
this.pictureid = BitmapList;

}

@Override
public View getView(int position, View view, ViewGroup parent) {
int viewType = getItemViewType(position);
View rowView = null;
switch(viewType) {
case 0:

    LayoutInflater inflater = context.getLayoutInflater();
    rowView= inflater.inflate(R.layout.single_row, null, true);

    TextView txtTitle = (TextView) rowView.findViewById(R.id.tvTitle);
    TextView txtDescription = (TextView) rowView.findViewById(R.id.tvDescription);
    ImageView imageView = (ImageView) rowView.findViewById(R.id.ivIcon);

    txtTitle.setText(titleId[position]);
    txtDescription.setText(descriptionId[position]);
    imageView.setImageBitmap(pictureid[position]);

case 1:

    LayoutInflater inflater2 = context.getLayoutInflater();
    rowView= inflater2.inflate(R.layout.single_row_loadmore, null, true);
}
    return rowView;
}

@Override
public int getViewTypeCount() {
    return 2; // TODO make this a static final
}

@Override
public int getItemViewType(int position) {
    return position % 2; // 0 or 1
}

}

Answer 1

首先，请稍等一下：您应该创建一个封装标题，描述等的类，并使用这些对象的数组/集合来支持您的适配器。它比管理许多不同的事物要容易得多，特别是如果有一天你决定需要文章的另一个属性（例如，它的类别）。

class Article {
    int id;
    String headline;
    String description;
    Bitmap picture;
}

关于ListView，魔术发生在方法getItemViewType()和getViewTypeCount()中。在getViewTypeCount()中，您返回最大行类型数 - 您发布的文章使用两种行类型，因此返回2。在getItemViewType()中，您返回的值介于0和（viewTypeCount - 1）之间 - 在文章中，他的实现可以返回0或1，因为他的viewTypeCount是2。< / p>

您如何确定哪种行类型适用于每个项目完全取决于您。例如，如果您想在每一行上简单地替换视图类型，则可以执行以下操作：

@Override
public int getViewTypeCount() {
    return 2; // TODO make this a static final
}

@Override
public int getItemViewType(int position) {
    return position % 2; // 0 or 1
}

在其他应用程序中，您可能会检查给定位置的项目，以帮助您确定getItemViewtype()中应返回的内容。

此功能存在的原因是getView()提供了一个参数（称为convertView），该参数是已被回收的行。为了给你一个合适的convertView，ListView需要首先知道它是什么行类型。如果要为具有多种行类型的适配器实现getView()，通常看起来像这样：

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    int viewType = getItemViewType(position);
    switch(viewType) {
    case 0:
        return setUpOneViewType(position, convertView, parent);
    case 1:
        return setUpAnotherViewType(position, convertView, parent);
    }
}

请注意，switch语句的大小写对应于可以从getItemViewType()返回的可能值。这些可能是static final成员。

我强烈建议您观看The World of ListView。该视频介绍了此主题以及如何在适配器实现中正确使用convertView。