Question

让我们说这是我的代码，我想根据某些条件将2个不同的视图扩展到listView。

public View getView(int position, View convertView, ViewGroup parent) {
    if (condition) {
        view = layoutInflater.inflate(R.layout.layout1, parent, false);
    } else {
        view = layoutInflater.inflate(R.layout.layout2, parent, false);
    }
    return view;
}

我想使用convertView来回收返回的视图，但是我的适配器将如何知道要回收的两种类型中的哪一种？

Answer 1

答案：

您应该将此方法添加到适配器，这将使适配器将正确的转换视图提供给当前索引。只要您保持与正确类型保持一致，返回的数字并不重要。

ggplot(data, aes(x=xval, y=yval_LWTW, fill=SNP)) +  
             scale_fill_manual(values=c(GG="blue",CC="red",NN="green")) + 
             geom_bar(stat="identity", width=1) + 
             theme(axis.title.x=element_blank()) +
             coord_cartesian(ylim=c(50,90))

Answer 2

您需要在Adapter界面中实现另外两种方法：

/**
 * <p>
 * Returns the number of types of Views that will be created by
 * {@link #getView}. Each type represents a set of views that can be
 * converted in {@link #getView}. If the adapter always returns the same
 * type of View for all items, this method should return 1.
 * </p>
 * <p>
 * This method will only be called when when the adapter is set on the
 * the {@link AdapterView}.
 * </p>
 * 
 * @return The number of types of Views that will be created by this adapter
 */
int getViewTypeCount();
/**
 * Get the type of View that will be created by {@link #getView} for the specified item.
 * 
 * @param position The position of the item within the adapter's data set whose view type we
 *        want.
 * @return An integer representing the type of View. Two views should share the same type if one
 *         can be converted to the other in {@link #getView}. Note: Integers must be in the
 *         range 0 to {@link #getViewTypeCount} - 1. {@link #IGNORE_ITEM_VIEW_TYPE} can
 *         also be returned.
 * @see #IGNORE_ITEM_VIEW_TYPE
 */
int getItemViewType(int position);

即。有两种不同类型的观点：

@Override
public int getItemViewType(int position) {
    if(condition(position)){
        return 0;
    }
    return 1;
}

@Override
public int getViewTypeCount() {
    return 2;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    if(condition(position)){
        //handle first type of view 0
    } else {
        //handle second type of view 1
    }
}

Answer 3

 private class MyAdapter extends ArrayAdapter<String> {



    public MyAdapter(Context context, List<String> list) {
        super(context, 0, list);
    }

    @Override
    public int getItemViewType(int position) {
        return position % 2;
    }

    @Override
    public int getViewTypeCount() {
        return 2;
    }

    @Override
    public View getView(int position, View view, ViewGroup parent) {
        int type = getItemViewType(position);
            if (type == 1){
                view = layoutInflater.inflate(R.layout.layout1, parent, false);
            } else {
                view = layoutInflater.inflate(R.layout.layout2, parent, false);
            }
        return view;
    }

}

Answer 4

您可以解决以下问题：

将两个视图添加为相同布局的子项（item_example.xml）：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/white">
        <View
            android:id="@+id/v_first"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:visibility="gone">
        <View
            android:id="@+id/v_second"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:visibility="gone">
</LinearLayout>

并根据您所需的条件决定在运行时显示哪一个：

@Override
public View getView(int position, View convertView, ViewGroup parent)
{
    View exampleView = convertView;

    if (exampleView == null) {
        LayoutInflater inflater = fragment.getActivity().getLayoutInflater();
        exampleView             = inflater.inflate(R.layout.item_example, parent, false);
    }

    View view1 = exampleView.findViewById(R.id.v_first);
    View view2 = exampleView.findViewById(R.id.v_second);

    if (/* ... show view1 ? ... */) {
        view1.setVisibility(View.VISIBLE);
        view2.setVisibility(View.GONE);
    } else {
        view2.setVisibility(View.VISIBLE);
        view1.setVisibility(View.GONE);
    }
    return exampleView;
}

基本适配器，如何在显示不同视图时使用convertView

4 个答案: