SpinnerAdapter中getView和getDropDownView之间的区别

Question

当您实现SpinnerAdapter时,您将获得getDropDownView,它与getView您需要扩展时的不同之处BaseAdapter.

Answer 1

如果我们查看以下代码,我们在getView和getDropDownView中有name和value数组.

private void initView() {
    SpinnerDropDownAdapter sddadapter = new SpinnerDropDownAdapter(this);
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_spinner_item, sddadapter.name);

    Spinner getViewSP = (Spinner) findViewById(R.id.getview_sp);
    getViewSP.setAdapter(adapter);

    Spinner getViewWDropDownSP = (Spinner) findViewById(R.id.getview_w_drop_down_sp);
    getViewWDropDownSP.setAdapter(sddadapter);
}

static class SpinnerDropDownAdapter extends BaseAdapter implements
        SpinnerAdapter {
    Context context;

    SpinnerDropDownAdapter(Context ctx) {
        context = ctx;
    }

    String[] name = { " One", " Two", " Three", " Four", " Five", " Six",
            " Seven", " Eight" };
    String[] value = { " 1", " 2", " 3", " 4", " 5", " 6", " 7", " 8" };

    @Override
    public int getCount() {
        return name.length;
    }

    @Override
    public String getItem(int pos) {
        // TODO Auto-generated method stub
        return name[pos];
    }

    @Override
    public long getItemId(int arg0) {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        TextView text = new TextView(context);
        text.setTextColor(Color.BLACK);
        text.setText(name[position]);
        return text;
    }

    @Override
    public View getDropDownView(int position, View convertView,
            ViewGroup parent) {
        TextView text = new TextView(context);
        text.setTextColor(Color.BLACK);
        text.setText(value[position]);
        return text;
    }
}

如果没有实现getDropDownView方法,弹出的下拉列表将从getView获取视图.因此,它只会显示名称.

实现getView和getDropDownView时,前者获取名称,后者获取值,静止的微调器将从getview 获取名称,弹出的下拉列表将获得值.

Answer 2

接受的答案似乎有点复杂,所以为了简单起见

• getView - 用户按下微调器之前在微调器上显示的值,其中每个值视图都可以使用convertView参数进行调整

• getDropDownView - 用户按下微调器后用户可以选择的值列表,其中列表中的每个值都可以使用convertView参数进行调整

Answer 3

getView并getDropDownView可以显示不同的布局.

我创建一个Spinner并class ImageTextAdapter extends ArrayAdapter<String>用作适配器.我重写,getView以便它可以显示ImageView和TextView.但是,我不会覆盖getDropDownView.

这是在按下微调器之前的屏幕截图

然后按下微调器.

我使用以下代码初始化微调器.

String[] spinnerTexts = {"Tanzania", "Thailand"};
int[] spinnerImages = {R.drawable.tanzania, R.drawable.thailand};

ArrayAdapter<String> adapter = new ImageTextAdapter(this, spinnerTexts, spinnerImages);

Spinner spinner = (Spinner) findViewById(R.id.spinner);
spinner.setAdapter(adapter);

这是ImageTextAdapter.java

public class ImageTextAdapter extends ArrayAdapter<String> {

    int[] images;

    public ImageTextAdapter(Context ctx, String[] texts, int[] images) {
        super(ctx, android.R.layout.simple_spinner_item, texts);
        this.images = images;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row = getLayoutInflater().inflate(R.layout.row, parent, false);

        TextView textView = (TextView) row.findViewById(R.id.textView);
        textView.setText(getItem(position));

        ImageView imageView = (ImageView) row.findViewById(R.id.imageView);
        imageView.setImageResource(images[position]);

        return row;
    }
}

Answer 4

我们可以这样使用 SpinnerAdapter：

public class FolderSpinnerAdpater extends BaseAdapter implements SpinnerAdapter {
@Override
public int getCount() {
    return 0;
}

@Override
public Object getItem(int position) {
    return null;
}

@Override
public long getItemId(int position) {
    return 0;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    return null;
}
}

在 BaseAdapter.java 中

public View getDropDownView(int position, View convertView, ViewGroup parent) {
    return getView(position, convertView, parent);
}

OverridegetView()和getDropDownView()?return 不同的视图，你会发现不同之处。