android - 如何制作轮式拾取器

Question

我正在尝试制作像 this 这样的轮式拾取器我试过下载这个项目，但 .zip 下载中包含的唯一文件是 wheel-demo.apk 和 notes.txt。 Notes.txt 没有任何关于如何在 android studio 中使用这个文件的说明。我找到了一篇建议使用 ListViews 来创建相同效果的帖子。我没有自己制作，而是又花了一天时间在互联网上搜索，我找到了源代码 here但是当我将文件导入我的项目时，IDE 显示了很多错误。通过反复试验，我设法修复了除 3 个错误之外的所有错误。很确定我已将相关代码放在下面
主要 Activity .java:

OnWheelScrollListener scrolledListener = new OnWheelScrollListener()
{
    public void onScrollingStarted(WheelView wheel)
    {
        wheelScrolled = true;// "Cannot resolve symbol wheelScrolled
    }

    public void onScrollingFinished(WheelView wheel)
    {
        wheelScrolled = false;// "Cannot resolve symbol wheelScrolled
        updateStatus();
    }
};

// Wheel changed listener
private final OnWheelChangedListener changedListener = new OnWheelChangedListener()
{
    public void onChanged(WheelView wheel, int oldValue, int newValue)
    {
        if (!wheelScrolled)// "Cannot resolve symbol wheelScrolled
        {
            updateStatus();
        }
    }
};
private void initWheel1(int id)
{
    WheelView wheel = (WheelView) findViewById(id);
    wheel.setAdapter(new ArrayWheelAdapter<String>(wheelMenu1)); //cannot resolve method 'setAdapter(com.projectname.ArrayWheelAdapter<Java.lang.String>)
    wheel.setVisibleItems(2);
    wheel.setCurrentItem(0);
    wheel.addChangingListener(changedListener);
    wheel.addScrollingListener(scrolledListener);
}

OnWheelScrollListener.java:

public interface OnWheelScrollListener {
/**
 * Callback method to be invoked when scrolling started.
 * @param wheel the wheel view whose state has changed.
 */
void onScrollingStarted(WheelView wheel);

/**
 * Callback method to be invoked when scrolling ended.
 * @param wheel the wheel view whose state has changed.
 */
void onScrollingFinished(WheelView wheel);}

OnWheelChangedListener.java:

    public interface OnWheelChangedListener {
    /**
     * Callback method to be invoked when current item changed
     * @param wheel the wheel view whose state has changed
     * @param oldValue the old value of current item
     * @param newValue the new value of current item
     */
    void onChanged(WheelView wheel, int oldValue, int newValue);
}

ArrayWheelAdapter.java

    public class ArrayWheelAdapter<T> extends AbstractWheelTextAdapter {

    // items
    private T items[];

    /**
     * Constructor
     * @param context the current context
     * @param items the items
     */
    public ArrayWheelAdapter(Context context, T items[]) {
        super(context);

        //setEmptyItemResource(TEXT_VIEW_ITEM_RESOURCE);
        this.items = items;
    }

    @Override
    public CharSequence getItemText(int index) {
        if (index >= 0 && index < items.length) {
            T item = items[index];
            if (item instanceof CharSequence) {
                return (CharSequence) item;
            }
            return item.toString();
        }
        return null;
    }

    @Override
    public int getItemsCount() {
        return items.length;
    }
}

所有 3 个 .java 文件都已添加到 MainActivity 的导入列表中，认为它可以解决问题，但没有。 谢谢你到目前为止的建议。

Answer 1

您可以只使用 default NumberPicker自 API 11 起包含在 Android 中。您可以使用 NumberPicker#setDisplayedValues 显示您想要的任何字符串。

XML:

<NumberPicker
        android:id="@+id/number_picker"
        android:layout_width="match_parent"
        android:layout_height="180dp" />

Java:

    String[] data = new String[]{"Berlin", "Moscow", "Tokyo", "Paris"};
    picker.setMinValue(0);
    picker.setMaxValue(data.length-1);
    picker.setDisplayedValues(data);

截图: