Spinner:在打开时获取状态或得到通知 [英] Spinner: get state or get notified when opens

问题描述

是否可以知道 Spinner 是打开的还是关闭的?如果有某种用于 Spinner 的 onOpenListener，那就更好了.

Is it possible to know whether a Spinner is open or closed? It would even be better if there was some sort of onOpenListener for Spinners.

我尝试过使用这样的 OnItemSelectedListener:

I've tried using an OnItemSelectedListener like this:

spinnerType.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            executeSomething();

        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {
            Log.d("nothing" , "selected");  
        }

    });

我知道如果选择了某些内容(在 executeSomething() 中)，窗口将关闭.但是，如果我在 Dialog 之外单击，则不会收到通知，这也会关闭微调器

I can know that the window will close if something is selected (in executeSomething()). But I don't get notified if I click outside of the Dialog, which also closes the spinner

推荐答案

观察这些事件的另一种选择是扩展 Spinner 类并使用其方法之一(performClick() 将触发其对话框/弹出窗口)，然后监视包含此自定义 Spinner 的窗口的焦点.这应该为您提供所有可能的完成可能性(对于对话框或下拉模式)所需的关闭事件.

Another option to watch for those events is to extend the Spinner class and use one of its methods(performClick() which will trigger its dialog/popup) followed by monitoring the focus of the window holding this custom Spinner. This should provide you with the wanted closed event for all the possible finishing possibilities(for either the dialog or dropdown mode).

自定义Spinner 类:

public class CustomSpinner extends Spinner {

   /**
    * An interface which a client of this Spinner could use to receive
    * open/closed events for this Spinner. 
    */
    public interface OnSpinnerEventsListener {

        /**
         * Callback triggered when the spinner was opened.
         */
         void onSpinnerOpened(Spinner spinner);

        /**
         * Callback triggered when the spinner was closed.
         */
         void onSpinnerClosed(Spinner spinner);

    }

    private OnSpinnerEventsListener mListener;
    private boolean mOpenInitiated = false;

    // implement the Spinner constructors that you need

    @Override
    public boolean performClick() {
        // register that the Spinner was opened so we have a status
        // indicator for when the container holding this Spinner may lose focus
        mOpenInitiated = true;
        if (mListener != null) {
            mListener.onSpinnerOpened(this);
        }
        return super.performClick();
    }

    @Override
    public void onWindowFocusChanged (boolean hasFocus) {
        if (hasBeenOpened() && hasFocus) {
            performClosedEvent();
        }
    }

    /**
    * Register the listener which will listen for events.
    */
    public void setSpinnerEventsListener(
            OnSpinnerEventsListener onSpinnerEventsListener) {
        mListener = onSpinnerEventsListener;
    }

    /**
     * Propagate the closed Spinner event to the listener from outside if needed.
     */
    public void performClosedEvent() {
        mOpenInitiated = false;
        if (mListener != null) {
            mListener.onSpinnerClosed(this);
        }
    }

    /**
     * A boolean flag indicating that the Spinner triggered an open event.
     * 
     * @return true for opened Spinner 
     */
    public boolean hasBeenOpened() {
        return mOpenInitiated;
    }

}

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