問題

使用Android SDK自帶的Spinner控件時(shí),如果當(dāng)前已經(jīng)選中了一項(xiàng),再次點(diǎn)開Spinner的下拉菜單并選中相同一項(xiàng)時(shí),不會(huì)觸發(fā)OnItemSelectedListener
的onItemSelected()回調(diào)方法,因此無法獲知用戶再次選中了相同項(xiàng).一般情況下,如果用戶選中相同項(xiàng),我們確實(shí)不需要做任何操作,因此也就不關(guān)心該項(xiàng)是否再次
被用戶選擇.但是有些時(shí)候,仍需要獲取這樣的監(jiān)聽.比如一個(gè)Spinner的菜單是本日,本周,本月,自定義時(shí),當(dāng)用戶選中自定義時(shí)間段后,想再次改變
自定義的時(shí)間段,此時(shí)Spinner并不能觸發(fā)再次點(diǎn)擊自定義項(xiàng)的回調(diào).問題由此而來.

解決辦法

網(wǎng)上有很多相關(guān)解決辦法,還有說不用Spinner轉(zhuǎn)而用PopupWindow+ListView手動(dòng)實(shí)現(xiàn)一個(gè)的.目前看來一下方法最簡單:

使用自定義的ReSpinner,繼承自Spinner.當(dāng)相同項(xiàng)被選中時(shí),手動(dòng)觸發(fā)OnItemSelectedListener的onItemSelected()方法.代碼如下:

    import android.content.Context;
    import android.util.AttributeSet;
    import android.widget.Spinner;
    
    public class ReSpinner extends Spinner {
        public boolean isDropDownMenuShown=false;//標(biāo)志下拉列表是否正在顯示
    
        public ReSpinner(Context context) {
            super(context);
        }
    
        public ReSpinner(Context context, AttributeSet attrs) {
            super(context, attrs);
        }
    
        public ReSpinner(Context context, AttributeSet attrs, int defStyle) {
            super(context, attrs, defStyle);
        }
    
        @Override
        public void
        setSelection(int position, boolean animate) {
            boolean sameSelected = position == getSelectedItemPosition();
            super.setSelection(position, animate);
            if (sameSelected) {
                // 如果選擇項(xiàng)是Spinner當(dāng)前已選擇的項(xiàng),則 OnItemSelectedListener并不會(huì)觸發(fā),因此這里手動(dòng)觸發(fā)回調(diào)
                getOnItemSelectedListener().onItemSelected(this, getSelectedView(), position, getSelectedItemId());
            }
        }
    
        @Override
        public boolean performClick() {
            this.isDropDownMenuShown = true;
            return super.performClick();
        }
    
        public boolean isDropDownMenuShown(){
            return isDropDownMenuShown;
        }
    
        public void setDropDownMenuShown(boolean isDropDownMenuShown){
            this.isDropDownMenuShown=isDropDownMenuShown;
        }
    
        @Override
        public void
        setSelection(int position) {
            boolean sameSelected = position == getSelectedItemPosition();
            super.setSelection(position);
            if (sameSelected) {
                getOnItemSelectedListener().onItemSelected(this, getSelectedView(), position, getSelectedItemId());
            }
        }
    
        @Override
        public void onDetachedFromWindow() {
            super.onDetachedFromWindow();
        }
    }

相關(guān)參考

How can I get an event in Android Spinner when the current selected item is selected again?
原文地址 http://www.trojx.me/2017/02/17/spinner-reselect/