ListViewを継承してonTouchEventを実装するとNullPointerException(Android 2.3以前)になるので回避策でgetChildCount使う実装

HogeListView.java

public class HogeListView extends ListView {

    public HogeListView(Context context) {
        super(context);
    }

    public HogeListView(Context context, AttributeSet attrs) {  
        super(context, attrs);  
    }  

    public HogeListView(Context context, AttributeSet attrs, int defStyle) {  
        super(context, attrs, defStyle);  
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        switch (ev.getAction()) {
        case MotionEvent.ACTION_MOVE:
            // task
            break;
        default:
            break;
        }

        if (getChildCount() == 0) {
            return false;
        }

        return super.onTouchEvent(ev);
    }
}

参考
http://stackoverflow.com/questions/12473625/nullpointerexception-at-android-widget-abslistview-contentfitsabslistview-java