数组类型某些情况不能直接强转

例如，

class  Son, class Father.

Son extends Father

Son son, Father father

Object[] oa= new Object[]{son};

(Father[])fs=(Father[])oa; //强转失败，classCastException.



Son[] ss =new Son[]{son};

(Father[])fs=(Father[])ss; //成功。