オブジェクトが代入可能か調べる

public class AssignableTest{
    public static void main(String args[]){
        String str = new String("ABC");
        StringBuffer strbuf = new StringBuffer("");
        System.out.println(str.getClass().isAssignableFrom(strbuf.getClass()));

        Object obj = new Object();
        Integer integer = new Integer(10);
        System.out.println(obj.getClass().isAssignableFrom(integer.getClass()));
    }
}

false
true