【单选题】定义类: package utils; public class Rep{ public static String twice (String s){return s+s ;) } 再定义另一个类Demo: l.//insert code here 2.public class Demo{ 3. public static vo...
【单选题】以下代码,哪一行会报错class Example { String str; public Example(){ str = "example"; } public Example(String s){ str = s; }}class Demo extends Example{ }public class Test{ public void f(){ Example ex = new Examp...