Unit5：面向对象编程的高级概念类的继承—继承的实现classManagerextendsEmployee{Stringdepartment;publicvoidshowInfo(){showName();System.out.println(“Managerof”+department);}}类的继承—方法的覆盖类的继承—this与super类的继承—继承、隐藏和覆盖示例类的继承—父子类对象转换原则类的继承—方法的重载类的继承—构造函数的重载抽象方法与抽象类Java语言的接口接口的定义接口的定义接口的实现Java语言的包包的声明包的引用内部类与嵌套类内部类（嵌套类）classInnerClass{publicInnerClass(){System.out.println("createinnerclass");}publicvoidshowInformation(){a++;System.out.println("callingmethodofinnerclass&a="+a);}}publicclassOuterClass{inta;publicOuterClass(){a=0;System.out.println("ThisisOuterClass&a="+a);}publicvoiduseInnerClass(){InnerClassanInnerClass=newInnerClass();anInnerClass.showInformation();}publicstaticvoidmain(Stringargs[]){OuterClassanOuterClass=newOuterClass();anOuterClass.useInnerClass();}内部类（嵌套类）匿名内部类匿名内部类