最后一步代码五如何实现(语言-java)

class Telephone {
String brand, number;
double dialledTime;
double rate;
Telephone(String b, String n) {
brand = b;
​number = n;
}

String getBrand( ) { return brand; }
String getNumber( ) { return number; }
代码1 //返回费率值
double getDialledTime( ) { return dialledTime; }
void setBrand(String b) {
brand = b;
}
void setNumber(String n) {
代码2 // 设置电话号码
}
void setRate(double r) {
rate = r;
}
void setDialledTime(double d) {
dialledTime = d;
}
double callCost( ) {
return dialledTime * rate;
}
void display( ) {
​System.out.println("电话品牌: "+ brand +" 电话号码: "+ number);
System.out.println("通话时间: "+ dialledTime +" 费率: "+ rate);
System.out.println("话费: "+ callCost( ));
}
}
class Mobilephone extends Telephone {
String network;
double receivedTime;
Mobilephone(String b, String num, String net) {
​​super(b, num);
​network = net;
}
String getNetwork( ) { return network; }
double getReceivedTime( ) { return receivedTime; }
void setNetwork(String n) {
network = n;
}
void setReceivedTime(double d) {
代码3 //设置被叫时间
}
double callCost( ) {
return (dialledTime + 0.5*receivedTime) * rate;
}
void display( ) {
​System.out.println("电话品牌: "+ brand +" 电话号码: "+ number
​​ +" 网络: "+ network);
System.out.println("主叫时间: "+ dialledTime +" 被叫时间: " +
​​ receivedTime +" 费率: "+ rate);
System.out.println("话费: "+ callCost( ));
}
}
public class Inheritance {
public static void main(String[] args) {
​Telephone tel;
​Mobilephone mobile;
​tel = new Telephone("TCL", "8309600");
​mobile = new Mobilephone("Nokia", "13007091010","CDMA");
​tel.setRate(0.2);
​tel.setDialledTime(150);
​mobile.setRate(0.4);
​代码4 //设置主叫时间为80
mobile.setReceivedTime(120);
​tel.display( );
System.out.println( );
​代码5 //显示移动电话的信息
}
}

mobile.display( );