java(super关键字)

 

 

class A{
 int x,y;
 A(){
  x=100;
  y=200;
 }
 A(int x,int y){
  this.x=x;
  this.y=y;
 }
}
class B extends A{
 int z;
 B(int x,int y){
  super(x,y);
  z=300;
 }
 B(){
  super();
  z=800;
 }
 public void f(){
  System.out.printf("x=%d,y=%d,z=%d\n",x,y,z);
 }
}
public class Example5_6{
 public static void main(String args[]){
  B b1=new B(10,20);
  b1.f();
  B b2=new B();
  b2.f();
 }
}

 

class Bank{
 int savedMoney;
 int year;
 double interest;
 public double computerInterest(){
  interest=year*0.035*savedMoney;
  System.out.printf("%d元存在银行%d年的利息：%f元\n",savedMoney,year,interest);
  return interest;
 }
}
class ConstructionBank extends Bank{
 double year;
 public double computerInterest(){
  super.year=(int)year;
  double remainNumber=year-(int)year;
  int day=(int)(remainNumber*1000);
  interest=super.computerInterest()+day*0.0001*savedMoney;
  System.out.printf("%d元存在建设银行%d年零%d天的利息：%f元\n",savedMoney,super.year,day,interest);
 return interest;
 }
}
class BankOfDalian extends Bank{
 double year;
 public double computerInterest(){
  super.year=(int)year;
  double remainNumber=year-(int)year;
  int day=(int)(remainNumber*1000);
  interest=super.computerInterest()+day*0.0002*savedMoney;
  System.out.printf("%d元存在大连银行%d年零%d天的利息是：%f元\n",savedMoney,super.year,day,interest);
  return interest;
 }
}
public class Example5_7{
 public static void main(String args[]){
  int amount=5000;
  ConstructionBank bank1=new ConstructionBank();
  bank1.savedMoney=amount;
  bank1.year=5.216;
  double interest1=bank1.computerInterest();
  BankOfDalian bank2=new BankOfDalian();
  bank2.savedMoney=amount;
  bank2.year=5.216;
  double interest2=bank2.computerInterest();
  System.out.printf("俩个银行利息相差%f元\n",interest2-interest1);
 }
}