JAVA继承练习——重写父类方法与super关键字之银行利息编程例题

//bank.java--父类
public class bank{
int savedMoney;
int year;
double interest;
double interestRate=0.29;
public double computerInterest(){
interest=year*interestRate*savedMoney;
return interest;
}
public void setInterestRate(double rate){
interestRate=rate;
}
}

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"bank.java" 14L, 246C

//construction.java
public class constructionBank extends bank{
double year;
public double computerInterest(){
super.year=(int)year;
double r=year-(int)year;
int day=(int)(r*1000);
double yearInterest=super.computerInterest();
double dayInterest=day*0.0001*savedMoney;
interest=yearInterest+dayInterest;
System.out.printf("建设银行存款利息为：%f\n",interest);
return interest;
}
}


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"constructionBank.java" 15L, 367C

//guangzhouBank.java
public class guangzhouBank extends bank{
double year;
public double computerInterest(){
super.year=(int)year;//调用父类变量year并赋值，如果这里不调用并赋值，下面调用父类方法computerInterest()时>因为利用的是父类中的变量year，计算返回得到的yearInterest的值将是0，因为year系统默认赋值0.
double r=year-(int)year;
int day=(int)(r*1000);
double yearInterest=super.computerInterest();
double dayInterest=day*0.00012*savedMoney;
interest=yearInterest+dayInterest;
System.out.printf("广州银行存款利息为：%f\n",interest);
return interest;
}
}

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"guangzhouBank.java" 14L, 606C

//saveMoneyMain.java
import java.util.Scanner;
public class saveMoneyMain{
public static void main(String args[]){
Scanner sc=new Scanner(System.in);
constructionBank bank1=new constructionBank();
guangzhouBank bank2=new guangzhouBank();
System.out.println("请输入存款金额：");
bank1.savedMoney=bank2.savedMoney=sc.nextInt();
System.out.println("请输入存款年限：");
bank1.year=bank2.year=sc.nextDouble();
bank1.setInterestRate(0.035);
bank2.setInterestRate(0.035);
double interest1=bank1.computerInterest();
double interest2=bank2.computerInterest();
System.out.printf("两银行相差利息金额为：%f\n",interest2-interest1);
}
}

结果：

请输入存款金额：
8000
请输入存款年限：
8.236
建设银行存款利息为：2428.800000
广州银行存款利息为：2466.560000
两银行相差利息金额为：37.760000