Java 小案例+super使用

package com.bytezero.supertest3;

/**
 * 
 * @Description    AccountTest类
 * @author  Bytezero·zhenglei!      Email:420498246@qq.com
 * @version
 * @date 2021年9月20日上午9:52:27
 * @
 *
 */
public class AccountTest
{
    public static void main(String[] args) {
        
        Account acct = new Account(1122,20000,0.045);
        
        acct.withdraw(30000);
        System.out.println("您的账户余额为："+acct.getBalance());
        
        acct.withdraw(2500);
        System.out.println("您的账户余额为："+acct.getBalance());

        acct.deposit(3000);
        System.out.println("您的账户余额为："+acct.getBalance());
        
        System.out.println("月利率为："+(acct.getMonthlyInterest() *100) +"%");
        
        
        
    }
}

package com.bytezero.supertest3;

public class Account
{
    private int id;           //账号
    private double balance;   //余额
    private double annualInterestRate;   //年利率
    
    //构造器
    public Account(int id, double balance, double annualInterestRate) 
    {
        super();
        this.id = id;
        this.balance = balance;
        this.annualInterestRate = annualInterestRate;
    }
    
    //get  set
    
    public int getId()
    {
        return id;
    }
    public void setId(int id)
    {
        this.id = id;
    }

    public double getBalance() 
    {
        return balance;
    }

    public void setBalance(double balance) 
    {
        this.balance = balance;
    }

    public double getAnnualInterestRate() 
    {
        return annualInterestRate;
    }

    public void setAnnualInterestRate(double annualInterestRate) 
    {
        this.annualInterestRate = annualInterestRate;
    }
    
    //返回月利率
    public double getMonthlyInterest()
    {
        return annualInterestRate / 12;
    }
    
    //取钱
    public void withdraw(double amount)
    {
        if(balance >= amount)
        {
            balance -= amount;
            return;
        }
        System.out.println("余额不足！");
    }
    
    
    //存钱
    public void deposit(double amount)
    {
        if(amount > 0)
        {
            balance += amount;
        }
        
        
        
        
        
    }
    
    
    
    
}

 

 

 

package com.bytezero.supertest3;

/**
 * 
 * @Description 
 * @author  Bytezero·zhenglei!      Email:420498246@qq.com
 * @version
 * @date 2021年9月20日上午11:08:11
 * @
 *
 */
public class CheckAccountTest
{
    public static void main(String[] args)
    {
        CheckAccount acct = new CheckAccount(1122,20000,0.045,5000);
        
        acct.withdraw(5000);
        System.out.println("您的账户余额为："+ acct.getBalance());
        System.out.println("您的可透支额度为："+acct.getOverdraft());
        
        acct.withdraw(18000);
        System.out.println("您的账户余额为："+ acct.getBalance());
        System.out.println("您的可透支额度为："+acct.getOverdraft());
        
        acct.withdraw(3000);
        System.out.println("您的账户余额为："+ acct.getBalance());
        System.out.println("您的可透支额度为："+acct.getOverdraft());
        
        
        
        
    }
}

package com.bytezero.supertest3;

/*
 * 
 * 
 */
public class CheckAccount extends Account
{
    private double overdraft; //可透支的限额
    
    
    
    public CheckAccount(int id, double balance, double annualInterestRate,double overdraft)
    {
        super(id, balance, annualInterestRate);
        this.overdraft = overdraft;
    }
    
    
    
    
    public double getOverdraft() {
        return overdraft;
    }




    public void setOverdraft(double overdraft) {
        this.overdraft = overdraft;
    }




    @Override
    public void withdraw(double amount) 
    {
        if(getBalance() >= amount)  //余额足够
        {
            //方式一 
            //setBalance(getBalance() - amount);
            
            //方式二
            super.withdraw(amount);
            //方式三
            //可以将父类的 private double balance;   //余额 改为 
                         //protected double balance
            
            
            
        }
        //余额不够   透支额度 + 余额消费
        else if(overdraft >=( amount - getBalance())) 
        {
            overdraft -= (amount - getBalance());
            
            //setBalance(0);
            //或者
            super.withdraw(getBalance());
            
        }
        else
        {
            System.out.println("超过可透支限额！");
        }
        
    }
    
    
    
    
    

}