类和对象1

创建一个简单版本的银行 Account 类

创建一个简单版本的 Account 类。将这个源文件放入 banking 程序包中。在创建单个帐户的默认程序包中，编写一个测试程序 TestBanking。这个测试程序初始化帐户余额，并可执行几种简单的事务处理。最后，该测试程 序显示该帐户的最终余额

package banking;

// 在 banking 包下创建 Account 类
public class Account {
    private double balance;
    
//带有一个参数（init_balance）的公有构造器
public Account(double init_balance){
    System.out.println("Creating an account with a "+init_balance+" balance");
    balance=init_balance;
}

//该方法用于获取余额
public double geBalance(){
    return balance;
}

//该方法向当前余额增加金额
public void deposit(double amt){
    System.out.println("deposit "+amt);
    balance=balance+amt;
}

//从当前余额中减去金额
public void withdraw(double amt){
    System.out.println("deposit "+amt);
    balance=balance-amt;
}

}

package test;

import banking.Account;

public class TestBanking {

    public static void main(String[] args) {
        Account p1= new Account(500);
        p1.withdraw(150);
        p1.deposit(22.5);
        p1.withdraw(47.62);
        System.out.println("The account has a balance of "+p1.geBalance());

    }

}

圆柱体的底面积和高

import java.util.Scanner;

public class Test {

    public static void main(String[] args) {
        float R,H;
        Scanner reader = new Scanner(System.in);
        Column Column=new Column();
        System.out.println("plaese input R:");
        R=reader.nextFloat();
        System.out.println("plaese input H:");
        H=reader.nextFloat();
        Column.S(R);
        Column.V(R, H);

    }

}

public class Column {

    double pi=java.lang.Math.PI;
    
    public double S(float R) {
        
        System.out.println("s="+pi*R*R);
        return pi*R*R;
        

    }
    
    public double V(float R,float H) {
        
        System.out.println("v="+pi*R*R*H);
        return pi*R*R*H;    

    }

    
}