1实现个人银行管理系统c++转Java代码，来熟悉Java的语法知识，掌握Java的语法知识 2.逐步完善个人银行管理系统的功能， 根据系统的逐步演化，体会面对对象的思想，Java的特性。
一.个人银行管理系统0.1
1.Java里面没有c++ 里的namespace，而是换成了package。
2.private,public等在Java里面需要单独写在每一个成员前面。
3.Java里不允许普通函数（除抽象类，接口等）的声明与函数体分开，要写一起。
4.c++ 里面void test (int _x) const{}时const指该函数不能修改类的成员，而Java 里面final void
5.test(){}时final表示该函数不能被重写。Java里没有const。
6.Java里的输出是语句是System.out.println(变量名 + “字符串”)；相当于“<<”改成了“+”。
7.Java里是不用写什么math.h等头文件的，类库里都有。比如取整：Math.floor() 。
8.c++ 里面建立类的对象可以直接：类名 对象名（参数），而Java里面需要：类名 对象名 = new 类名（参数）
package blank_system;
public class SavingAccount {
private int id; //账号
private double balance; //余额
private double rate; //存款的年利率
private int lastDate; //上次变更余额的时期
private double accumulation; //余额按日累加之和
//记录一笔帐，date为日期，amount为金额，desc为说明
void record(int date, double amount) {
accumulation = accumulate(date);
lastDate = date;
amount = floor(amount * 100 + 0.5) / 100; //保留小数点后两位
balance += amount;
System.out.println(date+"\t"+id+","+amount+'\t'+balance);
}
//获得到指定日期为止的存款金额按日累积值
double accumulate(int date){
return accumulation + balance * (date - lastDate);
}
//构造函数
public SavingAccount(int date, int id, double rate){
this.id=id;
this.balance=0;
this.rate=rate;
this.lastDate=date;
this.accumulation=0;
System.out.println(date+" #"+id+" is created");
}
int getId() { return id; }
double getBalance() { return balance; }
double getRate() { return rate; }
//存入现金
void deposit(int date, double amount) {
record(date, amount);
}
//取出现金
void withdraw(int date, double amount) {
if (amount > getBalance()) {
System.out.println("Error: not enough money");
}
else {
record(date, -amount);}
}
//结算利息，每年1月1日调用一次该函数
void settle(int date) {
double rate=getRate();
double interest = (accumulate(date)*rate) /365; //计算年息
if (interest != 0) {
record(date, interest);
}
accumulation = 0;
}
//显示账户信息
void show() {
System.out.println("#"+id+" Balance "+balance);
}
public static void main(String args[]) {
//建立几个账户
SavingAccount sa0=new SavingAccount(1, 21325302, 0.015);
SavingAccount sa1=new SavingAccount(1, 58320212, 0.015);
//几笔账目
sa0.deposit(5, 5000);
sa1.deposit(25, 10000);
sa0.deposit(45, 5500);
sa1.withdraw(60, 4000);
//开户后第90天到了银行的计息日，结算所有账户的年息
sa0.settle(90);
sa1.settle(90);
//输出各个账户信息
sa0.show();System.out.println("\n");
sa1.show();System.out.println("\n");
}
};
个人银行账户管理系统0.2
1.Java调用函数的时候通过要操作的对象或者通过类名调用函数 2.在使用函数的时候要注意函数作用于的问题
import static java.lang.Math.*;
public class SavingsAccount {
private int id; //账号
private double balance; //余额
private double rate; //存款的年利率
private int lastDate; //上次变更余额的时期
private double accumulation; //余额按日累加之和
private static double total; //所有账户的总金额
//记录一笔帐，date为日期，amount为金额，desc为说明
void record(int date, double amount) {
accumulation = accumulate(date);
lastDate = date;
amount = floor(amount * 100 + 0.5) / 100; //保留小数点后两位
balance += amount;
total += amount;
System.out.println(date+"# "+id+"\t"+amount+"\t"+balance);
}
//获得到指定日期为止的存款金额按日累积值
double accumulate(int date){
return accumulation + balance * (date - lastDate);
}
//构造函数
public SavingsAccount(int date, int id, double rate) {
this.lastDate=date;
this.id=id;
this.balance=0;
this.rate=rate;
this.accumulation=0;
System.out.println(date+"\t#"+id+" is created");
}
int getId() { return id; }
double getBalance() { return balance; }
double getRate() { return rate; }
static double getTotal() { return total; }
//存入现金
void deposit(int date, double amount) {
record(date, amount);
}
//取出现金
void withdraw(int date, double amount) {
if (amount > getBalance())
System.out.println("Error: not enough money");
else
record(date, -amount);
}
//结算利息，每年1月1日调用一次该函数
void settle(int date) {
double interest = accumulate(date) * rate / 365; //计算年息
if (interest != 0)
record(date, interest);
accumulation = 0;
}
//显示账户信息
void show() {
System.out.println("#"+id+"\tBalance: "+balance);
}
public static void main(String args[]) {
SavingsAccount sa0=new SavingsAccount(1, 21325302, 0.015);
SavingsAccount sa1=new SavingsAccount(1, 58320212, 0.015);
//几笔账目
sa0.deposit(5, 5000);
sa1.deposit(25, 10000);
sa0.deposit(45, 5500);
sa1.withdraw(60, 4000);
//开户后第90天到了银行的计息日，结算所有账户的年息
sa0.settle(90);
sa1.settle(90);
//输出各个账户信息
sa0.show(); System.out.println("\n");
sa1.show(); System.out.println("\n");
System.out.println("Total: "+getTotal());
}
}
三.个人银行管理系统0.3 1.Java中创建对象是通过new关键字创建，而C++中的&语法不能使用； 2.println的输出方式 3.System.exit（-1）退出 4.完善账户的存储功能
//date.cpp
public class Date {
//存储平年中某个月1日之前有多少天，为便于getMaxDay函数的实现，该数组多出一项
final int DAYS_BEFORE_MONTH[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };
private int year; //年
private int month; //月
private int day; //日
private int totalDays; //该日期是从公元元年1月1日开始的第几天
boolean isLeapYear() { //判断当年是否为闰年
return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
}
public Date(int year, int month, int day) //用年、月、日构造日期
{
this.day = day;
this.month = month;
this.year = year;
if (day <= 0 || day > getMaxDay()) {
System.out.println("Invalid date: ");
show();
System.out.println();
System.exit(1);
}
int years = year - 1;
totalDays = years * 365 + years / 4 - years / 100 + years / 400 + DAYS_BEFORE_MONTH[month - 1] + day;
if (isLeapYear() && month > 2) totalDays++;
}
public int getYear() { return year; }
public int getMonth() { return month; }
public int getDay() { return day; }
public int getMaxDay() //获得当月有多少天
{
if (isLeapYear() && month == 2)
return 29;
else
return DAYS_BEFORE_MONTH[month]- DAYS_BEFORE_MONTH[month - 1];
}
public void show() //输出当前日期
{
System.out.print(getYear() + "-" + getMonth() + "-" + getDay());
}
//计算两个日期之间差多少天
int distance(Date date)
{
return totalDays - date.totalDays;
}
}
public class SavingsAccount {
private String id; //帐号
private double balance; //余额
private double rate; //存款的年利率
private Date lastDate; //上次变更余额的时期
private double accumulation; //余额按日累加之和
private static double total = 0; //所有账户的总金额
//记录一笔帐，date为日期，amount为金额，desc为说明
private void record(Date date, double amount, String desc)
{
accumulation = accumulate(date);
lastDate = date;
amount = Math.floor(amount * 100 + 0.5) / 100; //保留小数点后两位
balance += amount;
total += amount;
date.show();
System.out.println("\t#" + id + "\t" + amount + "\t" + balance + "\t" + desc);
}
//报告错误信息
private void error(String msg)
{
System.out.println("Error(#" + id + "): " + msg);
}
//获得到指定日期为止的存款金额按日累积值
private double accumulate(Date date)
{
return accumulation + balance * date.distance(lastDate);
}
//构造函数
public SavingsAccount(Date date,String id, double rate)
{
this.id = id;
this.balance = 0;
this.rate = rate;
this.lastDate = date;
this.accumulation = 0;
date.show();
System.out.println( "\t#" + id + " created");
}
public String getId() { return id; }
public double getBalance() { return balance; }
public double getRate() { return rate; }
public static double getTotal() { return total; }
//存入现金
public void deposit(Date date, double amount, String desc)
{
record(date, amount, desc);
}
//取出现金
public void withdraw(Date date, double amount, String desc)
{
if (amount > getBalance())
error("not enough money");
else
record(date, -amount, desc);
}
//结算利息，每年1月1日调用一次该函数
public void settle(Date date)//计算年息
{
double interest = accumulate(date) * rate / date.distance(new Date(date.getYear() - 1, 1, 1));
if (interest != 0)
record(date, interest, "interest");
accumulation = 0;
}
//显示账户信息
public void show()
{
System.out.println(id + "\tBalance: " + balance);
}
}
//6_25.cpp
public class PersonalBank {
public static void main(String[] args) {
//Date date = new Date(2008, 11, 1); //起始日期
/*
//建立几个账户
SavingsAccount accounts[] = {
new SavingsAccount(date, "S3755217", 0.015),
new SavingsAccount(date, "02342342", 0.015)
};
int n = accounts.length; //账户总数
//11月份的几笔账目
accounts[0].deposit(new Date(2008, 11, 5), 5000, "salary");
accounts[1].deposit(new Date(2008, 11, 25), 10000, "sell stock 0323");
//12月份的几笔账目
accounts[0].deposit(new Date(2008, 12, 5), 5500, "salary");
accounts[1].withdraw(new Date(2008, 12, 20), 20000, "buy a laptop");
//结算所有账户并输出各个账户信息
System.out.println();
for (int i = 0; i < n; i++) {
accounts[i].settle(new Date(2009, 1, 1));
accounts[i].show();
//System.out.println();
}
System.out.println("Total: " + SavingsAccount.getTotal());
*/
Date date1 = new Date(2008, 11, 50);
//Date date2 = new Date(2009, 2, 1);
date1.show();
//System.out.println();
//System.out.println(date1.getMaxDay());
//System.out.println();
//date2.show();
//System.out.println();
//System.out.println(date2.getMaxDay());
//System.out.println();
//System.out.println(date2.distance(date1));
}
}
以上就是简单的语法变更，对比C++与Java的不同，熟悉Java的语法知识。
