刚才跟着尚硅谷的宋老师学了两个小例题，首先是第一个例题，第一个例题难度不大，主要是考察了封装性，逻辑还是比较清晰的。
Account类：
package OOPexer1;
public class Account
{
private int id;
private double balance;
private double annualInterestRate;
public Account(int id, double balance, double annualInterestRate) {
this.id = id;
this.balance = balance;
this.annualInterestRate = annualInterestRate;
}
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;
}
//取钱
public void withdraw(double amount)
{
if(balance0)
{
balance+=amount;
System.out.println("成功存入"+amount);
}
}
}
Customer类：
package OOPexer1;
public class Customer {
private String firstName;
private String lastName;
private Account account;
public Customer(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
public String getFirstName() {
return firstName;
}
public String getLastName() {
return lastName;
}
public Account getAccount() {
return account;
}
public void setAccount(Account account) {
this.account = account;
}
}
测试类：
package OOPexer1;
public class CustomerTest
{
public static void main(String[] args) {
Customer cust=new Customer("Jane","Smith");
Account acct=new Account(1000, 2000, 0.0123);
cust.setAccount(acct);//客户的account由初始化的null赋值为acct的地址，指向定义的账户对象
cust.getAccount().deposit(100);
cust.getAccount().withdraw(960);
cust.getAccount().withdraw(2000);
}
}
输出结果：
成功存入100.0
成功取出960.0
余额不足，取款失败
第二个例子就有一点点小难度了，主要是因为用到了对象数组，对象数组在使用之前也需要提前声明开辟好空间。先把代码展示出来：
Account类：
package OOPexer2;
public class Account {
private double balance;
public Account(double init_balance)
{
this.balance=init_balance;
}
public double getBalance()
{
return this.balance;
}
//存钱
public void deposit(double amt)
{
if(amt>0)
{
balance+=amt;
System.out.println("存钱成功");
}
}
//取钱
public void withdraw(double amt)
{
if(balance>=amt)
{
balance-=amt;
System.out.println("取钱成功");
}else
{
System.out.println("余额不足");
}
}
}
Bank类：
package OOPexer2;
public class Bank {
private Customer[] customer;//或者可以在这 private Customer[] customer=new Customer[10];
//可以用来存放多个客户的数组
private int numberOfCustomers;//记录客户个数
public Bank()
{
customer=new Customer[10];//数组要指定长度
}
//添加客户
public void addCustomer(String f,String l)
{
Customer cust=new Customer(f,l);
// customer[numberOfCustomers]=cust;
// numberOfCustomers++;
//或
customer[numberOfCustomers++]=cust;
}
//获取客户个数
public int getNumberOfCustomer()
{
return numberOfCustomers;
}
//获取指定位置上的客户
public Customer getCustomer(int index)
{
// return customer[index];这样写不太好
if(index>=0&&index
Customer类：
package OOPexer2;
public class Customer {
private String firstName;
private String lastName;
private Account account;
public Customer(String l,String f)
{
this.firstName=f;
this.lastName=l;
}
public String getFirstName()
{
return this.firstName;
}
public String getLastName()
{
return this.lastName;
}
public Account getAccount()
{
return this.account;
}
public void setAccount(Account account)
{
this.account=account;
}
}
测试类：
package OOPexer2;
public class BankTest
{
public static void main(String[] args) {
Bank bank=new Bank();
bank.addCustomer("Jane", "Smith");
System.out.println("当前账户人数为："+bank.getNumberOfCustomer());
//System.out.println(bank.getCustomer(0));
//连续操作
bank.getCustomer(0).setAccount(new Account(2000));
bank.getCustomer(0).getAccount().withdraw(500);
double balance =bank.getCustomer(0).getAccount().getBalance();
System.out.println("账户余额为"+balance);
bank.addCustomer("Tom", "Smith");
System.out.println("当前账户人数为："+bank.getNumberOfCustomer());
}
}
首先明确一下其中的类 ：银行类 、客户类、账户类。
在一个例子中银行对象一般只有一个，银行中有客户类，而此例中将客户类放在了数组中，方便对客户的增删改查，一个客户对象可能有多个账户对象 。所以整体上这三个类是逐个包含的关系。在内存中是逐个存储下一个的地址，指向下一个对象 。
