Java中对象数组的习题练习

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 *** 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 。
					
										


					

						
欢迎分享，转载请注明来源：内存溢出
原文地址: http://outofmemory.cn/zaji/5672306.html