Java实现ATM机

Java作业ATM机，使用单例模式，实现存取款，查询余额

import javax.swing.JOptionPane;
public class Main {
	public static mian(String[]args){
		ATM.getInstance(10);//初始化包含十个账户的ATM
		userName=JOptionPane.showInputDialog("用户名");//ÀûÓöԻ°¿òÊäÈëÓû§Ãû
		passWord=JOptionPane.showInputDialog("密码");//ÀûÓöԻ°¿òÊäÈëÃÜÂë
		
	}
}
class ATM{
	public static ATM instance;
	private double deposits[];
	private String userNames[];
	private String passwords[];
	private int currentId;//当前登陆的账户id
	private int accounts=0;//当前ATM机中的账户数量
	final double NON_EXISTENT=-1;
	private ATM(int MaxAccounts){
		deposits=new double[MaxAccounts];
		userNames=new String[MaxAccounts];
		passwords=new String[MaxAccounts];
		currentId=-1;
	}
	public boolean RegisterAnAccount(String acconut,String password){
		if (accounts==userNames.length) {
			//System.out.println("注册失败");
			return false;
		} else{
			userNames[accounts]=acconut;
			passwordS[acconuts]=password;
			return true;
		}
	}
	public double GetAccountBalance(String Name,String passWord) {	//获取账户余额
		if (currentId!=-1) {
			return deposits[currentId];
		}
		System.out.println("该账户不存在");
		return 0;
	}
	public boolean Withdraw(double money){//取钱
		if (currentId==-1 && money>deposits[currentId]) {
			return false;
		}else{
			deposits[currentId]-=money;
			return true;
		}
	}
	public boolean Deposit(double money){//存钱
		if (currentId!=NON_EXISTENT) {
			deposits[currentId]+=money;
			return true;
		}else{
			return false;
		}
	}
	private int FindAccount(String Name) {//查找是否存在该账户
		for(int id=0;id