Question

目前我正在编写一个介绍Java类的程序。我的谜题有两件。希望这是一个相对简单的回答问题。

首先，这是我尝试用作主程序的内容：

import java.util.Scanner;

public class TheATMGame
{
 public static void main(String[] args){


    Scanner input = new Scanner(System.in);


    double newBalance = 0;
    double monthlyInterest = 0;
    int answer = 0;


    int i=1;
    while (i < 100) {
        System.out.print ("Please enter your ID: ");
        answer = input.nextInt();
        System.out.println(" ");
        if (answer >=0 && answer<10) 
        TheATMGame.runGame (answer);
        else
         System.out.println("Sorry, this ID is invalid.");
     }
    }


    public static void runGame(int id) {
      double amount = 0;
      int continueOn = 0;
      while (continueOn < 4) {
        ATMGame myATM = new ATMGame();
        Scanner input = new Scanner(System.in);
        System.out.println ("---Main menu--- ");
        System.out.println ("1: Check balance ");
        System.out.println ("2: Withdraw ");
        System.out.println ("3: Deposit ");
        System.out.println ("4: exit ");

        int answer = input.nextInt();

        if (answer == 1)
            System.out.println("your balance is: " + myATM.getBalance (id));
        else if (answer == 2){
            System.out.println("Enter an amount to withdraw: ");
            amount = input.nextInt();
            myATM.withdraw(amount, id);
        }
        else if (answer == 3)
{
            System.out.println("Enter an amount to deposit: ");
            amount = input.nextInt();
            myATM.deposit(amount, id);
        }
        else if (answer == 4)
            continueOn = 4;
        else if (answer > 4)
            System.out.println ("Please review the main menu. " +
                    "Your selection must be between 1-4.");
      }
    }

//ATM class (balance, annualInterestRate2, id2)
//ATM myATM = new ATM (20000, 4.5, 1122 );
//newBalance = myATM.withdraw(2500);
//newBalance = myATM.deposit(3000);
//monthlyInterest = myATM.getMonthlyInterestRate();
//System.out.println("Your current balance is: " + newBalance);
//System.out.println ("Your monthly interest rate is: " +  monthlyInterest);



}

现在这里是我想要加入该计划的所有课程：

import java.util.Date;

public class ATMGame  {

    private double annualInterestRate = 0;
    private double balance = 0;
    private int id = 11;
    private int[] ids = {0,1,2,3,4,5,6,7,8,9};
    private int[] balances = {100,100,100,100,100,100,100,100,100,100};
    public Date dateCreated;


    public ATMGame() {

    }
    public ATMGame (double balance2, double annualInterestRate2, int id2) {
        balance = balance2;
        annualInterestRate = annualInterestRate2;
        id = id2;
        dateCreated.getTime();
    }


    public double getMonthlyInterestRate() {
        double monthlyInterest = annualInterestRate/12;
        return monthlyInterest;
    }


    public double withdraw(double amountWithdrawn, int id) { //This method withdraws money from the account

        double newBalance = balances[id] - amountWithdrawn;
        System.out.println("Your withdrawel has processed. New balance: " + newBalance);
        balances[id] = (int) newBalance;
        return newBalance ;

    }


    public double deposit(double amountDeposited, int id) { //This method deposits money in the account
        double newBalance = balances[id] + amountDeposited;
        System.out.println("Your deposit has processed. New Balance is: " + newBalance);
        balances[id] = (int) newBalance;
        return newBalance ;

    }

    public double getBalance(int id) {
        double myBalance = balances[id];
        balance = myBalance;
        return myBalance ;
    }


}

当我尝试运行第一个程序时，它会显示“找不到主要类”。正如你所看到的那样，我已经写了“public void Main（）...”这一行来处理这个问题，但是天真地说它不起作用。我做错了什么？

替换“public void Main（）{”with“public static void main（String [] args）{”仍然返回错误：“找不到主类。”：/

http://img21.imageshack.us/img21/9016/asdfsdfasdfg.jpg

我能够通过将Main.java更改为TheATMGame.java然后从ATMGame.java运行来修复它。

Answer 1

您应该使用：

public static void main(String[] args)

而不是Main，因为JVM首先调用此方法。这是一个惯例。

Answer 2

你刚刚错误定义了主要内容。应该是：

public static void main(String[] args) {
    ....
}

但是，您的代码会遇到其他一些问题。快速浏览......

你的main（）是一个函数，以及runGame（） - 一个不应该在另一个中定义。
你不能将你的两个类命名为同一个东西 - 调用main（）类与ATMGame不同。
不确定ATM class (balance, annualInterestRate2, id2)的用途，但它不是有效的Java。

Answer 3

您的方法签名必须是：

public static void main(String[] args) {
 ...
}

这是你必须遵循的惯例。其他任何东西都行不通。

Answer 4

在您的班级ATMGame中，替换以下内容：

public void Main() {

使用：

public static void main(String[] args) {

此外，由于此方法必须是静态的，因此您需要更改以下内容：

if (answer >=0 && answer<10)
     runGame (answer);
 else

使用：

if (answer >=0 && answer<10)
     ATMGame.runGame (answer);
 else

最后，您需要将rungame的方法签名更改为静态。改变它：

public void runGame(int id) {

为：

public static void runGame(int id) {

Answer 5

公共类的名称应与文件名匹配。屏幕截图中的情况并非如此。还要确保所有内容都正确编译然后重试（使用public static void main（String [] args）{...}方法。）

Java方法和类，它们如何组合在一起？

5 个答案: