Java ATM 程序只是在 ATM 处打印。(init)(ATM.java :6) but compiles with no errors (not using any arrays in program)

Question

我正在制作一个 ATM 程序来学习 java，使用 cmd 来编译和运行它。该程序编译没有错误，但在运行时仅打印 at ATM.(init)(ATM.java:6)。

如有任何帮助，我们将不胜感激!

public class ATM
{
    Toolbox myToolbox = new Toolbox();
    Integer balance;
    ATM myATM = new ATM();

    public static void main(String[] arg)
    {
        ATM myATM = new ATM();
        myATM.go();
        myATM.printBal();
        myATM.mainMenu();
    }

    public void go()
    {
        System.out.println("Welcome to online ATM banking");
        System.out.println("How much do you want in your account?");
        //System.out.println("Enter your number");      
        balance = myToolbox.readIntegerFromCmd();
    }   

    public void printBal()
    {
        System.out.println("****************************************");
        System.out.println(balance);
        System.out.println("****************************************");
    }

    public void mainMenu()
    {
        Integer selected;
        System.out.println("What do you want to do?");
        System.out.println("1 : Withdraw");
        System.out.println("2 : Deposit");
        System.out.println("3 : Inquire");
        System.out.println("4 : Quit");
        System.out.println("Enter your number");
        selected = myToolbox.readIntegerFromCmd();
        //{ if statement for mainMenu options
        if(selected.equals(1))
        {
            myATM.withdraw();
        }
        else if(selected.equals(2))
        {
            myATM.deposit();
        }
        else if(selected.equals(3))
        {
            myATM.inquire();
        }
        else if(selected.equals(4))
        {
            myATM.quit();
        }
        //} if statement end 
    }
    //{ mainMenu methods
    public void withdraw()
    {
        System.out.println("****************************************");
        System.out.println("Withdraw");
        System.out.println("****************************************");
        Integer takeOut;
        System.out.println("How much do you want to withdraw?");
        takeOut= myToolbox.readIntegerFromCmd();
        balance = balance - takeOut;
        myATM.printBal();
        myATM.mainMenu();
    }

    public void deposit()
    {
        System.out.println("****************************************");
        System.out.println("Deposit");
        System.out.println("****************************************");
        Integer putIn;
        System.out.println("How much do you want to deposit?");
        putIn = myToolbox.readIntegerFromCmd();
        balance = balance + putIn;
        myATM.printBal();
        myATM.mainMenu();
    }

    public void inquire()
    {
        System.out.println("****************************************");
        System.out.println("Inquire");
        System.out.println("****************************************");
        //why am I making a method that is already written
        myATM.printBal();
        myATM.mainMenu();
    }

    public void quit()
    {
        System.out.println("****************************************");
        System.out.println("Thanks for using the fail ATM");
        System.out.println("****************************************");
        System.out.println(balance);
        System.out.println("****************************************");
        System.out.println("Goodbye");
        System.out.println("****************************************");
        System.exit(0);
    }
    //}
}

Answer 1

无论如何，问题可能出在 main 方法之前的第 4 行(我认为)。

ATM myATM = new ATM(); 

这是在每个 ATM 实例中实例化一个 ATM 并导致它们无限循环，最终将抛出 StackOverflowException。但这将是一个很长的路要走。

将相应的行替换为:

private static ATM myATM;

public static void main(String[] arg)
{
    myATM = new ATM();