Java 使用扫描仪时出现NoTouchElement异常

我试图在程序中使用

Scanner

s第二次从控制台获取输入，但在另一种方法中调用第二次

Scanner

时，它出现了NoTouchElement异常

    public class Garden {
    public static final Garden GARDEN = new Garden();
    //variable declartaions removed
    public static void main(String[] args) {
        if (null != args && 0 < args.length) {
            GARDEN.fileName = args[0].trim();
        }
        if (GARDEN.fileName != null) {
            GARDEN.fileReader(GARDEN.fileName);
        } else {
            GARDEN.fileReader();
        }

        GARDEN.startMenu();
        int mainI = 0;
        while (mainI != 1000000) {
            try {
                Thread.sleep(0);
            } catch (InterruptedException e) {
            }
            GARDEN.daysWeather();
            GARDEN.anotherDay();
            mainI++;
        }
    }


    protected void fileReader() { // asks for file name for config file
        System.out.println("Enter File Name Please");
        Scanner cmdReader = null;
        String cmdInput = null;
        try {
            cmdReader = new Scanner(System.in);
            cmdInput = cmdReader.nextLine();
        } catch (NoSuchElementException noSuchElement) {
            noSuchElement.printStackTrace();
            fileReader();  //throwing error here
        }

        //code removed
    }



    protected void startMenu() {// modified code from ATM lab (week2)
    int selected = 0;
        //code removed 
        Scanner climateScanner = new Scanner(System.in);
        System.out.println("Select a number 1-4");
        selected = climateScanner.nextInt();
        switch (selected) {
        case 1: // semiarid
            weatherType = 10; //10% chance to rain
            climateScanner.close();
            break;
        case 2: // arid
            weatherType = 20; //5% chance to rain
            climateScanner.close();
            break;
        case 3:
            weatherType = 50; //2% chance to rain
            tropicalWeather = true;
            climateScanner.close(); 
            break;
        case 4:
            weatherType = 20;//5% chance to rain 
            storming = true;
            climateScanner.close();
            break;
        default:
            System.out.println("Invalid Input try again");
            startMenu(); //using Recursion to ask for input again
            break;
        }
        //code removed
    }
}

如果我从运行

fileReader（）

时删除

startMenu（）

，它会工作，但是由于某种原因，在运行后会抛出异常

    public class Garden {
    public static final Garden GARDEN = new Garden();
    //variable declartaions removed
    public static void main(String[] args) {
        if (null != args && 0 < args.length) {
            GARDEN.fileName = args[0].trim();
        }
        if (GARDEN.fileName != null) {
            GARDEN.fileReader(GARDEN.fileName);
        } else {
            GARDEN.fileReader();
        }

        GARDEN.startMenu();
        int mainI = 0;
        while (mainI != 1000000) {
            try {
                Thread.sleep(0);
            } catch (InterruptedException e) {
            }
            GARDEN.daysWeather();
            GARDEN.anotherDay();
            mainI++;
        }
    }


    protected void fileReader() { // asks for file name for config file
        System.out.println("Enter File Name Please");
        Scanner cmdReader = null;
        String cmdInput = null;
        try {
            cmdReader = new Scanner(System.in);
            cmdInput = cmdReader.nextLine();
        } catch (NoSuchElementException noSuchElement) {
            noSuchElement.printStackTrace();
            fileReader();  //throwing error here
        }

        //code removed
    }



    protected void startMenu() {// modified code from ATM lab (week2)
    int selected = 0;
        //code removed 
        Scanner climateScanner = new Scanner(System.in);
        System.out.println("Select a number 1-4");
        selected = climateScanner.nextInt();
        switch (selected) {
        case 1: // semiarid
            weatherType = 10; //10% chance to rain
            climateScanner.close();
            break;
        case 2: // arid
            weatherType = 20; //5% chance to rain
            climateScanner.close();
            break;
        case 3:
            weatherType = 50; //2% chance to rain
            tropicalWeather = true;
            climateScanner.close(); 
            break;
        case 4:
            weatherType = 20;//5% chance to rain 
            storming = true;
            climateScanner.close();
            break;
        default:
            System.out.println("Invalid Input try again");
            startMenu(); //using Recursion to ask for input again
            break;
        }
        //code removed
    }
}

公共类花园{
公共静态最终花园=新花园（）；
//取消可变申报单
公共静态void main（字符串[]args）{
if（null！=args&&0

你不能用这种方式访问它。您必须初始化该类或使您的方法成为静态的。还有什么是花园

好的，现在您已经编辑了代码

再次

---

问题是两个不同的扫描器（一个在startMenu（）中，一个在readFile（）中）更改了它，所以类变量中有一个Scanner Scanner=new Scanner（System.in），然后从方法中调用Scanner.nextLine（），或者使

startMenu

静态。fileReader（GARDEN.fileName）只是fileReader（）的另一个实例在控制台中启动程序时，java Garden testA.txt将运行fileReader（文件名）java Garden将运行fileReader（）两个fileReader（）之间的差异方法是，获取参数的方法从参数获取文件名，而不带参数的方法通过扫描仪从控制台输入获取文件名（不确定这是否是您的意思，我是否有另一个同名方法）@user1642671我建议您使用

调试程序

。然后，您将很容易意识到我尝试过的问题：它获取cmdReader=new Scanner（System.in）；然后抛出异常是否每次使用后都与System.in有关？GARDEN是创建的单例吗？我不认为这是问题所在，因为它在未调用GARDEN.startMenu（）时与GARDEN.fileReader（）一起工作

 GARDEN.fileReader(GARDEN.fileName); // you are parsing input argument 
                                // But method in your class is no argument method