我从System.in的输入中得到一个java.util.NoSuchElementException

我正在为一个程序编写代码，该程序显示一个基于x&y坐标的文件以及一个类型值的地图

我的代码正确显示ASCII映射，并允许我在映射上执行函数，但当代码最终返回到switch语句，在该语句中选择下一个选项时，它将跳过“option=input.nextLine（）；”行，并继续执行“input.nextLine（）；”的finally块给我一个Java.util.NoSuchElementException

有人知道这是为什么吗？我知道当枚举中没有这样的元素时，通常会发生这种异常，但我不知道为什么我的代码会跳过input.nextLine（）行，然后在input.nextLine（）上失败

只有在末尾的viewMap开关案例中激活Gorgon案例时，才会发生此错误。我尝试在“input.nextLine（）”调用之前添加“input.nextLine（）”调用，但没有任何区别

其中包括MapViewer程序中Switch语句的代码，以及用于构建和显示地图的代码。最后我还添加了Gorgon类

public class MapViewerMenu {

    public int option = 0;
    public boolean complete = false;

    Scanner input = new Scanner(System.in);

    char [][] mapper = null;

    Map currentMap = null;
    User currentUser = null;
    Vector <Grue> currentGrues = null;

    public void run(){

        while(!complete){
            System.out.println("*******************");
            System.out.println("* Map Viewer Menu *");
            System.out.println("*******************");
            System.out.println("1. Load Files");
            System.out.println("2. Set Symbols");
            System.out.println("3. View Map");
            System.out.println("4. Scramble Map");
            System.out.println("5. Reset Map");
            System.out.println("6. Exit");
            System.out.println("");

            try{
                option = input.nextInt();
            }
            catch(Exception e){
                System.out.println("Error in input.");
                System.out.println("Try again.");
                System.out.println("");
            }
            finally{

// The Error occurs once the program exits viewMap and returns here. 
//It skips the above "option = input.nextInt();" and comes down here and fails.

                input.nextLine();
            }

            switch(option){

            //removed irrelevant cases

            case 3:
                viewMap();
                break;

            case 6:
                complete = true;
                input.close();
                break;

            }
        }
    }

---

一旦它返回到类的原始switch语句，它就会失败，但它应该返回到开头并再次请求输入开关。

通过进入Gorgon的boulder函数，而不是在系统上打开新的扫描仪，修复了错误。在中，我只是在参数中传递了现有的扫描仪

我在system.in上创建了另一个扫描仪并关闭了它，这可能与我的另一个扫描仪的故障有关

---

感谢所有人的帮助和时间。

请创建一个显示您的问题的示例，这是太多的代码。添加了程序运行的概述，我不太熟悉创建SSCCE，因此我希望这对您有所帮助@Keppilt这是我在前面的评论中链接到的文档中的一个分步指南。哪些代码行是

（MapViewer.java:40）

和

（MapViewerMenu.java:92）

指向的。请在代码中添加注释。@peeskillet在错误语句末尾添加了注释。

    public void viewMap(){
        //removed earlier code that built part of the map for readability

        number = currentGrues.elements(); //this is an enumeration

        while(number.hasMoreElements()){
            temp3 = number.nextElement();
            int sure =2;

            switch(temp3.getName()){

            case "Gorgon":

                while(sure != 0){
                    System.out.printf("Would you like the Gorgon to change a square type?\n");
                    System.out.println("(0 for yes, 1 for no.)");

                    try{
                        sure = input.nextInt();
                    }
                    catch(Exception e){
                        System.out.println("Error in input.");
                        System.out.println("Try again.");
                        System.out.println("");
                        sure = 2;
                    }
                    finally{
                        input.nextLine();
                    }

                    if(sure == 0){
                        Gorgon gor = (Gorgon) temp3;
                        gor.boulder(currentMap, mapper);
                        after = true;
                        break;
                    }
                    else{
                        if(sure == 1){
                            break;
                        }
                    }
                }
                break;

// A boolean value after tells the program to reprint the map.

        if(after){
            System.out.println("Since some squares were changed, the updated map is printed.");
            System.out.println("");
            System.out.printf("Map Name: %s", currentMap.getName());
            System.out.println("");

            for(xpos = 0, ypos = 0; xpos < 16 && ypos < 16;){
                System.out.print(mapper[xpos][ypos]);
                xpos++;

                if(xpos < 16){
                    continue;
                }
                else{
                    System.out.println("");
                    ypos++;
                    if(ypos < 16){
                        xpos = 0;
                        continue;
                    }
                }
            }
            System.out.println("");
        }
}

//This should then go back to the "option = input.nextInt" line, where it should ask the user for input, but doesnt.

import java.util.Scanner;

public class Gorgon extends Giant {

     //Included is the function called by the viewMap switch statement.
     //I added this because the error might exist here.
     //other classes have similar functions, but perform just fine.

    public void boulder(Map map, char[][] mapper){
        int x = 0;
        int y = 0;
        Scanner input = new Scanner(System.in);

        System.out.println("The Gorgon wants to turn an adjacent Square to stone!");
        System.out.printf("Its position is (%d,%d).\n", this.currPos.col, this.currPos.row);

        do{
            do{ // Get an adjacent x coordinate
                try{
                    System.out.println("Enter an x coordinate:");
                    x = input.nextInt();
                }
                catch(Exception e){
                    System.out.println("Error in input.");
                    System.out.println("Try again:");
                    System.out.println("");
                }
                finally{
                    input.nextLine();
                }
            }while(!(x >= currPos.col-1 && x <= currPos.col+1));

            do{  // get an adjacent y coordinate
                try{
                    System.out.println("Enter a y coordinate:");
                    y = input.nextInt();
                }
                catch(Exception e){
                    System.out.println("Error in input.");
                    System.out.println("Try again:");
                    System.out.println("");
                }
                finally{
                    input.nextLine();
                }
            }while(!(y >= currPos.row-1 && y <= currPos.row+1)); // keep asking for input while the input isn't within range.

        }while(!((x >= currPos.col-1 && x <= currPos.col+1) && (y >= currPos.row-1 && y <= currPos.row+1)));

        mapper[x][y] = 'B'; //Change the value in map data.
        input.close();  //Close local input reader.

Exception in thread "main" java.util.NoSuchElementException: No line found
    at java.util.Scanner.nextLine(Unknown Source)
    at viewer.MapViewerMenu.run(MapViewerMenu.java:92) //points to the finally block at the beginning, where "input.nextLine()" is written.
    at viewer.MapViewer.main(MapViewer.java:40) //This is just the original main that runs the program.