扫描仪输入异常

Question

代码 在接受输入时运行后抛出这些异常 第一个输入正常工作，但第二个输入抛出异常

sample output should be like this

program output

Exception in thread "main" java.util.NoSuchElementException
        at java.util.Scanner.throwFor(Scanner.java:862)
        at java.util.Scanner.next(Scanner.java:1371)
        at WeatherEngine.WeatherRecord(WeatherEngine.java:53)
        at WeatherProcessingSystem.main(WeatherProcessingSystem.java:36)
    WARNING: process exited with a(n) Unknown (1) error code

主要方法

public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int choice=0;
    boolean flag = true;
    WeatherEngine weather = new WeatherEngine();
    System.out.println("Welcome to Weather Data Processing System!"
            +"\nYou can process weather information using this system.\n"
            +"\nPlease select a feature you wish to use from the following:\n");
    do{
        System.out.println("1. \t Weather Record"
                +"\n2. \t Averages"
                +"\n3. \t Maximums"
                +"\n4. \t Minimums"
                +"\n5. \t Total Precipitation"
                +"\n6. \t Extremes"
                +"\n0. \t Quit");
        do{
            try{
                flag=false;
                choice = scan.nextInt();
                if(choice<0||choice>6)
                    throw new Exception();
            }catch(Exception e){
                System.out.println("Wrong input \n Enter again");
                scan.next();
                flag=true;
            }
        }while(flag);
        flag = true;
        switch(choice){
        case 1:{
            weather.WeatherRecord();
            break;
        }
        case 2:{
            weather.Average();
            break;
        }
        case 3:{
            weather.Maximum();
            break;
        }
        case 4:{
            weather.Minimum();
            break;
        }
        case 5:{
            weather.TotalPrecipitation();
            break;
        }
        case 6:{
            weather.Extremes();
        }
        default:{
            flag = false;
        }
        }
    }while(flag);
}

天气记录方法

    public void WeatherRecord(){
    boolean flag=true;
    do{
        try{
            flag=false;
    System.out.println("Enter date in MM/DD/2008");
    String str = scan.next();
    System.out.println(str);
    String [] str2 =str.split("/");
    int a =  Integer.parseInt(str2[0])-1;
    int b = Integer.parseInt(str2[1])-1;    
    for(int i=0;i<4;i++){
        System.out.printf("Loaction: %3s \t\t Date: %2s %2d,2008 \n",wrec[i][a][b].getlocation(),mon[a],(b+1));
        System.out.printf("High Temp: %3d \t\t\t Low Temp: %3d \n",wrec[i][a][b].getHigh(),wrec[i][a][b].getLow());
        System.out.printf("Avg Wind: %3d \t\t\t Max Wind %3d\n",wrec[i][a][b].getWinds(),wrec[i][a][b].getGusts());
        System.out.printf("Precipitaion: %3.2f inches\n \n",wrec[i][a][b].getPrecip());
        }
        }catch(Exception e){
            System.out.println("Wrong input \n Enter again");
            scan.next();
            flag=true;
        }
        }while(flag);   

    }

Answer 1

或者这个，更简洁，你不应该像以前那样使用异常。

do {
    choice = scan.nextInt();
    flag = choice < 0 || choice > 6
    if (flag)
        System.out.println("Wrong input \n Enter again");
} while(flag);

Answer 2

if (scan.hasNext())
  String str = scan.next();