Question

代码在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出异常

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);
}

weatherRecord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

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

Answer 2

或者更简洁，你不应该像你那样使用异常。

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

扫描仪输入中的例外情况

2 个答案: