線程「main」中的異常java.lang.ArrayIndexOutOfBoundsException：0在proj5.main（proj5.java:15）

Question

編譯我的程序時出現此錯誤。

異常線程 「main」 java.lang.ArrayIndexOutOfBoundsException：0 在proj5.main（proj5.java:15）

當我雙擊錯誤它引導我「字符串起源= ARGS [ 0];」

這裏是整個代碼：

import java.io.BufferedReader; 
import java.io.FileReader; 
import java.io.IOException; 

public class proj5 { 

    public static void main(String[] args) { 
     //validates command line 
     if(args == null || args.length != 6){ 
      System.out.println("Invalid command line arguments"); 
      System.out.println("Usage: Project5 [origin] [minSpeed] [maxSpeed] [maxBoxcars] [inputFile] [outputFile]"); 
     } 

     //gets arguments   
     String origin = args[0]; 
     int minSpeed = Integer.parseInt(args[1]); 
     int maxSpeed = Integer.parseInt(args[2]); 
     int maxBoxcars = Integer.parseInt(args[3]); 
     String inputFile = args[4]; 
     String logFile = args[5]; 

     //create new train log 
     TLog log = new TLog(logFile); 
     try { 
      log.createFile(); 
     }catch(Exception ex){ 
      System.out.println("Failed to create output file"); 
     } 

     //create train 
     Train train = new Train(origin, minSpeed, maxSpeed, maxBoxcars, log); 
     //read file 
     readFile(inputFile, train); 
    } 

    private static void readFile(String inputFile, Train train){ 
     boolean quit = false; 

     BufferedReader br = null; 

     try { 
      String line; 

      //reader for file 
      br = new BufferedReader(new FileReader(inputFile)); 
      //loop until end of file or quit 
      while (!quit && ((line = br.readLine()) != null)) { 
       //get commands 
       if(line.equals("PRINT")){ 
        //PRINT 
        train.logCommand("PRINT", new String[]{}); 
        train.printStatus();      
       } else if(line.equals("ARRIVE")){//ARRIVE 
        train.logCommand("ARRIVE", new String[]{}); 
        train.setArrived(); 
       } else if(line.equals("DEPART")){//DEPART 
        String city = br.readLine(); 
        train.logCommand("DEPART", new String[]{city}); 

        train.setDeparted(city); 
       }else if(line.equals("SPEEDUP")){//SPEEDUP 
        int mph = Integer.parseInt(br.readLine()); 
        train.logCommand("SPEEDUP", new String[]{String.valueOf(mph)}); 
        train.speedUp(mph); 
       }else if(line.equals("SLOWDOWN")){//SLOWDOWN 
        int mph = Integer.parseInt(br.readLine()); 
        train.logCommand("SLOWDOWN", new String[]{String.valueOf(mph)}); 
        train.slowDown(mph); 
       }else if(line.equals("ADDCAR")){//ADDCAR 
        String type = br.readLine(); 
        int maxElements = Integer.parseInt(br.readLine()); 
        BoxCar boxCar = null; 
        //Create new boxcar based on type 
        if(type.equals("PERSON")){ 
         boxCar = new PersonCar(maxElements); 
        }else if(type.equals("CARGO")){ 
         boxCar = new Car(maxElements); 
        } 

        train.logCommand("ADDCAR", new String[]{type, String.valueOf(maxElements)}); 
        train.addCar(boxCar); 

       }else if(line.equals("REMOVECAR")){ //REMOVECAR 
        int carNum = Integer.parseInt(br.readLine()); 
        train.logCommand("REMOVECAR", new String[]{String.valueOf(carNum)}); 
        train.removeCar(carNum);      
       }else if(line.equals("LOAD")){//LOAD 
        String cargoType = br.readLine(); 
        int boxCarId = Integer.parseInt(br.readLine()); 
        String id = br.readLine(); 

        CarContents carContents = null; 
        //create contents based upon cargo type 
        if(cargoType.equals("PERSON")){ 
         String name = br.readLine(); 
         int age = Integer.parseInt(br.readLine());     
         carContents = new Person(id, name, age);        
         train.logCommand("LOAD", new String[]{String.valueOf(boxCarId), id, name, String.valueOf(age)}); 
        } else if(cargoType.equals("CARGO")){ 
         int weight = Integer.parseInt(br.readLine()); 
         int height = Integer.parseInt(br.readLine()); 
         int width = Integer.parseInt(br.readLine()); 
         int length = Integer.parseInt(br.readLine());      
         carContents = new Cargo(id, weight, height, width, length); 
         train.logCommand("LOAD", new String[]{String.valueOf(boxCarId), String.valueOf(weight), String.valueOf(height), 
           String.valueOf(width), String.valueOf(length)}); 
        } 

        train.load(boxCarId, carContents); 

       }else if(line.equals("UNLOAD")){//UNLOAD 
        int boxCarId = Integer.parseInt(br.readLine()); 
        String cargoId = br.readLine(); 
        train.logCommand("UNLOAD", new String[]{String.valueOf(boxCarId), cargoId}); 
        train.unload(boxCarId, cargoId); 

       }else if(line.equals("QUIT")){//QUIT 

        train.logCommand("QUIT", new String[]{}); 
        train.logMessage("Quitting..."); 
        quit = true; 
       }   
      } 

     } catch (IOException e) { 
      e.printStackTrace(); 
     } finally { 
      try { 
       if (br != null) 
        br.close(); 
      } catch (IOException ex) { 
       ex.printStackTrace(); 
      } 
     } 

    } 
} 

請讓我知道如果你需要的其他類，我有BoxCar.java，Car.java，CarContents.java，CarException.java，Cargo.java， Person.java，PersonCar.java，TLog.java和Train.java。

這是我得到的唯一錯誤，它阻止我編譯和運行該程序。

Answer 1

你似乎沒有傳遞任何參數，所以如何訪問參數的位置0？

Answer 2

如果錯誤是在行：

String origin = args[0]; 

那麼就意味着你沒有提供任何運行時參數到您的程序。

儘管您對參數進行了檢查，但您沒有采取任何糾正措施，只是在if塊之後繼續執行。您可能需要將您的代碼的其餘部分else塊，以避免ArrayIndexOutOfBoundException：

 //validates command line 
     if(args == null || args.length != 6){ 
      System.out.println("Invalid command line arguments"); 
      System.out.println("Usage: Project5 [origin] [minSpeed] [maxSpeed] [maxBoxcars]   [inputFile] [outputFile]"); 
     } else { 
      //rest of the code 
     }