Question

编译程序时出现此错误。

线程“main”中的异常java.lang.ArrayIndexOutOfBoundsException：0 在proj5.main（proj5.java:15）

当我双击错误时，它会指示我“String origin = args [0];”

以下是整个代码：

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();
            }
        }

    }
}

如果您需要其他课程，请告诉我，我有BoxCar.java，Car.java，CarContents.java，CarException.java，Cargo.java，Person.java，PersonCar.java，TLog.java和Train的.java。

这是我遇到的唯一错误，它阻止我编译并运行程序。

Answer 1

如果错误在行：

String origin = args[0];

然后它意味着您没有为您的程序提供任何运行时参数。

虽然您检查了参数，但是您没有采取任何纠正措施，只是在if阻止后继续执行。您可能希望在else块中移动其余代码以避免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
        }

Answer 2

你似乎没有传递任何参数，那么如何访问args的位置0？

线程“main”中的异常java.lang.ArrayIndexOutOfBoundsException：0在proj5.main（proj5.java:15）

2 个答案: