java - 我在第 : if ( args[0]. 行的 args[0] 中遇到异常数组索引超出范围等于 ("t") || args[0].equals ("time") ) 当我运行下面的代码时

Question

我在下面的代码中遇到了运行时异常ArrayIndexOutOfBoundException，行中:

if ( args[0].equals("t") || args[0].equals("time") )。

请帮我解决这个问题。

public static void main(String[] args)   {
   System.out.println("Starting Test Cases");
    try
    {
        // Parse the command line args
        int policy = 0;
        if ( args[0].equals("t") || args[0].equals("time") ) {
            policy = ResourceCharacteristics.TIME_SHARED`enter code here`;
        }
        else if ( args[0].equals("s") || args[0].equals("space") ) {
            policy = ResourceCharacteristics.SPACE_SHARED;
        }
        else {
            System.out.println("Error -- Invalid allocation policy....");
            return;
        }

        // determine which test case number to choose
        int testNum = Integer.parseInt(args[1]);
        if (testNum < MIN || testNum > MAX) {
            testNum = MIN;
        }

        ////////////////////////////////////////
        // First step: Initialize the GridSim package. It should be called
        // before creating any entities. We can't run this example without
        // initializing GridSim first. We will get run-time exception
        // error.
        Calendar calendar = Calendar.getInstance();
        boolean trace_flag = false;  // true means tracing GridSim events

        // list of files or processing names to be excluded from any
        // statistical measures
        String[] exclude_from_file = { "" };
        String[] exclude_from_processing = { "" };

        // the name of a report file to be written. We don't want to write
        // anything here.
        String report_name = null;

        // initialize all revelant variables
        double baudRate[] = {1000, 5000}; // bandwidth for even, odd
        int peRating[] = {10, 50};   // PE Rating for even, odd
        double price[] = {3.0, 5.0};   // resource for even, odd
        int gridletLength[] = {1000, 2000, 3000, 4000, 5000};

        // Initialize the GridSim package
        int totalUser = 2;    // total Users for this experiment
        GridSim.init(totalUser, calendar, trace_flag, exclude_from_file,
                exclude_from_processing, report_name);

        //////////////////////////////////////
        // Second step: Creates one or more GridResource objects
        int totalResource = 3;  // total GridResources for this experiment
        int totalMachine = 1;   // total Machines for each GridResource
        int totalPE = 3;        // total PEs for each Machine
        createResource(totalResource, totalMachine, totalPE, baudRate,
                       peRating, price, policy);

        /////////////////////////////////////
        // Third step: Creates grid users
        int totalGridlet = 4;     // total Gridlets for each User
        createUser(totalUser, totalGridlet, gridletLength, baudRate,
                   testNum);

        ////////////////////////////////////
        // Fourth step: Starts the simulation
        GridSim.startGridSimulation();
    }
    catch (Exception e)
    {
        System.out.println("Unwanted errors happen");
        System.out.println( e.getMessage() );
        System.out.println("Usage: java Test [time | space] [1-8]");
    }
    System.out.println("=============== END OF TEST ====================");
}

执行时会抛出异常，catch block 始终执行。

Answer 1

这意味着您的程序是在没有命令行或 IDE 模拟参数的情况下调用的，因此您的 args 的大小为 0 并引用索引 0将抛出ArrayIndexOutOfBoundsException。

如果您从命令行运行此程序，请添加程序参数(例如 java MyMainClass time)。

如果您在 IDE 中运行，则可以将参数添加到运行配置中。

在 Eclipse 中:

• 右键单击您的项目
• 选择运行/调试设置
• 编辑您所需的运行配置(通常只有一个)
• 选择参数选项卡
• 添加您的程序参数

注意

一个好的做法是在引用任何数组元素之前检查其大小，例如if (args.length > 0) {...}