java.lang.ArrayIndexOutOfBoundsException: 0 [英] java.lang.ArrayIndexOutOfBoundsException: 0

问题描述

我正在用一本书学习 Java.有一个我无法正常工作的练习.它使用 java 类 Double 添加两个双精度值.当我尝试在 Eclipse 中运行此代码时，它给了我标题中的错误.

I am learning java using a book. There is this exercise that I can't get to work properly. It adds two doubles using the java class Double. When I try to run this code in Eclipse it gives me the error in the title.

public static void main(String[] args) {

    Double d1 = Double.valueOf(args[0]);
    Double d2 = Double.valueOf(args[1]);
    double result = d1.doubleValue() + d2.doubleValue();
    System.out.println(args[0] + "+" + args[1] + "=" + result);

}

推荐答案

问题

这个 ArrayIndexOutOfBoundsException: 0 意味着索引 0 不是数组 args[] 的有效索引，这反过来意味着你的数组是空的.

Problem

This ArrayIndexOutOfBoundsException: 0 means that the index 0 is not a valid index for your array args[], which in turn means that your array is empty.

在 main() 方法的这种特殊情况下，这意味着没有参数被传递到命令行上的程序.

In this particular case of a main() method, it means that no argument was passed on to your program on the command line.

• 如果您从命令行运行程序，请不要忘记在命令中传递 2 个参数.

• If you're running your program from the command line, don't forget to pass 2 arguments in the command.

如果您在 Eclipse 中运行您的程序，您应该在运行配置中设置命令行参数.转到<代码>运行>运行配置...，然后为您的运行配置选择Arguments 选项卡，并在程序参数 区域中添加一些参数.

If you're running your program in Eclipse, you should set the command line arguments in the run configuration. Go to Run > Run configurations... and then choose the Arguments tab for your run configuration and add some arguments in the program arguments area.

请注意，您应该处理没有提供足够参数的情况，在 main 方法的开头使用类似这样的内容:

Note that you should handle the case where not enough arguments are given, with something like this at the beginning of your main method:

if (args.length < 2) {
    System.err.println("Not enough arguments received.");
    return;
}

这会优雅地失败，而不是让你的程序崩溃.

This would fail gracefully instead of making your program crash.

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