java.lang.ArrayIndexOutOfBoundsException: 0
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java.lang.ArrayIndexOutOfBoundsException: 0
提问by pg2014
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.
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。
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);
}
采纳答案by Joffrey
Problem
问题
This ArrayIndexOutOfBoundsException: 0means that the index 0is not a valid index for your array args[], which in turn means that your array is empty.
这ArrayIndexOutOfBoundsException: 0意味着该索引0不是您的数组的有效索引args[]，这反过来意味着您的数组为空。
In this particular case of a main()method, it means that no argument was passedon to your program on the command line.
在方法的这种特殊情况下main()，这意味着没有参数在命令行上传递给您的程序。
Possible solutions
可能的解决方案
If you're running your program from the command line, don't forget to pass 2 arguments in the command.
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 theArgumentstab for your run configuration and add some arguments in the program argumentsarea.
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。
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
Run > Run configurations...然后选择Arguments运行配置的选项卡，并在程序参数区域中添加一些参数。
Note that you should handle the case where not enough arguments are given, with something like this at the beginning of your main method:
请注意，您应该处理没有给出足够参数的情况，在 main 方法的开头使用类似的内容：
if (args.length < 2) {
System.err.println("Not enough arguments received.");
return;
}
This would fail gracefully instead of making your program crash.
这将优雅地失败，而不是使您的程序崩溃。
回答by Mureinik
This code expects to get two arguments when it's run (the argsarray).
The fact that accessing args[0]causes a java.lang.ArrayIndexOutOfBoundsExceptionmeans you aren't passing any.
此代码期望在运行时获得两个参数（args数组）。访问args[0]导致 a的事实java.lang.ArrayIndexOutOfBoundsException意味着您没有通过任何。
