尝试参数的命令行输出时出错

What is the error in following code while trying command line arguments ? I am getting an error at line System.out.println(args[i]);

在尝试命令行参数时,以下代码中的错误是什么?我在System.out.println(args [i])行收到错误;

 public class CommandLA{  
   public static void main(String []args)  
   {  
      int s = 0;  
      for(int i=0;i<args.length;i++)  
      System.out.println(args[i]);              
      s = s + Integer.parseInt(args[i]);  
      System.out.println("Sum is : "+s);  
   }  
 }

3 个解决方案

#1

maybe

public static void main(String []args)
{
   int s = 0;
   for (String str : args) {
      s = s + Integer.parseInt(str);
   }
   System.out.println("Sum is : "+s);
}

or using an indexed for

或使用索引

public static void main(String []args)
{
   int s = 0;
   for (int i = 0; i < args.length; i++) {
      s = s + Integer.parseInt(args[i]);
   }
   System.out.println("Sum is : "+s);
}

#2

Simple:

for(int i=0;i<args.length;i++)  
  System.out.println(args[i]);

followed by

s = s + Integer.parseInt(args[i]);

But - you are missing the { after the loop! Therefore the scope in which i exists (is visible) is only the line directly after the "for-loop" line!

但是 - 你错过了{循环之后!因此,i存在的范围(可见)只是“for-loop”行之后的行!

In other words you need for (..) { all stuff that uses i }!

换句话说,你需要(..){所有使用我的东西}!

#3

To elaborate on the answer of GhostCat:

详细说明GhostCat的答案:

for(int i=0;i<args.length;i++)  
System.out.println(args[i]);              
s = s + Integer.parseInt(args[i]);

is the same as

是相同的

for(int i=0;i<args.length;i++){
    System.out.println(args[i]);   
}           
s = s + Integer.parseInt(args[i]);

Which means that in the last line, i is not known, resulting in an error.

这意味着在最后一行,我不知道,导致错误。

I wonder why the error was detected at the line before, because until that, the code is technically correct.

我想知道为什么之前在该行检测到错误,因为在此之前,代码在技术上是正确的。

That said, I recommend to use brackets in any case. Some people omit them to get shorter code, but that means that if one adds a line later on, he could easily make a mistake. This is personal preference, of course.

也就是说,我建议在任何情况下都使用括号。有些人省略了它们以获得更短的代码,但这意味着如果稍后添加一行,他很容易犯错误。当然,这是个人偏好。

#1