传递命令行参数以在Java中复制文件名

Question

Is it possible to write a program from an IDE (such as NetBeans or Eclipse) that can compile from the command line and run once the user enters two arguments just after the name of the java class program to run?

If so, can an absolute path be passed in as one of the arguments?

And if so, (if the source or destination file has a multi-word descriptor, like Big Sky File.txt), how can it be passed in as an argument?

I know this is a lot of questioning, but I have searched high and low and nothing seems to so much as scratch the surface on any of these topics.

@Code-Guru, @thkala, here's the code I am attempting (took a bit to format):

edit: @Code-Guru, I have added the offending line (not sure how I missed that).

next edit: @ Code-Guru, here is the updated file contents from CopyFile.java, and the resulting error message:

import java.io.*;

public class CopyFile
{
 public static void main(String args[]) throws IOException, NullPointerException
{ 
int num; 
FileInputStream fileIn; 
FileOutputStream fileOut; 
try
{ 
  // open input file 
  try
  { 
    fileIn = new FileInputStream(args[0]); 
  }

  catch(FileNotFoundException e)
  { 
  System.out.println("Input File Not Found."); 
  return; 
  }

  // open output file 
  try
  { 
    fileOut = new FileOutputStream(args[1]); 
  }

  catch(FileNotFoundException e)
  { 
    System.out.println("Error Opening Output File.");
    return;
  }

}

catch(ArrayIndexOutOfBoundsException e)
{
  System.out.println("Incorrect argument use:java CopyFile Source Destination"); 
  return;
} 

// Copy File 
try
{ 
  do
  {
    num = fileIn.read();
    if(num != -1)
    {
      fileOut.write(num);
    }
  }

  while(num != -1); 
}

catch(IOException e)
{
  System.out.println("File Error: Could not copy file."); 
}
fileIn.close();
fileOut.close();
}
}

Here is the error message I receive from the command prompt:

Error: Could not find or load main class CopyFile

Answer 1

Is it possible to write a program from an IDE (such as NetBeans or Eclipse) that can compile from the command line and run once the user enters two arguments just after the name of the java class program to run?

Yes, it is possible.

If so, can an absolute path be passed in as one of the arguments?

Definitely - any string can be passed as an argument , as long as its size does not exceed a certain (usually system-defined) limit.

And if so, (if the source or destination file has a multi-word descriptor, like Big Sky File.txt), how can it be passed in as an argument?

Typically, arguments with spaces, special characters etc are handled by the calling shell, rather than the Java program. Consult your documentation on how to properly quote such arguments in whatever command line shell you are using.

Answer 2

The answer lies in this part of the error message:

(wrong name: copyfile/CopyFile)

Ie, your class's fully qualified name is copyfile.CopyFile . Java requires that the package layout match the folder layout on disk so it knows how to find things.

So either your class file must be in a subfolder called copyfile , and then invoked as java copyfile.CopyFile , or you can compile your class in the unnamed default package by removing the package copyfile; declaration from the code (you haven't shown that line, but it must be there).

More info: http://www.jarticles.com/package/package_eng.html