So when I compile, everything will compile just fine.

When I go to run the program, I get this error

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
	at ClientForNoDupCollection.main(ClientForNoDupCollection.java:20)

I go to look at line 20(actually 19-21)

public static void main(String args[]) {
		File file = new File(args[0]);
		Scanner cReader = null;

I'm attempting to be able to do command line execution of the files.

I'm not 100% sure where I went wrong there.

When you run, how did you run it? If you use IDE (not command line execution), you may not pass the argument in the command to the method. As a result, your args[] array is size 0.

// correct command line
java ClientForNoDupCollection myfile.ext
// if the myfile.ext exists, it is OK here
// if it doesn't exist, File class will throw NPE

// incorrect
java ClientForNoDupCollection

Edited 5 Years Ago by Taywin: n/a

So I tried what you referred to.

I get this error now.

java.lang.NullPointerException
	at ClientForNoDupCollection.main(ClientForNoDupCollection.java:41)

Looked at line 41.

while (cReader.hasNext())

Looks like it's referring back to the top...as being null.

Then you need to show me your whole class code then. I can't pinpoint how it happen by seeing only this much portion of the code. :(

So I tried what you referred to.

I get this error now.

java.lang.NullPointerException
	at ClientForNoDupCollection.main(ClientForNoDupCollection.java:41)

Looked at line 41.

while (cReader.hasNext())

Looks like it's referring back to the top...as being null.

Uhm ...

public static void main(String args[]) {
		File file = new File(args[0]);
		Scanner cReader = null;
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