Head First error

[Adam Prebola]

I get the following error when trying to compile an example from the book.

MyEx.java:5: class ExTestDrive is coderanch, should be declared in a file named ExTestDrive.java
public class ExTestDrive {
^
1 error


Here is the example.



class MyEx extends Exception { }

public class ExTestDrive {

public static void main(String[] args) {

String test = args[0];

try {

System.out.print("t");
doRisky(test);
System.out.print("o");

} catch (MyEx e) {

System.out.print("a");

} finally {

System.out.print("w");

}

System.out.print("s");

}

static void doRisky(String t) throws MyEx {

System.out.print("h");

if ("yes".equals(t)) {

throw new MyEx();

}

System.out.print("r");

}

}

[Keith Lynn]

There can only be one public top-level class in a source file, and the name of that source file must match exactly with the name of the public class. Java is case-sensitive.

[marc weber]

Hi Adam, welcome to JavaRanch!

Compiler errors are usually pretty good at telling you what's wrong. In this case...

MyEx.java:5: class ExTestDrive is coderanch, should be declared in a file named ExTestDrive.java

...tells you that there's a problem on line 5 of your file MyEx.java. Specifically, you've declared a public class called "ExTestDrive" that needs to be declared in a file called "ExTestDrive.java."

The reason behind this error is that the Java compiler allows no more than one public class definition per source file -- and the file must share the name of that public class. So in other words, if you have a public class called ExTestDrive, then it needs to be in a file called ExTestDrive.java.

[Vishwas Hegde]

"Cuius rei demonstrationem mirabilem sane detexi hanc marginis exiguitas non caperet." ~Pierre de Fermat

[marc weber]

Originally posted by Vishwas Hegde:
...

Wikipedia: Fermat's Last Theorem.

[Adam Prebola]

Wow! That was fast. I guess I should've said, I understand the error and why, but this is a book for beginners. However, it doesn't state to make a seperate file. So I would assume that I should put all the code in one file. Does this seem odd?

[Vishwas Hegde]

Thanks marc...

In my humble opinion... It would have been easier to all, if you had written it in English....

Anyways.. thanks

Regards
Vishwas Hegde

[marc weber]

Originally posted by Vishwas Hegde:
... It would have been easier to all, if you had written it in English...

I think the original Latin is more likely to prompt people to Google and discover the background that makes this quote so intriguing (and even humorous in this context). An English translation would likely be taken at face value.
[ February 21, 2006: Message edited by: marc weber ]

[Keith Lynn]

Yeah. Fermat was great.

[marc weber]

Originally posted by Keith Lynn:
Yeah. Fermat was great.

And Sir Andrew Wiles!

One of my favorite books is Fermat's Enigma by Simon Singh. (A NOVA episode called "The Proof" was based on this book. Here's a transcript.)