Gahhhr - stuck ...Generics? OOP-2

[Katrina Owen]

I can't seem to find the solution to this.

Let's say, hypothetically, that I have a Map where I store a String as the key, and an Integer object as the value, but I haven't actually told the Map that this is what is going in.

Then I say...

Integer first = (Integer)map.get( someString );

Would this cause my compiler to get sore at me?

My compiler is definitely getting sore, I am just having trouble figuring out how I've managed to offended it.

[Katrina Owen]

Went back to my compiler. It is telling me the following:

Note: NaturalLanguageMultiply.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

When I recompile as directed, I am told repeatedly (once for every addition to my Map):

NaturalLanguageMultiply.java:9: warning: 
[unchecked] unchecked call to put(K,V) as a member of the 
raw type java.util.Map
        numbers.put( "someString", someNumber );

I don't actually say someString and someNumber - this is illustratory.

What is it that I am not getting?
[ February 07, 2007: Message edited by: Katrina Owen ]

[Nathan Leniz]

I did a little bit of searching and this is what I found about Xlint:unchecked
-Xlint:unchecked
Give more detail for unchecked conversion warnings that are mandated by the Java Language Specification.

I found that here if it interests you more.

It still compiles, just throws a warning. If you add a

 @SuppressWarnings("unchecked")   

above main it will suppress compile time warnings that would otherwise be thrown if the string matches the type of warning, at least that's how I'm reading the language spec. It's here if you want to read more.

From what I can tell of reading both, you can't suppress warnings the spec explicitly says to throw from the compiler, you have to do it in the code with a suppression.

Edited to add, all that is if you don't parameterize.
[ February 07, 2007: Message edited by: Nathan Leniz ]

[Marilyn de Queiroz]

You can ignore those warnings. Java 5 spits them out when you write Java 4 code with a Java 5 compiler. I think there is a flag you can use when you compile to avoid that, but other than being a nuisance, it's not a problem.

try these:
javac -source 1.4
javac -target 1.4

They worked for me.

If you implement Nathan's suggestion, you won't get the warnings either, but they won't compile for my 1.4 compiler (because of the '@')
[ February 08, 2007: Message edited by: Marilyn de Queiroz ]

[Katrina Owen]

Thanks both of you - I thought it was a problem with my code being wrong - I don't mind the compiler complaining, as long as I am coding in an acceptable fashion!