Float wrapper class??

[Joe San]

Guys,

The code below is from here

import java.util.*;
public class TechnoSample {
public static void main(String[] args) {
Vector col = new Vector();
col.add(new Integer(1));
col.add(new Integer("2"));
col.add(new Float(3.2d));//line 1
col.add(col.elementAt(1));
col.setElementAt(col.elementAt(2),0);
System.out.println(col);
}
}

Actually it compiles fine. I thought that it gives error at line 1?? Does the Float constructor accepts a double argument??? Also does a Double constructor accepts a float as argument?? How is all this possible??
[ December 19, 2006: Message edited by: Jothi Shankar Kumar Sankararaj ]

[Barry Gaunt]

Would someone please be kind enough look at the API for Float and Double and tell Jothi the answers. I'm just now feeling a little too lazy to bother to do it myself. :roll:

[Joe San]

Ok, I looked at the API and it says that Float has 3 constructors, one that takes a double as argument. Why didn't any of the books mention this one small thing in their wrapper class discussion?? I didn't find this in the K&B, Khalid Mughal...Is this not specific for the exam?? Only the Float class has 3 constructor?? Why is this so??

[Aniket Patil]

There are plent y of tiny "idiosyncracies" that are nowhere mentioned in K&B and probably other Java books. You need to explore them yourself.

[Joe San]

Do you know about any such other things?? If you can share that here, that would be of great help to all the ranchers.

[Edwin Dalorzo]

When I was studying for the SCJP exam I did a few things to avoid these pitfalls. I can recommend those same strategies to you. If you find them helpful then use them, otherwise just ignore my remarks.

One of the most important things that I did while studying for the exam is that I installed the JDK API documentation and I studied every single class in the java.lang and java.util package from it.

I never felt satisfy with a simple explanation of the book, I wanted to master every class. In order to do that I wrote dozens of examples with every class and I made a effort to understand what was the purpose of every single method. When I did the exam a couple of years ago I knew by heart every single class in the package, I knew static and non-static methods, their signatures and return types.

I also learned by heart the hierarchy of all collections.

All this may sound a bit exaggerated, it is up to you. All I can tell you is that it has really helped me a lot.

Something else I did that really helped me was to read the Java Language Specification.

Go over the examples in the Java Almanac.

And one of the most helpful things was trying to reply questions in this forum.

Sometimes I could not, but when I did not know the answer I did all the research to find out. Little by little I was replying to some questions myself.

So, keep up, and do not let this details let you down.

My final recommendation is: first research, and if you cannot find answer then ask. Even better if you ask for the place where the information is hidden instead of the answer itself, because when you do the research yourself it is not only more rewarding, but you learn things better.

[Joe San]

What you say is absolutely true. With just a week for my exam, I don't think that I will be able to do all of what you have said. Anyways, atleast for the Collections framework, I can do that and go. Thanks for the comments.

[Bert Bates]

Hi Guys, hi Edwin,

I'd like to give a little background about our intentions for the objectives we created for the exam. We certainly were not interested in having thousands of people memorizing tiny details about random aspects of the API. Instead, our intention was for people to understand the important aspects of some of the most commonly used packages. Our hope was that after studying the APIs in the objectives, candidates will have a good sense of how the APIs work in general, and how to use the docs.

So, long story short, you guys are certainly free to do the amount of memorization that Edwin is talking about, but imho it's not really necessary... either for the exam or for your Java future.

hth,

Bert