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Java Class Q&A » Wrapper Class » Wrapper Class 2 

1. Double wrapper class    forums.oracle.com

2. Using Wrapper class method    forums.oracle.com

hi swati, it will show -1 because. when the type casting is done and the value is greater than the range of the data type then it wraps around the value. you have the value. 65535 and the range of byte is -128 to 127 i.e. 256. the value of (256*256) is 65536 thats why it is showing the value -1. ...

3. How to verify if a class is a wrapper?    forums.oracle.com

The usual wrapper types like: java.lang.BigDecimal java.lang.BigInteger java.lang.Boolean java.lang.Byte java.lang.Character java.lang.Double java.lang.Float java.lang.Integer java.lang.Long java.lang.Short All of these have one and only one Field wich name is "value", is that a good criteria to classify and handle them as a Wrapper? It is a serialization trick, there are other alternatives but not very clear, for example: all classes that are imediate ...

4. Wrapper classes & equals(), please clarify    forums.oracle.com

5. Whts the use of Wrapper classes    forums.oracle.com

You're not actually putting the primitives in the collection, the primitives are converted to the wrapper types. Some additional features that primitives don't provide are needed to use Collections. If you wanted to put an int into a HashMap, you would need the hashCode method defined by the wrapper class. There is no such method in the primitive type!

6. Use of Wrapper class    forums.oracle.com

8. Passing parameter to a wrapper class    forums.oracle.com

I have a wrapper class for a super class like this: public class WrapperClass () { super(some code here); } now I want to pass a parameter to this class when it's called. The existing call in the codebase is like this: WrapperClass.class.getName(); So if I add parameter to a class definition like this: public class WrapperClass (String param) { super(some ...

9. Wrapper Class methods    forums.oracle.com

Two's complement isn't all that straightforward, but it's not too hard once you really look at it. (Catch-22, I know.) The basics (I assume you know the first part, but I just want to make sure it's clear): A computer stores numbers in binary. So, for instance, an 8-bit number has spots for 8 binary digits, making the largest possible number ...

10. How do I use a Wrapper Class to double an Integer value?    forums.oracle.com

Hey Baftos, Thanks for the reply. Yes! I actually thought that it would double the value but perhaps I need to stick a value in the parenthesises...? Can I explain better what I am trying to achieve? Yes! I am trying to answer the following question from a past exam paper for a programming course: "Explain why Java has class versions ...

11. Wrapper class    forums.oracle.com

Hi shaolinf , For every primitive type in Java, there is a built-in object type called a wrapper class. For example, the wrapper class for int is called Integer; for double it is called Double. Wrapper classes are useful for several reasons: Each wrapper class contains the minimum and maximum values for the type and methods that are useful for converting ...

12. Convert Primitive to Wrapper Class    forums.oracle.com

13. wrapper class    forums.oracle.com

14. wrapper class    forums.oracle.com

16. Calling method in wrapper class in packaged jar causes EXCEPTION_ACCESS_VIO    forums.oracle.com

For one thing you know that the methods in the inner classes aren't declared correctly, right? No return values. Those nested classes are inner classes, which means that they have a reference to the nested class, and so you can't instantiate them without one. Apart from that... it's impossible to diagnose your issue without more info. Try writing a small, self-contained, ...

17. How to write a wrapper class    forums.oracle.com

I am new to the concept of wrapper classes. I have a small spell checker program that I need to access via a servlet by passing a string in and getting a string out with spelling suggestions. I could really use some advice on how to write a servlet that would do such a thing. TIA

18. What are the uses of Void wrapper class?    forums.oracle.com

19. Integer Wrapper Class    forums.oracle.com

} public void method(Integer i , Integer eii ) { System.out.println(i == eii ); } } Can anyOne help me to find how is this preceding code working?When case:1 calls then out comes "true" and When Case:2 executes "false" is a output. Please help me to find out why this different output coming while all variable have a values in int ...

20. Wat is Wrapper Class    forums.oracle.com

21. Class for primitive to class for corresponding wrapper?    forums.oracle.com

Is there any way to programmatically get hold of the class object for a primitive wrapper (eg Double.class) from the class object for the primitive type (eg double.class)? What about the reverse mapping? I can easily initilialize a Map of my own or write a method with if statements, but I'm curious if there is a library method somewhere. Or a ...

22. wrapper class instead of...    forums.oracle.com

23. Java Wrapper Class Integer - valueOf()    forums.oracle.com

24. Wrapper Classes    forums.oracle.com

So Java has primitives, like int, bool, char, etc. These are not objects, and cannot be treated like objects. This means that you cannot call methods on them. With the String class, you can call methods like charAt() to get information about the object. But say you have an int, and want information about it...what then?

25. Java Experts? Wrapper Classes HELP?    forums.oracle.com

Hi can anyone please help me and tell me if you can understand what this is asking effectively?; Use the Wrapper classes to output the maximum possible values of byte, short, int, long, float and double. Output should be on one line with space separated fields and in the order given. Output only the numbers requested and spaces , no other ...

26. Opinions on javadoc and wrapper classes    forums.oracle.com

I have several wrapper classes (in this case, wrappers for InputStream) that override all of the methods, but only a few of the methods overridden have important changes. The rest of the methods behave as described in the original contract (in this case, the various InputStream.read() methods). I would like to hear some opinions regarding documenting these methods. Any javadoc I ...

27. About wrapper and facade class    forums.oracle.com

If we continue this discussion someone could think to be in the wrong forum...we are talking about religion and philosophy and I am not so sure that computer science is better! Religion and philosophy often come up around here. And in CS in general, come to think of it. Particularly development. How many times have you sat at a hot compiler ...

28. how to write a wrapper class for an Object rather than an Interface    forums.oracle.com

The above inner implementation shows an example of a wrapper class. As you can see method query takes a String and a RowMapper as parameters. RowMapper is an interface and you make the implementation inside the method (you implement method mapRow). This is applicable only if the object you want is unique and you don't need it in another class. In ...

29. what is wrapper class atually done???    forums.oracle.com

30. float and Wrapper Class Float    forums.oracle.com

31. Passing primitive Wrapper class by reference    forums.oracle.com

It's about Integer (and other wrappers) being "immutable". Imutable classes don't allow any of their fields to be changed. If you passed, instead, a bean, with a single integer attribute then you could change the value of the field and it would be reflected in the calling code. But once you've created an Integer object you can't change it, only replace ...

32. Integer Wrapper Class    forums.oracle.com

It can't be done the way you wrote it, becaus Java always uses call-by-value, thus assigning to "container" in your example has no effect whatsoever on the caller. You'd have to use setValue() (which obviously does not exist for Integer, as it is immutable). You could write your own class "IntegerContainer" that simply holds an int (similar to what Integer does), ...

33. a doubt in wrapper classes    forums.oracle.com

i have a scjp question which iam finding conflicting answers..can anyone help me...The question in the book goes... Given that b and c refer to instances of wrapper classes, which two statements are true? (Choose two) A. b.equals(b) returns true. B. b.equals(c) returns the same result as b == c. C. b.eqials(c) can return false even if c.equals(b) returns true. D. ...

34. Regarding to wrapper class    forums.oracle.com

35. what is the use of Wrapper classes in Java?    forums.oracle.com

And not only would failure to initialize a Wrapper class object be obvious upon visual inspection, if you forget to initialize a wrapper like Float, you'll get a null pointer exception when you try to use it. With primitives, on the other hand, the compiler & JVM will quite happily use uninitialized variables with zero values, and quite often deliver plausible ...

36. What is the use of Wrapper classes ? Why i use Wrapper classes ?    forums.oracle.com

My question is that in java there are many wrapper classes. Why they are comes in pictures and what is the exact need to bring this new features in java. Without java it is also possible to programming so what is the actual needs ?. As i know one thing is that wrapper class is used to convert primitives types to ...

37. wrapper classes and ==    forums.oracle.com

The values from -128 to 127 are cached, so when you call Integer.valueOf(int x) for them, you'll get back a single instance, therefore the comparison == will return true. Outside of those values new instances are returned. And since the autoboxing mechanism uses Integer.valueOf(), you get that as result. Which is why you should NEVER compare objects with == (unless you ...

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