Difference between javac and eclipse compiler

I have the following code:
public class Test {
     public static void main(String[] args) {
          Integer i = 0;
          double d = 1.5d;
          i += d;
          System.out.println(i);
}javac gives me the following error:
Test.java:5: inconvertible types
found   : double
required: java.lang.Integer
                i += d;
                     ^
1 errorThe Eclipse compiler, however, gladly compiles and the JRE runs it, outputting "1".
The question is: which compiler is correct?
javac version 1.6.0_04
java version "1.6.0_04"
Java(TM) SE Runtime Environment (build 1.6.0_04-b12)
Java HotSpot(TM) Client VM (build 10.0-b19, mixed mode, sharing)
Eclipse JDT version 3.3.1.r332_v20080131

Integer is probably 32-bit while Double is 64-bit.
Your code is doing the following;
- widening the original Integer to Double,
- performing double-precision addition,
- assigning the double-precision result to the original Integer.
Without an explicit cast, your code is asking the compiler to implicitly narrow the double, potentially throwing away data.

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Whatz the difference between jdk and jre

i would like to know the difference between jdk and jre.

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The JDK(Java Developmental Tool kit) comes along with java libraries and JVM embedded in it. Apart from these it comes along with the utility tools for byte code compilation "javac", Executing the byte codes through java programmes through "java" and many more utilities found in the binary directory of java. Speaking practically JDK is essential for developers, which comes along with library packages to develop Software programmes. While JRE is minimal set of programmes which executes the java class files developed by the software developers.

What is the difference between netbeans and JDK ?

What is the difference between netbeans and JDK ?
This is because i got netbeans 5.5 ide and nothing else and still i ran some hello world programs successfully. . ..
i am confused - - does jdk come combined with netbeans ?

What is the difference between netbeans and JDK ?
This is because i got netbeans 5.5 ide and nothing
else and still i ran some hello world programs
successfully. . ..
i am confused - - does jdk come combined with
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wht is da difference between void and null w.r.t java?

corlettk wrote:
Why do you care, unless you're implementing a java compiler or JVM?Wow, you sure do suck at helping out in a forum. Why even make this post? You're not helping the OP any, and you made yourself look like a tool.
To the op:
Null is java's version of a null value. Java's version is more strict then many other languages, and will not work in a boolean expression or anywhere code expects a real and not null value. It's simply null.
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Difference between mtl_system_items and mtl_system_items_b

Hi All,
Can anyone tell me the difference between mtl_system_items and mtl_system_items_b ?
Regards,
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What's the difference between boxing and unboxing?

What's the difference between boxing and unboxing, I'm a bit confused?
Is autoboxing the same as boxing?
This is what I know so far:
-This is boxing, i think:
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I did little research, but please correct me ifI'm
wrong:
Is this similiar to unboxing:
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intArray[2]);
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Arrays and collections aren't subject to
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fill in constructs such as Integer.valueOf() for you,
it doesn't go as far as generating loops and new
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OP, as Peter said, the difference between boxing and
unboxing is merely one of direction. Autoboxing wraps
a primitive up for you, auto-unboxing extracts the
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Differences between CAF and NWDS

Hi all,
I'm reading about CAF and I don't understand the differences between CAF and NWDS. In NWDS you can composite an aplication with services offered by other systems, so I don't understand what CAF offers.
Regards,

Hi,
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thanks

Hi,
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What are the differences between inactive and active ABAP objects?

Can anybody tell me what are the differences between inactive and active ABAP objects?
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Hi,
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With a create, there is no active version, until you hit the activate button. This means ONLY you can run the program.
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Difference between Macros and subroutine

Hi all,
What is the difference between the macros subroutine and function module functinalitywise.;

Hi,
Macros can only be used in the program the are defined in and only after the definition.
Macros can take max 9 parameters.
Macros are expanded at compilation / generation.
Subroutines (FORM) can be called from both the program the are defined in and other programs ('perform
' of 'perform in program ').
Subroutines can take any amount of parameters.
Subroutines are 'expanded' at runtime.
Functions are just like FORMs, but are intended to be called external.
Some differences between FUNCTIONs and FORMs:
The name of a FORM must be unique within the program (two programs can have different FORMs with the same name). A FORM is intended to be called internal (from within the program, however by a 'trick' you can call them external).
The name of a FUNCTION has to be unique throughout the system. A FUNCTION is intended to be called external (and is thus shared by 'many' programs).
The latter is more important for programmers and maintenance. Since a FUNCTION is called external, it is important to keep the interface (parameters) the same. The interface of a FORM (which is intended to be called internal) is check when debugging a program (but it is only checked within the program that is debugged). So if the interface of a FORM is changed, but the call to the FORM (perform ) is not, the debugger will notice this and issue an error message.
In general:
A MACRO is more or less an abbreviation for some lines of code that are used more than once or twice.
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A FUNCTION is (more or less) a subroutine that is called external.
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--Excerpt from http://sap.ittoolbox.com/documents/popular-q-and-a/macro-vs-subroutine-1594#
DATA p_c(10).
FIELD-SYMBOLS: <fs> TYPE ANY.
DATA p_old1 TYPE i VALUE 10.
DATA p_old2 TYPE i VALUE 11.
DATA p_old3 TYPE i VALUE 12.
DATA p_old4 TYPE i VALUE 13.
DATA p_old5 TYPE i VALUE 14.
DATA p_old6 TYPE i VALUE 15.
DATA p_old7 TYPE i VALUE 16.
DATA p_old8 TYPE i VALUE 17.
DATA p_old9 TYPE i VALUE 18.
DATA p_old10 TYPE i VALUE 19.
DATA p_old11 TYPE i VALUE 21.
DATA p_old12 TYPE i VALUE 22.
DATA p_old13 TYPE i VALUE 23.
DATA p_old14 TYPE i VALUE 24.
DEFINE ADD_MAPPING.
p_c = &1.
CONDENSE p_c.
CONCATENATE 'p_old' p_c INTO p_c.
ASSIGN (p_c) TO <fs>.
WRITE <fs>.
END-OF-DEFINITION.
DO 14 TIMES.
ADD_MAPPING sy-index.
ENDDO.
http://sap.ittoolbox.com/documents/popular-q-and-a/macro-vs-subroutine-1594
http://help.sap.com/saphelp_nw2004s/helpdata/en/9f/db972835c111d1829f0000e829fbfe/frameset.htm
Regards,
Priyanka.

Difference between implements and extends

Hi all,
what is the difference between implements and extends. i am sorry to ask this silly question, but i am new to JAVA.
Thanks
Balaji

when you extend a class, your class that you are coding inherits every method and field from the extending class. For example:
public class CustomFrame extends JFrame {
//Your class's methods will be in here, but so will all of JFrame's methods.
}You can override (most) methods from extended classes if you want them to do different things than they normally do. The most commonly overriden methods when using swing are stuff like paint(Graphics g). It needs to be overriden to repaint all of the components.
When you imlpement something, you have to specify an interface. Interfaces have methods in them with no code. If you implement an interface, all methods in in must be defined. If not, the code will not compile. Some interfaces like ActionListener extend other classes to perform stuff. The actionPerformed(ActionEvent e) method will perform an action when a button is pressed, etc.

Difference between Macros and subroutines

Hi experts can any one tell difference between macros and subroutines.

1) Macros can only be used in the program the are defined in and only after the definition are expanded at compilation / generation. Subroutines (FORM) can be called from both the program the are defined in and other programs . A MACRO is more or less an abbreviation for some lines of code that are used more than once or twice. A FORM is a local subroutine (which can be called external). A FUNCTION is (more or less) a subroutine that is called external. Since debugging a MACRO is not really possible, prevent the use of them (Ive never used them, but seen them in action). If the subroutine is used only local (called internal) use a FORM. If the subroutine is called external (used by more than one program) use a FUNCTION
2) The macros, which we may use,
(stored in table TRMAC)
, we cannot debug that code.
3) where as in subroutine,
its a abap code, directly visile in
the editor,
and we can debug this code.
4) MACROS =>
Getting a feel of macros
The basic syntax of macros is as follows:
DEFINE macro_name. "Macro Definition
. Statements
. Statements
END-OF-DEFINITION. "Macro Definition
macro_name par1 par2 par9. "Macro call -parameters separated by spaces
Within the DEFINE... and END-OF-DEFINITION lies the body of the macrothe statements that you wish to be executed each time the macro is called. These statements may be any valid ABAP statements, such as WRITE, CLEAR, FORM calls, or database statements such as SELECT or UPDATE.
To familiarize yourself with the working of macros, it's necessary to take a close look at exactly what happens when an ABAP program containing a macro call is generated. Consider Listing A.
All ABAP programs must be generated before they can be executed. At the time of program generation, the system supplants each macro call, as shown in Listing A, with the statement(s) placed between the macro definition. Furthermore, the parameters passed at the time of macro calling are copied in place of the any placeholders (numbered &1, &2 &9) found in the body of the macro definition. The system simply ignores the presence of the macros during the execution of the programthat is, all statements are executed as a single block of code:
write : int1.
write : int2.
write : int3.
Other than readability and meaningfulness, macros also offer performance advantages. For testing purposes, I wrote a macro that incremented the value of a variable by 1 and called the macro N times via a DO loop, as shown here:
DEFINE INCREMENT.
ADD 1 TO &1.
END-OF-DEFINITION.
DO N TIMES.
INCREMENT VAR1.
ENDDO.
SUBROUTINES=>
Subroutines
You call subroutines from ABAP programs using the PERFORM statement.
Subroutines are introduced with the FORM statement and concluded with the ENDFORM statement.
You can define subroutines in any ABAP program. You can either call a subroutine that is part of the same program or an external subroutine, that is, one that belongs to a different program. If you call an internal subroutine, you can use global data to pass values between the main program and the subroutine. When you call an external subroutine, you must pass actual parameters from the main program to formal parameters in the subroutine.
*U Shud start rewarding helpfull answers*
amit

Difference between mailroutingsmarthost and daemon

I would like to know the difference between mailroutingsmarthost and daemon usage. When to use mailroutingsmarthost and when to use daemon?
Thanks in advance.

MailRoutingSmarthost is placed in LDAP for a domain.
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LDAP entries require no restart.
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Difference between procedure and function

hi
please give solution to below discussion:
Interviewer: What is the difference between Procedure and Function ?
Myself: Procedure may or may not return a value and can return multiple values and Function must return a value.
Interviewer : Can function return multiple values ?
myself: Yes, It can return multiple values.
Interviewer: Then, there is no need to use procedures any more, according to your previous answer (function can return multiple values) "we can do all the things by using procedures by using functions". Then why there is differentiation between procedure and function ?
myself : no reply (simply frustated at this question)
The above is conversation between me and interviewer.
Please suggest me what would be my reply to above topic.
In one book i find that using functions we can return multiple values but it is poor programming practice.
why this is a programming practice ?
please suggest me solution
thanks in advance
prasanth as.

Another difference is function must return something. There is no such restriction on procedure.In fact, a procedure CANNOT contain an expression in its RETURN statement.
SQL> create or replace procedure test_return is
2 begin
3    return(10) ;
4 end ;
5 /
Warning: Procedure created with compilation errors.
SQL> show errors
Errors for PROCEDURE TEST_RETURN:
LINE/COL ERROR
3/3      PLS-00372: In a procedure, RETURN statement cannot contain an
         expression
3/3      PL/SQL: Statement ignored
SQL>And, a procedure cannot be called as part of a expression (it must be a function).
SQL> create or replace procedure test_return is
2 begin
3    return ;
4 end ;
5 /
Procedure created.
SQL> variable x number ;
SQL> exec :x := test_return ;
BEGIN :x := test_return ; END;
ERROR at line 1:
ORA-06550: line 1, column 13:
PLS-00222: no function with name 'TEST_RETURN' exists in this scope
ORA-06550: line 1, column 7:
PL/SQL: Statement ignored
SQL>

What is the difference between JDK and J2ee

Could someone explain, in simple terms, what is the difference between JDK and J2ee. I am trying to understand the difference.
THanks

Could someone explain, in simple terms, what is the
difference between JDK and J2ee. I am trying to
understand the difference.You can practice on this one first. What's the difference between chalk and cheese? No just kidding.
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Difference between javac and eclipse compiler

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