Question about Object Arrays

I am getting compile time error of missing ']' on the second line
    dvdData[] data = new dvdData[4];
    data[0] = new dvdData("Casablanca", "Warner Brothers", "1942");
    data[1] = new dvdData("Citizen Kane", "RKO Pictures", "1941");
    data[2] = new dvdData("Singin' in the Rain", "MGM", "1952");
    data[3] = new dvdData("The Wizard of Oz", "MGM", "1939");the object dvdData is being declared correctly with 3 strings as constructors, can anyone tell me why it is doing this? I will post complete code if nessecary.

Hi,
I don't see any problem - check out my code :-
package project1;
public class DVDData
    String str1 = null;
    String str2 = null;
    String str3 = null;
    public DVDData(String str1,String str2,String str3)
        this.str1=str1;
        this.str2=str2;
        this.str3=str3;
    public String toString()
        return str1 + " : " +    str2 + " : " + str3;
    public static void main(String[] args)
        DVDData[] data = new DVDData[4];
        data[0] = new DVDData("Casablanca", "Warner Brothers", "1942");
        data[1] = new DVDData("Citizen Kane", "RKO Pictures", "1941");
        data[2] = new DVDData("Singin' in the Rain", "MGM", "1952");
        data[3] = new DVDData("The Wizard of Oz", "MGM", "1939");
        System.out.println(data[0]);
        System.out.println(data[1]);
        System.out.println(data[2]);
        System.out.println(data[3]);
}I get the correct output :-
Casablanca : Warner Brothers : 1942
Citizen Kane : RKO Pictures : 1941
Singin' in the Rain : MGM : 1952
The Wizard of Oz : MGM : 1939How are you comipling this ?
Regards,
Sandeep

Similar Messages

A question about Object Class

I got a question about Object class in AS3 recently.
I typed some testing codes as following:
var cls:Class = Object;
var cst:* = Object.prototype.constructor;
trace( cls === cst); // true
so cls & cst are the same thing ( the Object ).
var obj:Object = new Object();
var cst2:* = obj.constructor.constructor;
var cst3:* = obj.constructor.constructor.c.constructor;
var cst5:* = Object.prototype.constructoronstructor;
var cst4:* = Object.prototype.constructor.constructor.constructor;
var cst6:* = cls.constructor;
trace(cst2 === cst3 && cst3 === cst4 && cst4 === cst5 && cst5 === cst6); //true
trace( cst == cst2) // false
I debugged into these codes and found that cst & cst2 had the same content but not the same object,
so why cst & cst2 don't point to the same object?
Also, I can create an object by
" var obj:Object = new cst();"
but
" var obj:Object = new cst2();"
throws an exception said that cst2 is not a constructor.
Anyone can help? many thanks!

I used "describeType" and found that "cst2" is actually "Class" class.
So,
trace(cst2 === Class); // true
That's what I want to know, Thank you.

About Object Array!

why can't this diplay the elements of the ObjectArray in String?
the output is: [Ljava.lang.Object;@17943a4
Why??
THANKS!!
public class testing {
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as to why it prints the Object-Arrays String-representation rather than the output of the toString()-methods of it's contained objects, we'd probably have to ask Sun ;-)
but if you want a working implementation you might just write
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Question with object arrays..

This is my code and it doesn't seem to be working properly
public class familymember {
public familymember(){
Object[] array=new Object[500];
     public static void main(String args[]) {
     familymember array2 = new familymember();
     array2.array[51] = "500";
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I get the error message
Error : No variable array defined in class familymember.
familymember.java line 15 array2.array[51] = "500";
What am i doing wrong?

array cannot be accessed from outside it's block (in this case the constructor).
just change your code this way:
public class familymember {
private Object[] array; // or public or protected or whatever you want
public familymember(){
    array=new Object[500];
public static void main(String args[]) {
    familymember array2 = new familymember();
    array2.array[51] = "500";
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}

Question about an Array of objects

I'm writing a program that is supposed to store a String and a double in an array of CustomerBill objects. I just want to know if I am doing it correctly. Heres my code:
public static CustomerBill[] getCustomerData()
         //Local variables
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         double amt;
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      //Ask for the number of customers to be processed.
         System.out.print("How many customers are to be processed? ");
         numCust = Integer.parseInt(keyboard.nextLine());
         CustomerBill[] array = new CustomerBill[numCust];
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         System.out.println("\nPlease enter customer data when prompted.");
         System.out.println("Enter customer's last name, then first name.");
      //Get the customer data from user.
         for (int i = 0; i < array.length; i++)
           array[i] = new CustomerBill();
           System.out.print("\nCustomer name: ");
           customer = keyboard.nextLine();
           array.setName(customer);
System.out.print("Total bill amount: ");
amt = Double.parseDouble(keyboard.nextLine());
array[i].setAmount(amt);
System.out.println();
return array;

Write a test() method that:
(1) Gets an array of CustomerBills using getCustomerData()
(2) In a for-loop print out each of the CustomerBills. It will help if
CustomerBill has a toString() method but, in any case you should be
able to see that the aray contains the right number of nonnull elements.
Then write a main() method that calls the test() method.
[Edit] And then run it! You may need to do this a few times and check
what happens with "crazy" data.

Questions about Objects, pointers, and the memory that loves them

Hey,
This is all just a theoretical discussion so do understand that the code itself is not germane to the topic.
I have been mulling over the whole object release/retain/copy thing and need to understand a bit more the real inner workings of the beast. The catalyst for this is the repetitional fervor that most books on the subject of Objective C have employed. Yet they all seem to fail in a complete explanation of the whys and wherefores so that one can determine on her own the correct implementation of this.
Let's say I have an Object. For the fun of it it is an instance of NSObject and we'll call it myObject.
When I "create" this object thusly:
NSObject *myObject = [[NSObject alloc] init];
What I, in fact get back is a pointer to the object in question, yes?
So when I "seemingly" add this object to an array like:
NSArray *myArray = [[NSArray alloc] initWithObject:myObject];
What is actually placed in the array? is it another pointer to the original object created by myObject or is it a pointer to the pointer of myObject?
The reason I ask this is because I have run into a situation where some previous instructions on the subject have caused errors. I was told that if I did something like this and then passed the array to a calling method that I could release this array and it would then be the responsibility of the calling method to handle the memory. Further more if I place an object into an array and then copy it into another object of the same type as the original then I could release the array and still have the reference to the first object in the second object. When I have done this I get unpredictable results, sometimes the original object is there and sometimes it isn't
At what point should I release the array, after it is passed to the calling method (with the use of an autorelease) or when the class that it is encapsulated in is done?
Sorry about the length of this but I can't believe that I would be the only one that would be helped by such a discussion.
MM

etresoft,
Thanks for the detailed reply. I wish I could say that I wasn't still a bit confused by this. I thought I had this down after going through the lessons. It seems to not be working in practice the way that it works in theory.
My current project is an example
In a class I have declared a couple of ivars thusly:
NSMutableString *source;
NSMutableString *destination;
@property (nonatomic, retain) NSMutableString *source;
@property (nonatomic, retain) NSMutableString *destination;
This is followed by the appropriate @synthesize directives.
in the init method for my class I have the following:
source = [[NSMutableString alloc] initWithString:@"customer"];
destination = [[NSMutableString alloc] initWithString:@"home"];
in a method triggered by a button click I have the following:
if (sender == sourcePop){
source = [sourcePop titleOfSelectedItem];
}else{
destination = [destinationPop titleOfSelectedItem];
NSLog(@"SOURCE-%@", source);
NSLog(@"DESTINATION-%@", destination);
When I run the code and change the source selection the console reads the correct value for what is in the source popupbutton and "home" for the destination. If I then change the destination popupbutton I get a crash and nothing written to the console.
Placing a breakpoint at the beginning of the "if" and running shows me that just before the crash the source ivar is reported as "out of scope." There are no release or autorelease statements for this ivar anywhere in the class. Yet if I change the line that sets the ivar to the value of the popupbutton to this:
[source = [sourcePop titleOfSelectedItem] retain];
The debugger will have the correct value for the ivar and when run normally there is no crash.
I would assume that the problem is that the ivar is being released but I am not the one releasing it. Why does this behavior happen? Shouldn't the retain count still be 1 since the @property directive has it and there is no release in the code? Or is it that the statement that sets the ivar to the value of the popup really just setting it to the pointer and it is the popup that is somehow being released?
Is there something else that I should be doing?
MM

Javascript question about objects

Hi,
Let's say I've created a new object. One of the properties of my object
is an array. I would like another property to return the length of that
array. How do I do this.
For instance here's some code (and I hope that the email interface
doesn't screw this up so badly to make it unreadable. I'm going to avoid
using square brackets as well by using round ones instead even though
it's a syntax error, since square ones are known not to work with email.)
function test(){
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x = new test();
x.a(0) = 3;
x.a(1) = 3;
x.b;
Returns 0. In other words, just setting this.b = this.a.length doesn't
not get updated automatically as this.a is added to.
Now, I tried turning this.b into a method (ie this.b = function(){return
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to refer to myObject.b().
How can I avoid that? How can I have a built-in length property for an
object.
Hope this is clear and has come out legibly via email. Apologies in
advance if it hasn't.
Thanks,
Ariel

Hi all,
1) About the original question—which doesn't regard prototype inheritance in itself: "How can I have a built-in length property for an object"—I think the most obvious approach is to directly use an Array as the base object. Since any Array is an Object you can append methods and properties to it while keeping benefit from the whole array's API:
var myData = [];
myData.myProp = 'foo';
myData.myMeth = function(){ return [this.myProp, this.length, this.join('|')]; };
// Usage
myData[0] = 10;
myData[1] = 20;
alert( myData.myMeth() ); // => foo,2,10|20
// etc.
2) Now, if for whatever reason you cannot use the previous technique or need to deal with a precustomized Object structure such as:
var myObj = {
    items: [],
    meth: function(){ alert("Hello World!"); },
    // etc.
then the challenge is more difficult for the reasons that Jeff mentioned above. You can anyway mimic a kind of 'binding' mechanism this way:
// The original obj
var myObj = {
    items: [],
    meth: function(){ alert("Hello World!"); }
// Adding length as a 'fake property' (getter and setter)
(myObj.length = function F(n)
    if( !F.root )
        (F.root=this).watch('length', function(_,ov,nv){ F(nv); return ov; });
        F.valueOf = function(){ return F().valueOf(); };
        F.toString = function(){ return F().toString(); };
    if( 'undefined' == typeof n )
        n = F.root.items.length >>> 0;
    else
        F.root.items.length = n;
    return n;
}).call(myObj);
// Usage
myObj.meth(); // => Hello World!
myObj.items[0] = 10;
myObj.items[1] = 20;
alert( myObj.length ); // => 2
var x = myObj.length-1; // works too, thanks to F.valueOf
alert( x ); // => 1
myObj.length = 5; // testing the setter
alert( myObj.length ); // => 5
alert( myObj.items ); // => 10,20,,,
Of course it's totally unreasonable to implement such an artillery just for the convenience of writing myObj.length instead of myObj.length()—and myObj.length=x instead of myObj.length(x)—so I only suggest this for the sake of experimentation.
@+
Marc

A question about objects and queries

I just started using COM objects in ColdFusion. I am mostly
using CreateObject, but occasionaly use <CFOBJECT>
My question is; Do I have to destroy these object variables
when I am done? I know in a lot of other languages I work in, you
have to "clean up'" after yourself and destroy some variables when
you are done to avoid memory leaks. How does CF handle this?
While I am asking, what about queries? Do hey have to be
destroyed as well? What about queries made with QueryNew?
Thank you for the help.

Cold fusion cleans up for you.
You do not need to explicitly destroy anything unless threads
are spawned in a non standard way by Java or C code that you are
using.

Question about C array initialization

I understand that the statement
char string[] = "chars";
initializes string[5] to 0 ('\000'). My question is does the statement
char *strings[] = { "string1", "string2", "string3" };
initialize strings[3] to (void *) 0, i.e. NULL? I can't find the answer to this question in the ansi standard. GCC seems to tack on a NULL pointer at the end (even with the -ansi and -pedantic-errors flags), which is really convenient for finding the boundary, but I'm not sure whether it's a GCC thing or an official C thing. I see where the standard talks about terminating char arrays initialized by a string literal with a null byte, but it doesn't talk about the analogous case with arrays of pointers.
Last edited by nbtrap (2012-06-25 03:18:20)

nbtrap wrote:
Not necessarily. A declaration like:
char arr[3] = "str";
doesn't get null-terminated.
It doesn't get null-terminated because you don't leave enough room in the array for the null character. "char arr[3]" can only contain 3 characters, the same way that "char arr[2] = "str" will only contain 2. The second example generates a warning whereas the first does not, but only because it is very common to work with non-null-terminated strings.
nbtrap wrote:
And besides, my point is that initializing strings[3] *would* make sense for the same reason that intializing
char foo[] = "bar";
with a terminating null byte *does* make sense.
I know that arrays of pointers are not the same. My questions assumes that much. The fact of the matter is, however, GCC terminates pointer arrays of unknown size with a null pointer, and my question is simply "is this an ansi C thing or a GCC thing?".
In fact, it seems that GCC terminates all arrays of unknown size that are explicitly initialized with the appropriate number of null bytes. For example:
struct tag { int i; char c; char *str; } tags[] = {
{ 1, 'a', "string1" },
{ 2, 'b', "string2" },
{ 3, 'c', "string3" }
initializes tags[3] to sizeof (struct tag) null bytes. Try it for yourself.
I get the following:
test.c
#include <stdio.h>
int
main(int argc, char * * argv)
int i;
char *strings[] = { "string1", NULL, "string3"};
for (i=0;i<5;i++)
printf("strings[%d]: %s\n", i, strings[i]);
return 0;
output
strings[0]: string1
strings[1]: (null)
strings[2]: string3
Segmentation fault
test2.c
#include <stdio.h>
#include <string.h>
int
main(int argc, char * * argv)
int i;
struct tag {int i; char c; char *str;};
struct tag null;
memset(&null, 0, sizeof(struct tag));
struct tag tags[] =
{ 1, 'a', "string1" },
// { 2, 'b', "string2" },
null,
{ 3, 'c', "string3" }
for (i=0;i<5;i++)
printf(
"tags[%d]: (%p) %1d %c %s\n",
i, tags + i, tags[i].i, tags[i].c, tags[i].str
return 0;
output
tags[0]: (0x7fffd2df4e80) 1 a string1
tags[1]: (0x7fffd2df4e90) 0 (null)
tags[2]: (0x7fffd2df4ea0) 3 c string3
tags[3]: (0x7fffd2df4eb0) 0 (null)
Segmentation fault
The above behavior appears to conflict.
Given that string constants in C are defined as null-terminated, i.e. "str" is equivalent to "{'s', 't', 'r', '\0'}", the assignment 'arr[] = "str"' explicitly includes a null terminator. The other examples above do not include such a terminator. Even if it would be convenient sometimes, the standard should adopt a minimally invasive approach. It's easy to add a NULL at the end of an array declaration, but impossible to remove an extra element from such a declaration.
This may be informative too:
test3.c
#include <stdio.h>
#include <string.h>
int
main(int argc, char * * argv)
char str[] = "test";
char *strings[] = {"string1", NULL, "string3"};
struct tag {int i; char c; char *str;};
struct tag null;
memset(&null, 0, sizeof(struct tag));
struct tag tags[] =
{ 1, 'a', "string1" },
// { 2, 'b', "string2" },
null,
{ 3, 'c', "string3" }
printf(
"str\n size: %lu\n length: %lu\n"
"strings\n size: %lu\n length: %lu\n"
"tags\n size: %lu\n length: %lu\n",
sizeof(str), sizeof(str)/sizeof(char),
sizeof(strings), sizeof(strings)/sizeof(char *),
sizeof(tags), sizeof(tags)/sizeof(struct tag)
return 0;
output
str
size: 5
length: 5
strings
size: 24
length: 3
tags
size: 48
length: 3
The string length (actual number of chars in array) is reported as 5 ('t', 'e', 's', 't', '\0'), which is expected. The array of strings and tags are both reported as 3, even though you can access a null value after the last initialized index of the tags array. If that null value was really supposed to be there, it should be accounted for using sizeof, just as the null character is in the string.
Maybe the ultimate null element of the tags array is some artefact of memory alignment.

Question about object retention and scope

I have a hole in my understanding of Cocoa.
I can create temp objects, to populate an array with, like this:
for(int i=0;i<10;i++)
myObject *tmpObj= [[[myObject alloc] init]] ;
[[myMutableArray addObject:tmpObj]];
[[tmpObj release]];
But I don't understand why this works. If the tmpObjects get released, then why don't the ones in the array get released? (I can access the array later, and it is populated with myObjects.)

If you create an object from scratch (alloc, etc) then it's up to you to release it.
If you get an object from another method of the system you don't have to worry about releasing it. More than likely it's set to auto-release but it's not your responsibility.
If you want to hold on to any object then you retain it if you didn't create it. Any object you've retained you're responsible for releasing.
If you pass an object before releasing it's up to that object to hold on to it if it needs it.
Links:
http://www.stepwise.com/Articles/Technical/2001-03-11.01.html
http://developer.apple.com/documentation/Cocoa/Conceptual/MemoryMgmt/Tasks/Memor yManagementRules.html
Article on leaks
http://www.cimgf.com/2008/04/02/cocoa-tutorial-fixing-memory-leaks-with-instrume nts/

Question about objects

Hi
I make a number of objects, they are all from the same class but have differing values.
I put the objects into different arrays
I put all the objects in a hash table so that i can associate the object with a string.
tempOb = create.make()
compFd= tempOb; //
tempStr = compFd[i].returnTextValue();
theRef.put(tempStr, tempCard);
My question is where do the objects actually exist - and where are they only a reference to the object ? I ask because i am thinking that maybe its uneccsary to make arrays for objects when i could simply have string arrays and use the string to take the object from the hash table.
Thanks

Hi
I make a number of objects, they are all from the same
class but have differing values.
I put the objects into different arrays
I put all the objects in a hash table so that i can
associate the object with a string.
tempOb = create.make()
compFd= tempOb; //
tempStr = compFd[i].returnTextValue();
theRef.put(tempStr, tempCard);
My question is where do the objects actually exist -
and where are they only a reference to the object ? I
ask because i am thinking that maybe its uneccsary to
make arrays for objects when i could simply have
string arrays and use the string to take the object
from the hash table.
Thanks
FIrst of all you need to revisit what an object is?
An object is a self-contained entity which has its own private collection of properties (ie data) and methods (ie. operations) that encapsulate functionality into a reusable and dynamically loaded structure. After a class definition has been created as a prototype, it can be used as a template for creating new classes that add functionality. Objects are programing units of a particular class. Dynamic loading implies that applications can request new objects of a particular class to be supplied on an 'as needed' basis. Objects provide the extremely useful benefit of reusable code that minimizes development time. As far as the storage is concerned and all object variables are references.

Question about Object Oriented Design in Oracle

Hi everyone,
Right now I'm updating my oracle skills, years ago without programming (last time with Oracle 7.3 :O)
Well, if I have to design a new system with this features:
1.- Using Oracle as DB
2.- Web enable
3.- OO Design
My questions:
1.- What is the best practice to make database design? E-R + Object Types? I mean is better making the design on Oracle directly or in Java-UML environment?
2.- I was thinking in programming with Forms, but it works well with OO design?
3.- If I want to program some web services based, Could I do it with PL/SQL and Jdeveloper?
please if you know about articles and whitepapers about OO design approach with Oracle let me know!
Thanks.

I have been involved in some of these projects that have used Java, C#, VB, C++ etc. as front-end languagaes. I have been able to implement these projects successfully using the following approach:
1. create a relational model of the database - third-normal form (assuming it is an OLTP application)
2. Write PL/SQL code (packages and procedures mainly)
3. Interact with the front-end layer by sending and receiving ref curosors and/or PL/SQL tables
If you want to use Forms (I am assuming Oracle Forms) then there may not be much need for an OO design. Embeeding SQL in the forms will do most of what you want.
Shakti
http://www.impact-sol.com
Developers of Guggi Oracle - Tool for DBAs and Developers

Question about using arrays

I have a web page written with combination of Front Page and Java is included. I have 4 drop down boxes which work in sequence. select an item in the first, it then asks you to select in the second box, then 3rd then in the final 4th box. This was set up using arrays. My question is how can i put a hyperlink to the items in the last drop down box? I want the last selection to go to a URL. can you tell me what code i need to use and where to insert it? I assume it has to go into the array somewhere. Thanks, Tom

selection to go to a URL. can you tell me what code
i need to use and where to insert it? Not without you clarifying your question and showing the relevant bits of your code, and possibly not even then.
When you post code, please use[code] and [/code] tags as described in Formatting tips on the message entry page. It makes it much easier to read.
I assume it
has to go into the array somewhere. I assume it doesn't, because code doesn't go into arrays.

Easy question about objects

why with this code;
private Scanner x;
public void openfile(){
try {
x = new Scanner(new File(chinese.txt));
why do you say x is a variable at private scanner x and then make x an object? why do both variable and object? the code is from http://www.youtube.com/watch?v=3RNYUKxAgmw
Edited by: 980099 on Jan 19, 2013 4:30 PM
Edited by: 980099 on Jan 19, 2013 4:38 PM
Edited by: 980099 on Jan 19, 2013 4:42 PM

why do you say x is a variable at private scanner xThe code doesn't actually say it's a variable, but it is. It is a reference of type Scanner. As it isn't initialized in the declaration, its initial value is null.
and then make x an object? It doesn't. it creates a new Scanner instance and then assigns the reference to 'x'.
why do both variable and object?You should now be able to see that the question is meaningless.

A question about Object Manager

Hello, a question set the server with the installation wizard, select all ObjMgr of application, but I have none running on the server, only the following:
srvrmgr> comp list for server SERVER
CC_ALIAS SV_NAME CC_NAME CT_ALIAS
   CC_RUNMODE CG_ALIAS CP_DISP_RUN_STATE CP_STARTMODE CP_NUM_RUN_TASKS CP
CP_ACTV_MTS_PROCS MAXTASKS CP_MAX_MTS_PROCS CP_START_TIME CP_END_TIM
E CC_INCARN_NO CC_DESC_TEXT
SERVER FSMSrvr FSMSrvr File System Manager
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SERVER ServerMgr ServerMgr Server Manager
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                                                 2012-06-29 16:52:34
SRBroker SERVER Server Request Broker ReqBroker
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0 1 1 2012-06-29 16:52:34
Server Request Processor SERVER SRProc SRProc
   Interactive Running Auto SystemAux February 20
            1 1 2012-06-29 16:52:39
SvrTblCleanup SERVER Server Tables Cleanup BusSvcMgr
   Background Running Auto SystemAux January 1
                                                 2012-06-29 16:52:39
SvrTaskPersist Server SERVER Task Persistence BusSvcMgr
   Background Running Auto SystemAux January 1
                                                 2012-06-29 16:52:39
SERVER Siebel Administrator Notification Component AdminNotify AdminNotif
Auto Online and Batch SystemAux 0 10
            1 1 2012-06-29 16:52:39
Siebel Connection Broker SCBroker SERVER SCBroker
   Background Running System Auto 1 January
                                                 2012-06-29 16:52:34
8 rows returned.
how I can change others?

Sebastian,
You can run command below using srvrmgr:
enable compgrp callcenter
Callcenter component group has call center Object Manager. You need to restart the Siebel Server after running this command. Check link below for further details:
http://docs.oracle.com/cd/E14004_01/books/SystAdm/SystAdm_SrvrMgrCLI12.html#wp1004864
You may need to assign the component group to a specific siebel server.
Thanks,
Wilson

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