Dynamic Array Size

I am retrieving records from the database and need to populate them into a one dimensional Array.
I need to get the count of the RecordSet and then set the size of the Array.
Is there a method to know the number of rows retrieved into the RecordSet.
Thanks for your help.

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Dynamic array

how to implement dynamic array size in java...??
say if i want to add the element in an array then how should i do it..??

For dynamic array...Vector is the best one i
est one i think....
Sigh. Unless other code requires it (for example, JTable's DefaultTableModel),
Arraylist is preferred over the legacy class Vector.
And even then I wouldn't recommend ArrayList as the "best" list. What if the OP
wanted to have a FIFO queue? Would you recommend ArrayList/Vector over
LinkedList?

Increase array size dynamically

Hi Sir,
Balance is the class and current[]
is my array of object of class balance.
Balance current[] = new Balance[2];
Instead of assigning 2 to the array,
I only know the number of items in array
as I loop through my resultset.
So, meaning I don't know the array size
in before I create the array.
So, I need to increase the size of the
array as I loop through the resultset.
How can I achieve this?
Please advice.
Thanks.
null

get the ScrollableRowsetAccess from the ResultSetInfo and later you can get the getRowCount() with this number you can create the right size of the the array with the total of rows on the RowSetInfo or a ResultSetInfo. If your query is going to be growing after that point, you should better consider use vectors.
Carlos

Setting array size, effect on memory

Does setiing the array size to a huge no has any affect on the memory, performance and is it considered good programming. If not what are the other options?
String [] arrayString = new String [2354];

Your question is rather ambiguously worded.
In Java arrays cannot be resized, so you should set the array to the exact size you need. If you need a huge array, create one. If you need a small array, create one. If you don't know how large it should be, or need it to be dynamically sized, use any of these great classes - ArrayList, HashMap, HashSet, etc... Try reading the Java API documentation on these classes...
And yes, when you create a huge array, it actually allocates the space for each element in the array right then, and in fact initializes each with the default values of null, zero, or false depending on the type of the array.

Creating a dynamic Array

Thanks for reply.
I want to create a dynamic array and for this I used ArrayList Collection and Vector Class. I am using JDK 1.4.1 . But , I have a problem in that. In ArrayList, I used the following code:
ArrayList al = new ArrayList();
while(rs.next())
al.add(rs.getString("Enter_Year"));
al.add(rs.getString("UG_Production_Mi_Te"));
al.add(rs.getString("OC_Production_Mi_Te"));
al.add(rs.getString("Total_Production_Mi_Te"));
al.add(rs.getString("OBR_MM3"));
al.add(rs.getString("OMS_Te"));
al.add(rs.getString("Coal_Offtake_Mi_Te"));
al.add(rs.getString("Supply_to_Steel_Plant_Th_Te"));
al.add(rs.getString("Royalty_SalesTax_MP_Crs"));
al.add(rs.getString("Royalty_SalesTax_CG_Crs"));
al.add(rs.getString("Total_ManPower"));
al.add(rs.getString("Fatality_Rate_per_Mi_Te_Output"));
al.add(rs.getString("Total_Wellfare_Expenditure_Crs"));
String rpt[][] = new String[al.size()][];
rpt = al.toArray(rpt); // ArrayStoreExecption error
String colheads[] = {"...........My Table's Column names are here....."};
JTable table = new JTable(rpt,colheads);
JScrollPane jsp = new JScrollPane(table);
add(jsp);
At the statement having comment line I received the error ArrayStoreException. The JTable accepts the 2 D array for storing the info and I think the toArray() method is not working there and can't convert the ArrayList elements into an Array. Similarily, Vector Class is also not converting the elements into an array object and showing the same error only.
Please help me to convert it into an array object so that I can pass it into the JTable argument.

That isn't a jdbc problem but rather a collection problem.
You certainly can't convert a one dimensional collection into a two dimensional array automatically. And that is what you are creating with the while loop.
Since you know the column names you also know the inner array size so you can start by creating a statically sized string array (not collection) in the loop and add that to the outer collection. That might solve the problem.

Creating dynamic array

Can anybody tell me how to create a dynamic array in Java??I dont want to fix size of array,it should take any number of values at runtime.Please tell me the syntax of using dynamic arrays.

Hi,
For creating an array of similar data elements, use
ArrayList., but for storing elements which are in the
form of object then use Vector...
Best of Luck..
R SWrong... the main different between ArrayList and Vector is that Vector was sychronized and ArrayList are not.

Dynamic array to cluster

During runtime my main VI is loading a data file that is dynamic in size and content (created by another VI). It is loaded as a 1D array. I am looking to convert this array into a cluster of elements and display the titles and values of each element. I'm pretty sure I can figure out the labeling but I can't get the conversion to work dynamically... Can anyone help??
Scott@P&E

If your problem is to associate a name/label to each numerical value from the 1D array, you should consider using a 2D string array. The first column could contain the names and the second column the values. A Table control could do the trick very nicely.
CC
Chilly Charly (aka CC)
E-List Master - Kudos glutton - Press the yellow button on the left...

How can i maintain a dynamic array

I want to maintain an dynamic array in my code . It shoud grow accroding to no of user inputs . 1 can entre 5 numbers and other 10 , then array size should grow orderly 5 and 10 like that . Array is int array.

Read up on the Collections API. There is a tutorial on this site. At first blush, you want a List. If it will grow and you will not be removing and inserting constantly from the 'middle' of the list of items, then ArrayList is a logical choice as your List. Otherwise, use LinkedList. But definitely bone up on the tutorial. Understanding how Collections work is fundamental to any Java programming you will do.
- Saish

Store int values into dynamic array

Hello all,
I'm a newbie in JAVA whose want to store int values (coming from a resultset) into an dynamic array. I know that normally to create a "dynamic array" you'd better use a Vector, but it seems that I don't know how to use it correctly (throws me a exception as : Incompatible type for method. Can't convert int[] to java.lang.Object[]).
Thanks in advance
STF

I want to use the copyInto method of the vector, but it throw me an exception as ')' expected
I include a snip of my code below ;
Vector v= new Vector();
Vector vv=new Vector();
String[] labels=new String[v.size()];
Integer[] values=new Integer[vv.size()];
cont=rs.getInt("COUNT(CASE_ID_)");
vv.add(j,new Integer(cont));
log=rs.getString("ORIG_SUBMITTER");
v.add(j,new String(log));
v.copyInto(String[] labels);
vv.copyInto(Integer[] values);

Motion Assistant Contour Array Points - Optimal Array Size?

I am working with the NI Motion Assistant API and plyaing around with the Contour Move generation where I feed a set of X, Y target points to the Set Contour Move Properties.
One of the inputs is Profile Calculation Constraint - Array Size, Constraint Value (which would be the array size to use).
I am wondering if there is a way to calculate the "optimal" array size for any particular move? I know I can have too few - can I have too many points in an array (being reasonable here and not planning to use the whole 2^32 size allowed).
Thanks.
Ryan Vallieu
Automation System Architect

Hi Ryan,
Unfortunately, I'm not so sure I have a good answer for you. I'll evaluate some of the pros and cons below and then ultimately make a recommendation:
Constraint Type: Array Size
Pros
You always have a fixed sized array of setpoints. If you are using a 73xx card, this simplifies setting up your contour buffer. It also avoids using a lot of memory.
Cons
For long moves, you could have a long time and large distance between position setpoints. The motion card will do a spline interpolation to smooth the move, but the splining algorithm is only so good.
If you are sending the contour setpoints to a motion card, you don't know the interval between setpoints (although this isn't difficult to obtain).
Constraint Type: Sampling Time
Pros
Regardless of the move, you always have a fixed time between setpoints. As long as your sampling time isn't too large, even fast moves should execute accurately.
Cons
For a long move, you could generate a lot of setpoints that consume a lot of memory.
Setting up contouring buffers can be trickier.
Conclusion
It depends on what you expect the end customer to be doing. I prefer using the sampling time constraint since it is more robust for fast, long moves (and still good for slow, short moves). It will make creating contour buffers more difficult, but there is an example (Two-Axis Smart Contouring.vi) that shows how to dynamically update the buffer. Ultimately, I think it is better to focus on accurate moves than minimizing memory consumption.
If you decide to go with the sampling time method, I would start with a constraint value of .01, since 10msec is the shortest interval when configuring a contour buffer. Try and generate some position profiles to see how big the arrays are. For optimizing, it is just a tradeoff between array size and the accuracy of the generated motion profile.
Thanks,
Paul B.
Motion Control R&D

Data type of preprend array size in Flatten To String block

Hi
The data type of the preprend array size in Flatten To String block is given as I32. Is it somehow possible to reduce the data type to I8, since the width and height of my array won't exceed 255 ?. I also need to do the same in Unflatten To String as well.
Best regards
Oesen

Oesen wrote:
Hi
The data type of the preprend array size in Flatten To String block is given as I32. Is it somehow possible to reduce the data type to I8, since the width and height of my array won't exceed 255 ?. I also need to do the same in Unflatten To String as well.
The short answer is no. This is because the index is an I32. NI likes to keep integers as an I32 whenever possible for reasons like this.
Since you are dealing with a 2D array (width and height), it will actually use 2 I32s before the actual data.
As Ravens stated, you could put in your own array sizes before the array in the string. But it is worth saving 6 bytes? Not likely.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
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Change array size and delete duplicate row

Hello,
I am running a program that does a for loop 3 times. In each loop, data is collected for x and y points (10 in the example provided). How can I output the array with the 30 points in a simple 2D array (size 2x30)?
Also, from the array, how do I delete duplicate rows that contain the same x-value?
Thanks,
hiNi.
Solved!
Go to Solution.
Attachments:
array size.vi ‏10 KB

Hello,
THANK YOU for solving my first issue! Attached is the data set that contains the duplicate entries for the x-axis values. The y-axis value may be different, but not the x. I would like to delete the 2nd row that contains the same x-value.
Here is simple example of my input and desired output:
IN:
28.512000 -115.310532
28.812000 -86.937660
29.112000 -116.877052
29.412000 -87.223625
29.412000 -111.349045
30.012000 -86.510780
30.312000 -112.048187
OUT:
28.512000 -115.310532
28.812000 -86.937660
29.112000 -116.877052
29.412000 -87.223625
30.012000 -86.510780
30.312000 -112.048187
I am thinking of comparig the last x-axis value to the current one, and if it is the same, then not parse that row. The attached VI is as far as I got.
Any help will be greatly appreciated.
Thanks,
hiNi
Attachments:
delete duplicate row.vi ‏8 KB
data.txt ‏1 KB

Populating a dynamic array with objects and managing it in runtime.

So I'm another stuck firstyear. I'll try and make my question compact. I'm using Flash CS6 and have drawn an animated character on the stage that consists of separate parts that are animated and its head is a separate class/symbol entirely because it has not only animation, but a state switch timeline as well. This said Head extends the Main that is the character MovieClip.
I am using a dynamic array to store and .push and .splice objects of another class that would collide with this said Head.
I also discovered the super() function that is implicitly called as the constructor of the parent in any child class that extends the parent, in this case Head extends Main. The issue is that my collidable object array is populated within the main, within the function that spawns every next collidable object with a TimerEvent. This said function then gets called twice due to the super() call.
I have tried putting this super() call into an impossible statement in my child class, but it doesn't change a thing, and it was said that this method is unsafe so I don't even know if it should be working.
However what confuses me the most is when I trace() the .length of my collidable object array at the end of that function. As I said earlier, the original function both spawns an object after a period of Timer(1000) and adds it to the stage as well as adds the object onto the object array, but the super() constructor only duplicates the length call and a creates a copy of the object on the stage, but it does not add the second copy of the object onto the array. The trace() output goes on like so:
1
1
2
2
3
3
4
4
etc.
I wonder why and I'm really stumped by this.
Here is the code in question:
public class Main extends MovieClip {
                    public var nicesnowflake: fallingsnow;
                    var nicesnowflakespawntimer: Timer = new Timer(1000);
                    public var nicesnowflakearray: Array = new Array();
                    public function Main() {
                              nicesnowflakespawntimer.addEventListener(TimerEvent.TIMER, nicesnowflakespawn);
                              nicesnowflakespawntimer.start();
                    public function nicesnowflakespawn(event:TimerEvent) : void {
                              nicesnowflake = new fallingsnow;
                              nicesnowflake.x = Math.random()* stage.stageWidth;
                              nicesnowflake.y = - stage.stageHeight + 100;
                              nicesnowflakearray.push(nicesnowflake);
                              stage.addChild(nicesnowflake);
                              trace(nicesnowflakearray.length);
                              for (var i:Number = 0; i < nicesnowflakearray.length; i++){
                                        nicesnowflakearray[i].addEventListener(Event.ENTER_FRAME, snowhit);
                    public function snowhit(event:Event) : void {
                              if (nicesnowflakearray[0].y >= 460){
                                        if (nicesnowflakearray[0].y == stage.stageHeight) {
                                        nicesnowflakearray.splice(nicesnowflakearray.indexOf(nicesnowflake), 1);
                              //if (this.hitTestObject(nicesnowflake)){
                                        //trace("hit");
I am also fiddling with the collision, but I believe that it would sort itself out when I deal with the array pop and depop properly. However I'm pasting it anyway in case the issue is subtly hidden somewhere I'm not looking for it. And here is the child class:
public class Head extends Main {
                    public function Head(){
                              if (false){
                                        super();
                              this.stop();
So like what happens at the moment is that the array gets populated by the first object that spawns, but there is two objects on the stage, then when the objects reach stage.460y mark the array splices() the one object away and displays an error:
"#1010: A term is undefined and has no properties.
          at Main/snowhit()"
then when the next object spawns, it repeats the process. Why does it trace the array.length as "1, 1, 2, 2, 3, 3, 4, 4, 5, 5, etc" until the despawn point and then goes on to display an error and then starts from 1 again, because if the array length is more than one object at the time when the first object of the array gets spliced away, shouldn't it go on as usual, since there are other objects in the array?
Thank you very much to whomever will read this through.

There are multiple problems:
1. You should add eventlisteners for your objects only once, but you add eventlisteners every time your timer runs to all of your snowflakes, again and again:
                              for (var i:Number = 0; i < nicesnowflakearray.length; i++){
                                        nicesnowflakearray[i].addEventListener(Event.ENTER_FRAME, snowhit);
change it to
nicesnowflake.addEventListener(Event.ENTER_FRAME, snowhit);
I don`t see why its even necessary to employ this snowflakearray, it would be much straight forward if you simply let the snowflakes take care of themselves.
2. Then you have to change your enterframe function accordingly
public function snowhit(event:Event) : void {
                              if (e.currentTarget.y >= 460){
                                        if (e.currentTarget.y == stage.stageHeight) {
                                        e.currentTarget.removeEventlistener(Event.ENTER_FRAME, snowhit);
                                        removeChild(e.currentTarget);
3.
                              //if (this.hitTestObject(nicesnowflake)){
                                        //trace("hit");
since "this" is a reference to the Main class (root) it surely won`t function as you intend it to.
                              if (false){
                                        super();
makes no sense to use a condition that can never be true

Set Fixed Array Size

Hello. I am trying to develop a VI for an FPGA target and I'm trying to make it so whoever is using the VI can specify the size of an input array when they instantiate it (such as by having an input to the VI that says "max array size" or something). So far it seems like the only way to do something like this is to go into the VI itself and manually set the array size for each input array for the VI (i.e. open the VI, right click on each input array, select "Set Dimension SIze", choose "fixed", set number of elements). I'd like to have one point where I can set the size of all the arrays at once (since in my case they are all the same size), and let the person using the VI set it to the proper size for whatever application they are using it for (to be clear, let's say I have two uses for this VI, and in one case I have an input array of size 100 and in anohter use of size 1000, I'd like to be able to set these somehow instead of doing it through the dialog). Thanks.
Solved!
Go to Solution.

Unfortunately, per-call configuration of array size is not something that is supported today. This is a great idea, I would suggest that you post it on the FPGA Idea Exchange so we can get a feel for how many other people need this same feature.

How do I determine array size in a formula node

I am feeding an array into a formula node to perform an operation on. However the size of the array can be an arbitrary size. How can I determine its size to use for iterating through a for loop?
I suppose that I could add another input that is fed with the array size from the array palate but I would like to know if it can be done inside the formula node itself.

Your own advice is the only and best one.
greetings from the Netherlands

Dynamic Array Size

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