I am passing some parameters in the URL and then I add them in a list. My list has a limit of 5 elements. So if someone adds 6th element in the URL the list would simply ignore it. So I am trying to use a counter but the logic is not working as desired. I am using While loop to achieve this. So if list size is smaller than 5 set the agencyCds otherwise just return the list.
private List<IUiIntegrationDto> generateViewIntegrationReportData(ESignatureIntegrationConfig eSignConfig) throws Exception {
int counter = 1;
if(eSignConfig.getAdditionalAgencyCds() != null ) {
List<String> combinedAgencyCds = new ArrayList<String>();
for(String agencyCd : eSignConfig.getAgencyCd()) {
combinedAgencyCds.add(agencyCd);
}
StringTokenizer token = new StringTokenizer(eSignConfig.getAdditionalAgencyCds().toString(), StringConstants.COMMA);
while(token.hasMoreTokens()) {
combinedAgencyCds.add(token.nextToken());
}
while(combinedAgencyCds.size() < 5) {
counter = counter + 1;
eSignConfig.setAgencyCd(combinedAgencyCds);
}
// eSignConfig.setAgencyCd(combinedAgencyCds);
}
List<IUiIntegrationDto> intgList = getUiIntegrationManager().retrieveUiIntegrationReportData(eSignConfig.getAgencyCd(), eSignConfig.getCreatedDays(),
eSignConfig.getLob(), eSignConfig.getTransactionStatus(), eSignConfig.getAccounts(), eSignConfig.getSortKey(), eSignConfig.getSortOrder());
return intgList;
}
I am not completely sure about this logic if it is correct or if there is nay better approach.
Thanks
Try this instead of the last while in your code:
if(combinedAgencyCds.size() <= 5) {
eSignConfig.setAgencyCd(combinedAgencyCds);
} else {
eSignConfig.setAgencyCd(combinedAgencyCds.subList(0, 5));
}
The full combined list will then be used if it is less than 5 in size. Otherwise, only the first 5 elements are used.
Edit: Or even better:
eSignConfig.setAgencyCd(combinedAgencyCds.subList(0, Math.min(5, combinedAgencyCds.size())));
Ok so let's break down what your code is currently doing.
int counter = 1;
while(combinedAgencyCds.size() < 5) {
counter = counter + 1;
eSignConfig.setAgencyCd(combinedAgencyCds);
}
This snippet of code has a couple things wrong best I can tell. First, this loop has the possibility of running forever or not at all. Because combinedAgencyCds is never being manipulated, the size won't ever change and the logic being checked in the while loop never does anything. Second, there's a more efficient loop for doing this, assuming you don't need the counter variable outside of its usage in the while loop and that is using for loops.
Example syntax is as follows:
for (int i = 0; i < combinedAgencyCds.size(); i++) {
if (i < 5) {
// Do your logic here.
}
else {
break; // Or handle extra values however you want.
}
}
Notice there is no need for the explicit declaration for a counter variable as "i" counts for you.
Now in your actual logic in the loop, I'm not sure what the setAgencyCd method does, but if it simply sets a list variable in the eSignConfig like it appears to, repeating it over and over isn't going to do anything. From what I can see in your code, you are setting a variable with the same value 5 times. If you need any more explanation just let me know and I will be happy to revise the answer.
I am having a weird issue with java list. Please see the code below:
for ( int i=0; i < tripList.size(); i++ ) {
ModeChoiceTrip trip = tripList.get(i);
int newUniqueId = tripListIds[trip.uniqueId];
int newLinkedId = trip.linkedId >= 0 ? tripListIds[trip.linkedId] : -1;
int jointTripNum = trip.linkedId >= 0 && trip.tourType != TourTypes.SPECIAL_EVENT ? jointTripListIds[trip.linkedId] : 0;
trip.uniqueId = newUniqueId;
trip.linkedId = newLinkedId;
trip.jointTripNum = jointTripNum;
}
In the above code, the values in tripList seem correct but after executing a few iterations (up to i = 6), the values in tripList changes for all the positions.
I cannot provide the whole source code here but showing the snippet of the code where I have an issue.
I found that there are some duplicate trips in tripList. When one of the trips is changed, the copy of it (located at different position) is also changed.
I am guessing this piece of code is executed by multiple threads, Then there is every chance that List could be modified by another thread while this loop is going on.
you could try synchronizing the loop and see if issue gets resolved.
Also, you could try using for-each loop instead of the loop with counter.
for (ModeChoiceTrip trip : tripList) {
.....
}
The issues was the duplicate values in the list. Thus, when I update a value in list the copy to that value changes as well
You set the unique id to -1. So if the trip list id comes in as -1, you grab the index like tripListIds[-1]; which might be the second to the last item in the list.
I am looping through an array in a java transform, writing some of the elements to outputs in the same row (passive).
The loop stops at the 1st iteration
for (int c = 1 ; c < arr.length; c++){
String fldname = String.valueOf(c);
int fldIdx = Integer.parseInt(prop.getProperty(fldname));
if( isOutFldProjected( fldname) &&
(!isSetNullCalled( fldname))){
outputBuf.setString(outRowNum, fldIdx, arr[c]);
}
If your arr contains 16 elements and it exiting in first iteration, it must throw some kind of Error or Exception. Which you should be getting at output console.
Or Loop may be iterating 16 times but without meeting your if condition :
if( isOutFldProjected( fldname) && (!isSetNullCalled( fldname)))
Try debugging.
If I missed any info please provide.
Post the detailed information. Unable to understand the whole problem.
But I think your arr[] has only one element in it.
I got a weird problem.
I thought this would cost me few minutes, but I am struggling for few hours now...
Here is what I got:
for (int i = 0; i < size; i++){
if (data.get(i).getCaption().contains("_Hardi")){
data.remove(i);
}
}
The data is the ArrayList.
In the ArrayList I got some strings (total 14 or so), and 9 of them, got the name _Hardi in it.
And with the code above I want to remove them.
If I replace data.remove(i); with a System.out.println then it prints out something 9 times, what is good, because _Hardi is in the ArrayList 9 times.
But when I use data.remove(i); then it doesn't remove all 9, but only a few.
I did some tests and I also saw this:
When I rename the Strings to:
Hardi1
Hardi2
Hardi3
Hardi4
Hardi5
Hardi6
Then it removes only the on-even numbers (1, 3, 5 and so on).
He is skipping 1 all the time, but can't figure out why.
How to fix this? Or maybe another way to remove them?
The Problem here is you are iterating from 0 to size and inside the loop you are deleting items. Deleting the items will reduce the size of the list which will fail when you try to access the indexes which are greater than the effective size(the size after the deleted items).
There are two approaches to do this.
Delete using iterator if you do not want to deal with index.
for (Iterator<Object> it = data.iterator(); it.hasNext();) {
if (it.next().getCaption().contains("_Hardi")) {
it.remove();
}
}
Else, delete from the end.
for (int i = size-1; i >= 0; i--){
if (data.get(i).getCaption().contains("_Hardi")){
data.remove(i);
}
}
You shouldn't remove items from a List while you iterate over it. Instead, use Iterator.remove() like:
for (Iterator<Object> it = list.iterator(); it.hasNext();) {
if ( condition is true ) {
it.remove();
}
}
Every time you remove an item, you are changing the index of the one in front of it (so when you delete list[1], list[2] becomes list[1], hence the skip.
Here's a really easy way around it: (count down instead of up)
for(int i = list.size() - 1; i>=0; i--)
{
if(condition...)
list.remove(i);
}
Its because when you remove an element from a list, the list's elements move up. So if you remove first element ie at index 0 the element at index 1 will be shifted to index 0 but your loop counter will keep increasing in every iteration. so instead you of getting the updated 0th index element you get 1st index element. So just decrease the counter by one everytime you remove an element from your list.
You can use the below code to make it work fine :
for (int i = 0; i < data.size(); i++){
if (data.get(i).getCaption().contains("_Hardi")){
data.remove(i);
i--;
}
}
It makes perfect sense if you think it through. Say you have a list [A, B, C]. The first pass through the loop, i == 0. You see element A and then remove it, so the list is now [B, C], with element 0 being B. Now you increment i at the end of the loop, so you're looking at list[1] which is C.
One solution is to decrement i whenever you remove an item, so that it "canceles out" the subsequent increment. A better solution, as matt b points out above, is to use an Iterator<T> which has a built-in remove() function.
Speaking generally, it's a good idea, when facing a problem like this, to bring out a piece of paper and pretend you're the computer -- go through each step of the loop, writing down all of the variables as you go. That would have made the "skipping" clear.
I don't understand why this solution is the best for most of the people.
for (Iterator<Object> it = data.iterator(); it.hasNext();) {
if (it.next().getCaption().contains("_Hardi")) {
it.remove();
}
}
Third argument is empty, because have been moved to next line. Moreover it.next() not only increment loop's variable but also is using to get data. For me use for loop is misleading. Why you don't using while?
Iterator<Object> it = data.iterator();
while (it.hasNext()) {
Object obj = it.next();
if (obj.getCaption().contains("_Hardi")) {
it.remove();
}
}
Because your index isn't good anymore once you delete a value
Moreover you won't be able to go to size since if you remove one element, the size as changed.
You may use an iterator to achieve that.
for (Iterator<Object> it = data.iterator(); it.hasNext();) {
if ( it.getCaption().contains("_Hardi")) {
it.remove(); // performance is low O(n)
}
}
If your remove operation is required much on list. Its better you use LinkedList which gives better performance Big O(1) (roughly).
Where in ArrayList performance is O(n) (roughly) . So impact is very high on remove operation.
It is late but it might work for someone.
Iterator<YourObject> itr = yourList.iterator();
// remove the objects from list
while (itr.hasNext())
{
YourObject object = itr.next();
if (Your Statement) // id == 0
{
itr.remove();
}
}
In addition to the existing answers, you can use a regular while loop with a conditional increment:
int i = 0;
while (i < data.size()) {
if (data.get(i).getCaption().contains("_Hardi"))
data.remove(i);
else i++;
}
Note that data.size() must be called every time in the loop condition, otherwise you'll end up with an IndexOutOfBoundsException, since every item removed alters your list's original size.
This happens because by deleting the elements you modify the index of an ArrayList.
import java.util.ArrayList;
public class IteratorSample {
public static void main(String[] args) {
// TODO Auto-generated method stub
ArrayList<Integer> al = new ArrayList<Integer>();
al.add(1);
al.add(2);
al.add(3);
al.add(4);
System.out.println("before removal!!");
displayList(al);
for(int i = al.size()-1; i >= 0; i--){
if(al.get(i)==4){
al.remove(i);
}
}
System.out.println("after removal!!");
displayList(al);
}
private static void displayList(ArrayList<Integer> al) {
for(int a:al){
System.out.println(a);
}
}
}
output:
before removal!!
1
2
3
4
after removal!!
1
2
3
There is an easier way to solve this problem without creating a new iterator object. Here is the concept. Suppose your arrayList contains a list of names:
names = [James, Marshall, Susie, Audrey, Matt, Carl];
To remove everything from Susie forward, simply get the index of Susie and assign it to a new variable:
int location = names.indexOf(Susie);//index equals 2
Now that you have the index, tell java to count the number of times you want to remove values from the arrayList:
for (int i = 0; i < 3; i++) { //remove Susie through Carl
names.remove(names.get(location));//remove the value at index 2
}
Every time the loop value runs, the arrayList is reduced in length. Since you have set an index value and are counting the number of times to remove values, you're all set. Here is an example of output after each pass through:
[2]
names = [James, Marshall, Susie, Audrey, Matt, Carl];//first pass to get index and i = 0
[2]
names = [James, Marshall, Audrey, Matt, Carl];//after first pass arrayList decreased and Audrey is now at index 2 and i = 1
[2]
names = [James, Marshall, Matt, Carl];//Matt is now at index 2 and i = 2
[2]
names = [James, Marshall, Carl];//Carl is now at index 3 and i = 3
names = [James, Marshall,]; //for loop ends
Here is a snippet of what your final method may look like:
public void remove_user(String name) {
int location = names.indexOf(name); //assign the int value of name to location
if (names.remove(name)==true) {
for (int i = 0; i < 7; i++) {
names.remove(names.get(location));
}//end if
print(name + " is no longer in the Group.");
}//end method
This is a common problem while using Arraylists and it happens due to the fact that the length (size) of an Arraylist can change. While deleting, the size changes too; so after the first iteration, your code goes haywire. Best advice is either to use Iterator or to loop from the back, I'll recommend the backword loop though because I think it's less complex and it still works fine with numerous elements:
//Let's decrement!
for(int i = size-1; i >= 0; i--){
if (data.get(i).getCaption().contains("_Hardi")){
data.remove(i);
}
}
Still your old code, only looped differently!
I hope this helps...
Merry coding!!!
I'll try to explain this as best I can. I have an ArrayList of String's. I am trying to implement server-side paging for a webapp. I am restricted to the number of items per page (6 in this case) which are read from this ArrayList. The ArrayList is, lets say, the entire catalog, and each page will take a section of it to populate the page. I can get this working just fine when there are enough elements to fill the particular page, its when we hit the end of the ArrayList where there will be less than 6 items remaining for that pages segment. How can I check if the ArrayList is on its last element, or if the next one doesn't exist? I have the following code (in pseudo-ish code):
int enterArrayListAtElement = (numberOfItemsPerPage * (requestedPageNumber - 1));
for (int i = 0; i < numberOfItemsPerPage; i++) {
if (!completeCatalog.get(enterArrayListAtElement + i).isEmpty() {
completeCatalog.get(enterArrayListAtElement + i);
}
}
The if in the code is the problem. Any suggestions will be greatly appreciated.
Thanks.
It sounds like you want:
if (enterArrayListAtElement + i < completeCatalog.size())
That will stop you from trying to fetch values beyond the end of the list.
If that's the case, you may want to change the bounds of the for loop to something like:
int actualCount = Math.min(numberOfItemsPerPage,
completeCatalog.size() - enterArrayListAtElement);
for (int i = 0; i < actualCount; i++) {
// Stuff
}
(You may find this somewhat easier to format if you use shorter names, e.g. firstIndex instead of enterArrayListAtElement and pageSize instead of numberOfItemsPerPage.)
Can't you just get
completeCatalog.size()
and compare it to i? i.e to answer the question "is there an ith element" you say
if (i<completeCatalog.size())
You just need to add a second expression to look whether the end of the list was reached already:
int enterArrayListAtElement = (numberOfItemsPerPage * (requestedPageNumber - 1));
for (int i = 0; i < numberOfItemsPerPage; i++) {
if (enterArrayListAtElement + i < completeCatalog.size() && !completeCatalog.get(enterArrayListAtElement + i).isEmpty() {
completeCatalog.get(enterArrayListAtElement + i);
}
}
An ArrayList has the method of size(), which returns the number of elements within the List.
Therefore, you can use this within the if statement to check you've not went too far.
For example,
if(enterArrayListAtElement + i < completeCatalog.size()) {
...
}