got to delete an element from a collection

[shiniskumar]

Ive got a collection with values
Object[0]= hashmap(k,v)
Object[1]= hashmap(k,v)
Object[2]= hashmap(k,v)
Object[3]= hashmap(k,v)
Object[4]= hashmap(k,v)

i terated this collection and deleted object[1]. then when i iterate again i get the following exception.
java.util.ConcurrentModificationException

i want to delete elements till Object[3].
how do i do this
please help

[r035198x]

Ive got a collection with values
Object[0]= hashmap(k,v)
Object[1]= hashmap(k,v)
Object[2]= hashmap(k,v)
Object[3]= hashmap(k,v)
Object[4]= hashmap(k,v)

i terated this collection and deleted object[1]. then when i iterate again i get the following exception.
java.util.ConcurrentModificationException

i want to delete elements till Object[3].
how do i do this
please help

How did you delete? Post your code for the deleting part

[shiniskumar]

How did you delete? Post your code for the deleting part

for (Iterator iter = voucherTransactionCols.iterator(); iter.hasNext();) {
Object object = (Object) iter.next();
HashMap campusModel = (HashMap) object;

voucherTransactionCols.remove(campusModel);
}

Now i can delete the elements but when i delete Object[3] , the element Object[4] moves to the third position . so i cant delete the last elenment in the collection.

[dmjpro]

see this code carefully .....

Collection c = some code here;

Label:
for(int i=0;i<c.size();i++)
if(condition)
{
c.remove(c.get(i));
continue Label;
}

try this code ..........
all the best

[shiniskumar]

see this code carefully .....

Collection c = some code here;

Label:
for(int i=0;i<c.size();i++)
if(condition)
{
c.remove(c.get(i));
continue Label;
}

try this code ..........
all the best

i cannot get the method c.get(i);

[dmjpro]

sorry ..... i just use general convention .....
now i use according to ur code ......

label:
for (Iterator iter = voucherTransactionCols.iterator(); iter.hasNext() {
Object object = (Object) iter.next();
HashMap campusModel = (HashMap) object;

voucherTransactionCols.remove(campusModel);
continue label;
}

try this code ...... all the best ....
i think u understood my logic

[shiniskumar]

sorry ..... i just use general convention .....
now i use according to ur code ......

label:
for (Iterator iter = voucherTransactionCols.iterator(); iter.hasNext() {
Object object = (Object) iter.next();
HashMap campusModel = (HashMap) object;

voucherTransactionCols.remove(campusModel);
continue label;
}

try this code ...... all the best ....
i think u understood my logic

now im getting java.util.ConcurrentModificationException after deleting the first element and going for the next iteration.
wat to do

[dmjpro]

wait plzzzz ... i m trying to solve it ......

[dmjpro]

it is because of removing and iterating concurrently...

so if u post ur code ...... then i think i will give u some hope....


thanxxxxx

[shiniskumar]

it is because of removing and iterating concurrently...

so if u post ur code ...... then i think i will give u some hope....


thanxxxxx

hey i got it
this is my code
label:
for (Iterator iter = voucherTransactionCols.iterator(); iter.hasNext();) {
Object object = (Object) iter.next();
HashMap campusModel = (HashMap) object;
iter.remove();
continue label;
}

}

}

Use the iterator to remove....... instead of coll.remove()

Thanks a lot

[r035198x]

Here is a hint from the docs


"The iterators returned by all of this class's "collection view methods" are fail-fast: if the map is structurally modified at any time after the iterator is created, in any way except through the iterator's own remove or add methods, the iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future"

[r035198x]

hey i got it
this is my code
label:
for (Iterator iter = voucherTransactionCols.iterator(); iter.hasNext();) {
Object object = (Object) iter.next();
HashMap campusModel = (HashMap) object;
iter.remove();
continue label;
}

}

}

Use the iterator to remove....... instead of coll.remove()

Thanks a lot

And it doesn't look like you'd seen my hint too. Very good work.