Remove objects from an ArrayList based on a given criteria
You can use Collection::removeIf(Predicate filter) (available from Java8 onwards), here is a simple example:
final Collection<Integer> list = new ArrayList<>(Arrays.asList(1, 2));
list.removeIf(value -> value < 2);
System.out.println(list); // outputs "[2]"
When you are removing the element from the same list, the index gets disturbed. Try little differently as below:
for (int i=0; i < pulseArray.size(); i++) {
Pulse p = (Pulse)pulseArray.get(i);
if (p.getCurrent() == null) {
pulseArray.remove(p);
i--;//decrease the counter by one
}
}
You must use an Iterator
to iterate and the remove
function of the iterator (not of the list) :
Iterator<Pulse> iter = pulseArray.iterator();
while (iter.hasNext()) {
Pulse p = iter.next();
if (p.getCurrent()==null) iter.remove();
}
Note that the Iterator#remove function is said to be optionnal but it is implemented by the ArrayList's iterator.
Here's the code of this concrete function from ArrayList.java :
765 public void remove() {
766 if (lastRet < 0)
767 throw new IllegalStateException();
768 checkForComodification();
769
770 try {
771 ArrayList.this.remove(lastRet);
772 cursor = lastRet;
773 lastRet = -1;
774 expectedModCount = modCount;
775 } catch (IndexOutOfBoundsException ex) {
776 throw new ConcurrentModificationException();
777 }
778 }
779
780 final void checkForComodification() {
781 if (modCount != expectedModCount)
782 throw new ConcurrentModificationException();
783 }
784 }
The expectedModCount = modCount;
line is why it won't throw an exception when you use it while iterating.
No need to use iterator. With Java 8 (streaming and filtering capability and lambdas) you can accomplish it using one line. For eg. the required code that does the operation you specified will be :
pulseArray = pulseArray.stream().filter(pulse -> pulse != null).collect(Collectors.toList());