Array List question

[Joseph]

I'm trying to remove a string from an array list but I'm getting an exception. I forgot with one it was. I looked it up and they said I need to iterate it from the array list. But it doesn't seem like its what I want to do with it. Any suggestions?

[Swizzbeat]

Are you modifying it from another thread? ArrayList is not thread safe, but you can set it as so by doing:

ArrayList<String> exmaple = (ArrayList<String>) Collections.synchronizedList(new ArrayList<String>());

[Joseph]

i don't know about threads too much. That's will be the next thing ill learn. But i'm as modify the arraylist. ill try that out later. Ill elt you know how it goes

[lare96]

are you getting a ConcurrentModificationException?

 

if so what Swizzbeat suggested will work although I wouldn't recommend using concurrent collections as they can be slower

 

 

you're probably getting that error because you're trying to do something like this

 

for(Element e : list) {
    if(e == null) {
        continue;
    }
 
    e.function();
    list.remove(e); // <- will throw a ConcurrentModificationException!!
}

you cant modify a list that isnt concurrent while doing this type of loop. use a raw iterator instead like so

 

for(Iterator<Element> iterator = list.iterator(); iterator.hasNext();) {
     Element e = iterator.next();
 
     if(e == null) {
         continue;
     }
 
     e.function();
     iterator.remove(); // <- does the same thing but no exception will be thrown!
}

or like I stated before, you can use a CopyOnWriteArrayList or what the dude above suggested

[Sigma]

are you getting a ConcurrentModificationException?

 

if so what Swizzbeat suggested will work although I wouldn't recommend using concurrent collections as they can be slower

 

 

you're probably getting that error because you're trying to do something like this

for(Element e : list) {
    if(e == null) {
        continue;
    }
 
    e.function();
    list.remove(e); // <- will throw a ConcurrentModificationException!!
}

you cant modify a list that isnt concurrent while doing this type of loop. use a raw iterator instead like so

for(Iterator<Element> iterator = list.iterator(); iterator.hasNext();) {
     Element e = iterator.next();
 
     if(e == null) {
         continue;
     }
 
     e.function();
     iterator.remove(); // <- does the same thing but no exception will be thrown!
}

or like I stated before, you can use a CopyOnWriteArrayList or what the dude above suggested

I have a hunch this is what he's trying to do.

[Joseph]

I still haven't tried it yet