foreach - Java list's .remove method works only for second last object inside for each loop -

i seeing weird behavior.

    list<string> li = new arraylist<>();     li.add("a");     li.add("b");     li.add("c");     li.add("d");     li.add("e");     for(string str:li){         if(str.equalsignorecase("d")){             li.remove(str);     //removing second last in list works fine         }     } 

but if try remove other second last in list, concurrentmodificationexception. came attention while reading "oracle certified associate java se 7 programmer study guide 2012" incorrectly assumes .remove() works example of removing second last in list.

in list, adding or removing considered modification. in case have made 5 modifications(additions).

‘for each’ loop works follows,

1.it gets iterator. 2.checks hasnext(). 

public boolean hasnext()  {       return cursor != size(); // cursor 0 initially. } 

3.if true, gets next element using next().

public e next()  {         checkforcomodification();         try {         e next = get(cursor);         lastret = cursor++;         return next;         } catch (indexoutofboundsexception e) {         checkforcomodification();         throw new nosuchelementexception();         } }  final void checkforcomodification()  {     // modcount = expectedmodcount (our case 5)         if (modcount != expectedmodcount)         throw new concurrentmodificationexception(); } 

repeats steps 2 , 3 till hasnext() returns false.

in case if remove element list , it’s size gets reduced , modcount increased.

if remove element while iterating, modcount != expectedmodcount satisfied , concurrentmodificationexception thrown.

but removal of second last object weird. lets see how works in case.

initially,

cursor = 0 size = 5 --> hasnext() succeeds , next() succeeds without exception.
cursor = 1 size = 5 --> hasnext() succeeds , next() succeeds without exception.
cursor = 2 size = 5 --> hasnext() succeeds , next() succeeds without exception.
cursor = 3 size = 5 --> hasnext() succeeds , next() succeeds without exception.

in case remove ‘d’ , size gets reduced 4.

cursor = 4 size = 4 --> hasnext() not succeed , next() skipped.

in other cases, concurrentmodificationexception thrown modcount != expectedmodcount.

in case, check not take place.

if try print element while iterating, 4 entries printed. last element skipped.

hope made clear.