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Note from Cracking the coding Interview
How to improving Coding skills
These are the questions you actually want to know. Here are a few ideas of questions that are valuable to many candidates:
1. “How much of your day do you spend coding?”
2. “How many meetings do you have every week?”
3. “What is the ratio of testers to developers to product managers? What is the interaction like? How does project planning happen on the team?”


These questions are designed to demonstrate your deep knowledge of programming or technologies.

1.  “I noticed that you use technology X. How do you handle problem Y?” 
2. “Why did the product choose to use the X protocol over the Y protocol? I know it has bene!ts like A, B, C, but many companies choose not to use it because of issue D.

               

Fail fast	fail safe	Age
immediately throw ConcurrentModificationException if a collection is modified while iterating over it	Fail-Safe iterators don’t throw any exceptions if a collection is modified while iterating over it	50
	operate on the clone of the collection, not on the actual collection	94
When collection is structuraly modified (add, remove, update) by its instance, Accepted by iterator's remove method	Doe	80
use modCount	ConcurrentHashMap	80

List list = new ArrayList(Arrays.asList("a","b","c","d","e"));
Iterator i = list.iterator();
while (i.hasNext()) {
//i.remove(); //IllegalStateException
System.out.println(i.next());
i.remove(); // OK

//list.remove("d"); // Always throw concurrent modification exception
//list.add("f"); // Always throw concurrent modification exception
}

h1b good article from nytimes


Use of Logical shift
 right-shift ( >> 1 ) is equivalent to  a /= 2
left shift ( << 1) is equivalent  a=a*2

i	i >> 1	i >> 2	i >> 3
1	0	0	0
2	1	0	0
3	1	0	0
4	2	1	0
5	2	1	0
6	3	1	0
7	3	1	0
8	4	2	1
9	4	2	1
i	i << 1	i << 2	i << 3
1	2	4	8
2	4	8	16
3	6	12	24
4	8	16	32
5	10	20	40
6	12	24	48
7	14	28	56
8	16	32	64
9	18	36	72

Spring Controller is singleton and class level parameters are shared among all the request
for each new request a new thread is created