List vs ArrayList vs Dictionary vs Hashtable vs Stack vs Queue? [closed]

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Closed 5 years ago.

We can use any of these (includes List, ArrayList, Dictionary, Hashtable, Stack, Queue) to hold value or hold reference to other objects as a collection.

But, my question is which one is used when?

回答1:

Lists

Lists allow duplicate items, can be accessed by index, and support linear traversal.

• ArrayList - An array-based list that doesn't support generic types. It does not enforce type safety and should generally be avoided.

• List - An array list that supports generic types and enforces type-safety. Since it is non-contiguous, it can grow in size without re-allocating memory for the entire list. This is the more commonly used list collection.

Hashes

Hashes are look-ups in which you give each item in a list a "key" which will be used to retrieve it later. Think of a hash like a table index where you can ask questions like "I'm going to find this object by this string value. Duplicate keys are not allowed.

• HashTable - A basic key-value-pair map that functions like an indexed list.

• Dictionary - A hashtable that supports generic types and enforces type-safety.

Queues

Queues control how items in a list are accessed. You typically push/pop records from a queue in a particular direction (from either the front or back). Not used for random access in the middle.

• Stack - A LIFO (last in, first out) list where you push/pop records on top of each other.

• Queue - A FIFO (first in, first out) list where you push records on top and pop them off the bottom.

回答2:

• List can hold duplicate objects

• ArrayList is just for compatibility with older versions of the framework where IList didn't exist

• Dictionary is used to store pairs of key/value. You cannot have duplicate keys.

• Hashtable is basically a List with no possibility of duplicates (and better performance in some scenarios)

• Stack stores objects in order they were added (through Push()), and when you retrieve an object (through Pop()) it is removed from the stack in a LIFO manner.

• Queue quite similar to a Stack except it is FIFO.

回答3:

Here are some uses for them.

List: If you just want a list and don't care about any duplicates, i.e list of people, shopping list, list of things to do in life.

Queues: If you want to simulate a queue for example, in a hospital you have a queue and also priority queue (in emergency departments). The triage would determine who is in critical condition and needs to be treated.

Another example is a shopping queue, first person in line is 'usually' the first one to checkout.

Stacks: Used in your internal memory to push and pop values as you pass them to functions/methods.

Another interesting use is, in video game inventory method, where you can pick up an item (push) onto the stack, and drop an item (pop) off the stack.

Hash/Dictionary: These are usually seen used in database, for look up and index.

Depending on what you want to simulate, I do agree with the others, it's handy to read up on data-structures. A book helps but the internet also has a wealth of information.

来源：https://stackoverflow.com/questions/11902107/list-vs-arraylist-vs-dictionary-vs-hashtable-vs-stack-vs-queue