what is the difference between list set and map in java?
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The main difference between List and Set interface in Java is that List allows duplicates while Set doesn't allow duplicates. All implementation of Set honor this contract. While a Map holds two objects per Entry e.g. a key and a value and It may contain duplicate values but keys are always unique.
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ArrayList is the collections of different types data whereas List<> is the collection of similar type of its own depedencties. ArrayList are not type safe whereas List<T> are type safe.
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The each method is meant to be an immutable iterator, where as the map method can be used as an iterator, but is really meant to manipulate the supplied array and return a new array. Another important thing to note is that the each function returns the original array while the map function returns a new array.
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Differences: The difference is set is used to store only keys while map is used to store key value pairs. For example consider in the problem of printing sorted distinct elements, we use set as there is value needed for a key.
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A list is an ordered collection of elements that are distinguished by their indices. ... Keys and values can be any data type—primitive types, collections, sObjects, user-defined types, and built-in Apex types. A set is an unordered collection of elements that do not contain any duplicates.
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An array is basic functionality provided by Java. ArrayList is part of collection framework in Java. Therefore array members are accessed using [], while ArrayList has a set of methods to access elements and modify them. Array is a fixed size data structure while ArrayList is not.
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Lists and tuples are standard Python data types that store values in a sequence. Sets are another standard Python data type that also store values. The major difference is that sets, unlike lists or tuples, cannot have multiple occurrences of the same element and store unordered values.
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A Set is a generic set of values with no duplicate elements. A TreeSet is a set where the elements are sorted. A HashSet is a set where the elements are not sorted or ordered. It is faster than a TreeSet.
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In Python, only sets are directly implemented. We can emulate osets with regular dict keys (3.7+). Replicates are removed, insertion-order is preserved. Set-like operations on dict keys.
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Map takes all objects in a list and allows you to apply a function to it whereas Filter takes all objects in a list and runs that through a function to create a new list with all objects that return True in that function.
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Python map() function is used to apply a function on all the elements of specified iterable and return map object. Python map object is an iterator, so we can iterate over its elements. We can also convert map object to sequence objects such as list, tuple etc. using their factory functions.
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The main difference between lists and tuples is the fact that lists are mutable whereas tuples are immutable. ... A mutable data type means that a python object of this type can be modified.
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List is an ordered sequence of elements whereas Set is a distinct list of elements which is unordered. 1) Set does not allow duplicates. List allows duplicate. Based on the implementation of Set, It also maintains the insertion Order .
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The main difference is that a Map, requires that all entries(value & key pair) have a unique key. ... A Dictionary allows for multiple entries to be linked to the same key.
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In fact, all collection classes (except Vector and Hashtable) in the java. util package are not thread-safe. ... That's why the new collections (List, Set, Map, etc) provide no concurrency control at all to provide maximum performance in single-threaded applications.
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HashMaps use an array in the background. Each element in the array is another data structure (usually a linked list or binary search tree). The HashMap uses a function on the key to determine where to place the key's value in the array.
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Map- A map cannot contain duplicate keys. Each key can map to at most one value. Collection and Map both are interfaces in java. util package but Collection is used to store objects and Map is used to store the objects for (key,value) based manner.