What are collections
Collection is a Framework which will have set of interfaces and classes which is used to store the data. Collection in general refers to group of data.
Before discussing about Collections, we will discuss about why we are going for collections. In java, collection of elements are stored using Arrays. Click here to read about Arrays in JAVA.
Advantages of Arrays:
compile time checking is done for the element types
It can hold primitive data types and object references
Disadvantages of Arrays:
The size of arrays are fixed
No built in algorithms to sort,search etc...
In order to overcome the disadvantages, we are going to collections.
Collection [ Interface]
1 . Queue [ Interface]
2. List [Interface]
3. Set [ Interface ]
a] SortedSet[ Interface]
b] NavigableSet [ Interface]
Map is a special type of collection, which is used frequently
Map [ Interface]
1. SortedMap [ Interface]
2. ConcurrentMap [ Interface]
Let us see the classes implementing the above collection interfaces.
Classes implementing List Interface
1. LinkedList
2. ArrayList
Old collection classes
3. Vector
4. Stack
Classes implementing set Interface
1. LinkedHashSet - Stores data in insertion order
2. HashSet - Stores data in random order
3. TreeSet - Stores data in sorted order
Classes implementing Map Interface
1. LinkedHashMap -Stores data in insertion order
2. HashMap -Stores data in random order
3. TreeMap -Stores data in sorted order
Collection is a Framework which will have set of interfaces and classes which is used to store the data. Collection in general refers to group of data.
Before discussing about Collections, we will discuss about why we are going for collections. In java, collection of elements are stored using Arrays. Click here to read about Arrays in JAVA.
Advantages of Arrays:
compile time checking is done for the element types
It can hold primitive data types and object references
Disadvantages of Arrays:
The size of arrays are fixed
No built in algorithms to sort,search etc...
In order to overcome the disadvantages, we are going to collections.
Collection [ Interface]
1 . Queue [ Interface]
2. List [Interface]
3. Set [ Interface ]
a] SortedSet[ Interface]
b] NavigableSet [ Interface]
Map is a special type of collection, which is used frequently
Map [ Interface]
1. SortedMap [ Interface]
2. ConcurrentMap [ Interface]
Let us see the classes implementing the above collection interfaces.
Classes implementing List Interface
1. LinkedList
2. ArrayList
Old collection classes
3. Vector
4. Stack
Classes implementing set Interface
1. LinkedHashSet - Stores data in insertion order
2. HashSet - Stores data in random order
3. TreeSet - Stores data in sorted order
Classes implementing Map Interface
1. LinkedHashMap -Stores data in insertion order
2. HashMap -Stores data in random order
3. TreeMap -Stores data in sorted order
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