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What is the benefit of using a generic class like Genclass < T >?
What is the benefit of using a generic class like Genclass < T >?
Type safety and flexibility
What is the primary purpose of using generics in Java?
What is the primary purpose of using generics in Java?
Code reusability
What would happen if we uncomment the line m.add("vivek"); in the First class?
What would happen if we uncomment the line m.add("vivek"); in the First class?
Compile-time error
What is the purpose of the Display method in the First class?
What is the purpose of the Display method in the First class?
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What is the advantage of using a generic method like Display?
What is the advantage of using a generic method like Display?
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What is the output of the main method in the First class?
What is the output of the main method in the First class?
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Why is generics important in Java?
Why is generics important in Java?
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What is the purpose of the type parameter E in the Display method?
What is the purpose of the type parameter E in the Display method?
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Can we use a generic method like Display with an array of objects?
Can we use a generic method like Display with an array of objects?
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What is the benefit of using generics in a method like Display?
What is the benefit of using generics in a method like Display?
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Study Notes
Fixed Size and Its Limitations
- A fixed size has limitations, such as storing only homogeneous data and having no underlying data structures or built-in methods.
- These limitations can be overcome by using collections.
Java Collection
- Definition: A Java collection is a group of individual objects represented as a single unit.
- Framework: Java Collection provides an architecture to store and manipulate groups of objects.
- Advantages:
- Variable size or dynamic size
- Can store homogeneous and heterogeneous data
- Underlying data structures available, providing built-in methods
Collection Framework Hierarchy
- Key interfaces:
- Collection: The root of the collection hierarchy
- Set: A collection that cannot contain duplicate elements
- List: An ordered collection that can contain duplicate elements
- Queue: A collection used to hold multiple elements prior to processing
- Classes:
- ArrayList
- Vector
- LinkedList
- PriorityQueue
- HashSet
- LinkedHashSet
- TreeSet
Type Parameters
- Naming conventions for type parameters:
- T: Type
- E: Element
- K: Key
- N: Number
- V: Value
- Example: Using E to denote the element
Generic Method
- Definition: A generic method that can accept any type of arguments
- Scope: Limited to the method where it is declared
- Allows static and non-static methods
- Example: Printing array elements using a generic method
Generic Class with Multiple Parameters
- Definition: A generic class that can contain more than one parameter
- Syntax: ``
- Example: Creating a generic class with two parameters
Methods in Java Map Interface
- clear(): Clears and removes all elements from a specified map collection
- containsKey(Object): Checks if a particular key is mapped in the map
- containsValue(Object): Checks if a particular value is mapped by any of the keys in the map
- get(Key): Retrieves the value mapped by a particular key
- hashCode(): Generates a hashCode for the given map
- isEmpty(): Checks if a map is having any entry for key and value pairs
- put(Object, Object): Associates the specified value with the specified key in the map
- putAll(Map): Copies all mappings from the specified map to this map
- remove(Object): Removes the mapping for a key from this map
- size(): Returns the number of key-value pairs in the map
Wildcard
- Definition: A special character (?) used to represent an unknown type parameter
- Types of wildcards:
- Upper Bounded Wildcard (?extends T): Specifies that the wildcard can be substituted with any type that is a subtype of T
- Lower Bounded Wildcard (?super T): Specifies that the wildcard can be substituted with any type that is a supertype of T
Example Programs
- Example 1: Generic class
- Example 2: Generic method (using foreach loop to traverse elements)
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Description
This quiz covers the basics of collections in Java programming, including fixed size, homogeneous data, and overcoming limitations with collections.
