Introduction to Java Collection Generics
Java collection generics is used to add a way in the specified concrete types, and it’s the general purpose of classes and methods that operated object for performing and abstracting it so that it will look at some more typically used in the collections. The java generics with other classes rather than the collection classes is the easiest way to show the basics of Java generics, but it’s the quickest way to show the basics of Java generics with referencing and de-referencing its using settings for the generic type of a Collection and other classes like HashSet, HashMap etc.
Java Collection Generics Overview
The java generics are more important for creating the sort and its method also it first performed the cast and then it will use the datatype arrays like Integer, String, char or any other array that supports ordering in the user datas. Generic methods and generic classes are used in Java programmers to allow and declare a group of related methods with specified types in a single method declaration using the class declaration, respectively. Generics classes are also used to provide a type of safety at specified build time and allowing programmers to catch the erroneous types with particular transformation. Additionally, we could construct a generic method for sorting an array of objects using the Java Generic idea, rather than the use the generic method using Integer arrays, Double arrays, String arrays, and other data types filter so on to sort the array contents.
Uses of generic collections in Java
In java programming language the generic collections are most important and it allows the object creation of the single type using the Type safety. If the type is Type safety it means that the compiler will validate the specific types while using the compilation time and even though it will throw the error if the type value is not supported. If suppose we used Type Casting means its no need for casting the types like String, Integer, double etc. But mostly the generics are not needed for this operation while we performed in the application. Before generics we can store any type of objects with the specified collections that may be any of the types like both generic and non-generic now the generics will enforce the java coder to perform the object creation and its operations like storing and retrieving the values from backend to front end. If the generic collections are disabled, then the typecasting should achieve it and there is no usage for the type-casting when it is used in the generics. The generic collections have some default methods to achieve the functionality that takes the array of objects and the collections for putting and getting the data’s from all the objects in the array collection. As in MapK,V>, the generic Map interface (and map implementations) are defined with two parameterized types. Each key’s type is K, and a key’s associated value’s type is V. So, we’d declare MapString,Integer> to store a map indicating how often each word appears in a text file. We would create MapString,ListInteger>> if we needed a map defining the lines on which each word appears in a text file. It’s worth noting that we can combine (or layer) generic type instantiations.
Advantages of Java Generics
This has been a rapid tour of Java generics’ most important features. “Most crucial” in this context refers to “more important when compare to all other language programmers who use generics.” But the main goal is to have enough knowledge about generics to be able to utilise generics written by other programmes. To put it another way, we need to understand generics well enough to get the compiler to accept our programme without warnings or errors. That is, if Java accepts our programme, the generic mechanism should assure its type safety.
Type-safety is one of the advantages and it can only store one type of object. It does not allow for the storage of other items. We can store any type of object without Generics.
It is not necessary to use type casting when the object does not need to be typecast.
Before that we can use Generics, we must first typecast the values and then it should perform Generics.
Compile-Time Checking ensures that an issue does not arise at runtime. It is considerably better to handle the problem at compile time than at runtime, according to the excellent programming approach.
Example #1
import java.util.*;
class TestGenerics1{
public static void main(String args[]){
ArrayList<String> lst=new ArrayList<String>();
lst.add("January is the first month ");
lst.add("February is the second month");
lst.add("March is the third month");
lst.add("April is the fourth month");
lst.add("May is the fifth month");
lst.add("June is the sixth month ");
lst.add("July is the seventh month");
lst.add("August is the eigth month");
lst.add("September is the ninth month");
lst.add("October is the tenth month");
lst.add("November is the eleventh month");
lst.add("December is the twelth month");
String str=lst.get(7);
System.out.println("Welcome To My Domain its the first example: "+str);
Iterator<String> iterators=lst.iterator();
while(iterators.hasNext()){
System.out.println(iterators.next());
}
}
}Output:
In the above example, we used Array List collection classes in the generics. With the help of add() method we can add n number of input values and get() method to retrieve the values.
Example #2
import java.util.*;
class TestGenerics1{
public static void main(String args[]){
Map<Integer,String> first=new HashMap<Integer,String>();
first.put(1,"Tv is the electronic device");
first.put(2,"Laptop is the electronic device");
first.put(3,"Computer is the electronic device");
first.put(4,"Mobile is the electronic device");
first.put(5,"Tablet is the electronic device");
Set<Map.Entry<Integer,String>> second=first.entrySet();
Iterator<Map.Entry<Integer,String>> iterators=second.iterator();
while(iterators.hasNext()){
Map.Entry<Integer, String>result=iterators.next();
System.out.println(result.getKey()+" "+result.getValue());
}
}}Output:
In the above example we used generic collections by using the Map interface. It contains some default and customized methods for achieving the operations. With the help of iterators, the values are listed on the loop.
Conclusion
Generally, it makes the job of the programmer easier and less error-prone when we use Java Generics its a powerful addition to the Java language. It provides any type of correctness at compile time and, more crucially, it’s to implement generic algorithms without adding overhead to the java programmers when compared to the other language.
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This is a guide to Java Collection Generics. Here we discuss the Introduction, overview, uses, advantages, examples with code implementation for better understanding. You may also have a look at the following articles to learn more –
