In many programming languages, including JavaScript, Python, and Java, an array is a structured data type that stores a group of objects (items or values) of the same kind. To create an array, you must declare it first. For example, in Java, you would write the following code to declare an array of integers:

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int[] myArray = new int[4];

This declares an array with 4 elements of type int. You can assign values to each of the elements using the array's index, like this:

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myArray[0] = 40;
myArray[1] = 25;
myArray[2] = 18;
myArray[3] = 33;

In order to format the date time, you will need to use the appropriate date-time library in the programming language you are using. For example, in Java, you can use the java.time library to format date-time objects.

You can use the LocalDateTime.format() method to format the date-time string. By specifying a DateTimeFormatter instance, you can customize your output format.

Java example:

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import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

// Format the current date-time
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd-M-yyyy hh:mm:ss"); 
LocalDateTime localDateTime = LocalDateTime.now();
String dataTimeString = localDateTime.format(formatter);

System.out.println(dateTimeString);

Output: 20-8-2018 11:48:27

Polymorphism is a concept in object-oriented programming (OOP) where an object can take on multiple forms. In other words, the same object can behave differently depending on the context in which it is used. For example, a Vehicle type in OOP can be a Car, a Motorcycle or a Bicycle, depending on which is being referenced. In Java, this is achieved by making a parent object (e.g. Vehicle) with common attributes and methods, and then having sub-types that inherit from the parent object and add specific attributes and methods (e.g. Car, Motorcycle and Bicycle).

In Java, Polymorphism is implemented through the use of Abstract Classes and Interfaces. Abstract Classes give the superclass the ability to define methods that all the subclasses will inherit. Interfaces on the other hand specify the type of objects that can be used by other classes, and provide a set of methods that all classes sharing the interface will have to implement.

Here is an example in Java of how polymorphism can be used:

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public abstract class Vehicle { 
  // Attributes and Methods common to all Vehicles 
} 

public class Car extends Vehicle { 
  // Unique attributes and methods applicable to only Cars 
} 

public class Motorcycle extends Vehicle { 
  // Unique attributes and methods applicable to only Motorcycles 
}

public class Bicycle extends Vehicle { 
  // Unique attributes and methods applicable to only Bicycles 
} 

The Vehicle class here defines methods and attributes that will be common to all types of vehicles, while the Car, Motorcycle and Bicycle subclasses each create specific implementations of those attributes and methods.

You can read more about Polymorphism here: https://www.geeksforgeeks.org/polymorphism-in-java/

Java is a general-purpose, object-oriented programming language developed by Sun Microsystems (which is now part of Oracle Corporation) for developing applications for desktop and small-footprint devices. It is the most popular programming language for Android smartphone applications and is among the most favored for edge device and internet of things development. Java is a class-based, concurrent, strongly typed language with an emphasis on object-oriented programming. It has been written using C and C++ syntax, and its syntax is similar to those languages. Java can be used to create highly executable applications and applets for use in a network such as the internet, as well as in various embedded devices. More information on Java can be found here: https://www.java.com/en/.