Enum Java Interview Questions

1. What exactly is Java?

Java is a portable, high-level, object-oriented, robust, secure, platform-independent, multi-threaded, high-performance programming language. Developed in June 1991 by James Gosling, also known as Platform.

2. Enum is what?

A Type can be given a list of values using Enum.Consider the model beneath.It specifies a Season enum with four possible values.

enum Season {

        WINTER, SPRING, SUMMER, FALL};

3. How would you look at two Enums?

//Comparing two Enums
        Season season1 = Season.FALL;
        Season season2 = Season.FALL;
        System.out.println(season1 == season2);//true
        System.out.println(season1.equals(season2));//true

Upsides of Enum's can measure up utilizing == or the equivalents capability.

4. Can you use a Switch Statement around an Enum?

The example below shows how we can use a switch around an enum.

public int getExpectedMaxTemperature() {
            switch (this) {
            case WINTER:
                return 5;
            case SPRING:
            case FALL:
                return 10;
            case SUMMER:
                return 20; }  return -1 ;   }

5. The idea of an enum there for a reason?

Enums are lists of constants; using them to define a list of constants is helpful. When the list of results is limited, an enum is useful.

6. Can enum constantsbe declaredstatic and final?

Yes, Enum constants are public, static, and final and can be accessed directly through the enum name.

7. Can I add items by expanding the enum?

No, you can't extend the Enum further in the code. It is defined with the Enum keyword and is only filled with elements, but these elements cannot be added to the program in another way.

8. What are the advantages of using Enums in Java?

• Enums improve security
• Enums can be placed inside or outside a class
• Enum can be  used in switch case just fine
• Enum cannot extend classes
• No Enumeration Targets
• Enum can contain variables, constructors, and methods

9. Can Enums implement interfaces in Java?

Enums can implement interfaces in Java Enums are types, just like classes and interfaces, so that they can implement interfaces. In some cases, this gives you a lot more flexibility to use Enum as a specialized implementation.

10. What does the Enum ordinal() method do?

public enum WeekDay{
  MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY;
}

• The order in which Enum instances are declared within an Enum is returned by the ordinal method. You can declare the days in the order in which they occur.
• A DayOfWeek enumeration. Ordinal places or assigns a 0-based number to each element of the enum. Monday starts at 0 and Tuesday starts at 1. Calling WeekDay.Thursday. Ordinal () returns 3.

11. Give an example of using a switch case with Enum.

In the switch case, an enum can be passed as an argument:the com.java1 package;

public class SwitchEnum {
	enum Color
	{
		RED,GREEN,BLUE
	}
	public static void main(String[] args) {
		
		Color k;
		k = Color.GREEN;
		
		switch(k)
		{
		case RED:
			System.out.println("I am "+k);
			break;
		case GREEN:
			System.out.println("I am "+k);
			break;
		case BLUE:
			System.out.println("I am "+k);
			break;
		
		}	
	}
}

12. Can an Enum instance be created outside an Enum? Then why?

No, Enum instances cannot be created outside Enum bounds because Enums do not have public constructors and cannot be provided by the compiler. Java Enum Interview Questions and Answers for Programmers A public constructor in an Enum has to declare his Enum instance inside the Enum itself because the compiler generates much code in response to his Enum type declaration.

13. What is the difference between ordinal() and CompareTo() in Enum?

This is a continuation of the previous Java enum question. CompareTo() mimics Enum's natural ordering provided by the ordinal() method.

That is, enum constraints are compared in the orderthey are declared. Also, note that enum constants can only be compared to other enum constants of the same type. Enum constants of two different types are compared.

14. How do you iterate over all instances of an enum?

If you look into java, Lang.Enum, you'll find that there is quality() techniques that use various enum constants. All enums are proven to extend java.lang.Enum, so we get this quality() strategy. You can iterate over all enum constants of a particular type. See here for an enum value model in Java that uses values() and foreach circles to highlight enums.