How do you declare an interface variable in Java?

How do you declare an interface variable in Java?

🔔 The variable in an interface is public, static, and final by default. 🔔 If any variable in an interface is defined without public, static, and final keywords then, the compiler automatically adds the same. 🔔 No access modifier is allowed except the public for interface variables.

Can you declare variables in interface?

You can declare variables to be of an interface type, you can declare arguments of methods to accept interface types, and you can even specify that the return type of a method is an interface type.

What is the naming convention for interface in Java?

In Java, interfaces names, generally, should be adjectives. Interfaces should be in the title case with the first letter of each separate word capitalized. In some cases, interfaces can be nouns as well when they present a family of classes e.g. List and Map .

How should you name variables in Java?

For variables, the Java naming convention is to always start with a lowercase letter and then capitalize the first letter of every subsequent word. Variables in Java are not allowed to contain white space, so variables made from compound words are to be written with a lower camel case syntax.

What type of variables can be defined in an interface?

4. What type of variable can be defined in an interface? Explanation: variable defined in an interface is implicitly final and static. They are usually written in capital letters.

Which keyword can be used while declaring variable in interface?

Interface Modifiers The keywords public and abstract can appear as modifiers at the beginning of an interface declaration. In this situation, these modifiers have the following meanings: public. If an interface is declared public, it can be referenced by any class or interface.

Can a interface have variables in Java?

In Java, an interface is an abstract type that contains a collection of methods and constant variables. It is one of the core concepts in Java and is used to achieve abstraction, polymorphism and multiple inheritances.

Can an interface name be used as the type of a variable?

Yes–the variable can refer to any object whose class implements the interface.

Can we have variables in interface Java?

Java Interface also represents the IS-A relationship. Like a class, an interface can have methods and variables, but the methods declared in an interface are by default abstract (only method signature, no body). Interfaces specify what a class must do and not how.

What are the 3 rules for naming variables in Java?

Step 1 − All identifiers should begin with a letter (A to Z or a to z), currency character ($) or an underscore (_). Step 2 − After the first character, identifiers can have any combination of characters. Step 3 − A keyword cannot be used as an identifier.

How do you declare a variable name?

Rules for naming variables:

  1. All variable names must begin with a letter of the alphabet or an. underscore( _ ).
  2. After the first initial letter, variable names can also contain letters and numbers.
  3. Uppercase characters are distinct from lowercase characters.
  4. You cannot use a C++ keyword (reserved word) as a variable name.

Which variable declaration is proper for interface?

To declare an interface, use the interface keyword. It is used to provide total abstraction. That means all the methods in an interface are declared with an empty body and are public and all fields are public, static, and final by default.

Which of the following is the correct declaration of an interface?

An interface is declared by using the interface keyword. It provides total abstraction; means all the methods in an interface are declared with the empty body, and all the fields are public, static and final by default. A class that implements an interface must implement all the methods declared in the interface.

Which keyword is used to declare an interface in Java Mcq?

Explanation: interface keyword is used to define interfaces in Java.

Which type of variable can be defined in an interface?