Core Java - Interview Questions and Answers for 'Interface' | Search Interview Question

Interview Questions and Answers - Order By Newest

Q61. What is an Interface ?

Ans. The interface is a mechanism to achieve abstraction. Interfaces can have abstract methods and variables. It cannot have a method body.

Sample Code for interface

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Q62. How do you define a functional interface?

Core Java

Ans. Create interface with the only one non-overriding abstract method and annotate it with @FunctionalInterface

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Q63. Can we have interface as a replacement for utility class ?

Core Java

Ans. Yes, With Java 8 we can use Interfaces as collection of utility methods through the use of default methods.

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Q64. Can we declare constructor inside an interface ? Why ?

Core Java

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Q65. Does Java generate .class file for interfaces ?

Core Java

Ans. Yes

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Q66. Which Java version supports Interface Default methods ?

Core Java

Ans. Java 1.8 or Java 8

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Q67. Interface vs Abstraction

Core Java

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Q68. Explain interfaces in Typescript. How is it different compared to other languages ?

TypeScript

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Q69. Which method needs to be implemented if a class is implementing comparable interface ?

Core Java

a. comp

b. compare

c. compareTo

d. compareEquals

Ans.c. compareTo

Q70. If X implements Y and Y extends Z, Which of the following initialization is correct ?

Core Java

a. X x = new Y();

b. X x = new Z();

c. Z z = new Y();

d. Z z = new X();

Ans.d. Z z = new X();

Q71. If class A implements X interface, and Class B implements Y interface, and X is the parent of Y, Which of the following initialization is correct ?

Core Java

a. A a = new B();

b. Y y = new A();

c. X x = new B();

d. Y y = new A();

Ans.c. X x = new B();

Q72. Which of the following is a Marker Interface ?

Core Java

a. Runnable

b. Serializable

c. Cloneable

d. Both Serializable and Cloneable