Java

Question 1

Why use Java

Answer 1

It’s a rich api, portable, simple and fast to use.

Question 2

What are the JDK, JRE, and the JVM.

Answer 2

JDK: Within the JRE. It’s the Java Development Kit and it holds the compiler.
JRE: Within the JDK. It’s the Java Runtime Environment. This holds the class library.
JVM: This is the Java Virtual Machine and it is where the code actually runs.

Question 3

What’s a class?

Answer 3

Blueprint of an object which is an instance of a class

Question 4

What ae the access modifiers and what they can access

Answer 4

Public
Private
Protected
Default

Question 5

What are the non access modifiers

Answer 5

Abstract, Final, Transient, and Volatile

Question 6

The types and scopes of variables in Java

Answer 6

Types: Static, Instance and Local
Scope: Class, Block, Instance

Question 7

The data members and their sizes.

Answer 7

Byte - 1
Char - 2
Short - 2
Int - 4
Float - 4
Long - 8
Double - 8 
Boolean - Varies

Question 8

Class members in Java

Answer 8

Fields, Methods, constructors, inner class, interface, block

Question 9

Is Java 100% OOP?

Answer 9

No, because of the 8 primitives

Question 10

Why is the string pool necessary?

Answer 10

Strings are Immutable. The string pool holds all the data for the strings in a place in the heap memory so that whenever you call that string or you create a string with the same value, it won’t create more, it will merely point to that one.