Java英文面试问答（三）

6. Define JDK, JRE, and JVM?

JDK: It is an abbreviation for Java Development Kit used for compiling, documenting, and packaging Java programs. It includes JRE and development tools.

JRE: Java Runtime Environment or JRE is a runtime environment for Java bytecode execution. It is for making JVM active and effective.

JVM: It is Java Virtual Machine, which is an abstract machine. It sends instructions to the computer's processor to execute for the execution of Java bytecode.

7. What makes Java platform-independent?

Because of its features to run bytecodes on any system, regardless of which platform they are written on.

8. Is Java 100% object-oriented. If not, than why?

No. Java is not 100% object-oriented since it used eight primitive data types. Which are: boolean char, byte, float, int. double, short, and long. And all these are not objects.

9. What are Constructors in Java?

They are a block of codes meant for initializing an object. However, their name should be identical to that of the class. Moreover, when an object is created, it automatically gets called because of not having any return type.

10. What are the types of Constructors?

The constructors are of two types:

1.Default Constructor: This constructor is so named because it is created by default, which means without any inputs from the user. It is also called no argument constructor since it doesn't take any inputs. It takes the default values of the instance variables and is used for creating an object.

2.Parameterized Constructor: It is the constructor that has the quality to initialize the instance variables as per the provided values. It is so called because it takes the arguments.

Java is vast which is why there is no way to guess how many questions would be asked in the interview. It totally depends on the interviewer and the time he or she has to interview you.