Java Interview Questions

1Q) What is java.? A)     Java is an Object Oriented programming (OOPs) language used to develop platform independent applications. Like Web applications & windows Applications. Q) what are the main features of java? A) The main features of java are Platform Independent Object oriented Robust and secure Type safe High Performance. Compiled and Interpreted Q) What is the Java Virtual Machine (JVM)? A) The Java...

1Q) What is java.?

A)     Java is an Object Oriented programming (OOPs) language used to develop platform independent applications. Like Web applications & windows Applications.

Q) what are the main features of java?

A) The main features of java are

Platform Independent

Object oriented

Robust and secure

Type safe

High Performance.

Compiled and Interpreted

Q) What is the Java Virtual Machine (JVM)?

A) The Java Virtual Machine is software that can be ported onto various hardware-based platforms.

Q) Is null a keyword?

A)No, null is not a keyword, it is a value.

Q) which containers use a border Layout as their default layout?

A) window, Frame and Dialog classes use a BorderLayout as their default layout.

Q) How are Observer and Observable used?

A) If a class which extends java.util.Observable that class Objects maintain a list of observers. When an Observable object is updated it invokes the update() method of each of its observers to notify the observers that it has changed state. The java.util.Observer interface is implemented by objects that observe Observable objects.

Q) Can a double value be cast to a byte?

A) Yes, a double value can be cast to a byte.

Q) What is synchronization and why is it important?

A) Synchronization is the process to control the access of multiple threads to shared resources. We will use 'synchornized' keyword to perform synchronization. Without synchronization, it is possible for one thread to modify a shared object while another thread is in the process of using or updating that object's value. This often leads to significant errors.

Q) Is sizeof a keyword?

A) sizeof is an operator, it is not a keyword.

Q) what is a transient variable?

A) A Transient variable is a variable that cannot be serialized. (or) A Variable that wont be allowed for a object to be serialization. So that say that the value always be defaulted after the deserialiastion .

Q) What is the Locale class?

A) The java.util.Locale class is used to represent a particular geographic, political, or cultural region.

Q) Can an unreachable object become reachable again?

A) Yes, an unreachable object may become reachable again. This can happen when the object's finalize() method is invoked and the object performs an operation which causes it to become accessible to reachable objects.