Java Google

Core Java


                               public final class String extends Object
                               implements Serializable, Comparable<String>, CharSequence

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Collections

Design Patterns

What is the difference between JDK, JVM and JRE?

What is the difference between java 6 and java 8?

What are the different methods present in Object class?

What are OOPS concepts? Explain each in brief

Can we have super and this?

String class extends which class?

How do we achieve abstraction and encapsulation in our programming?

What are different types of polymorphism? Explain each of them?

What is the difference between overriding and overloading?

Can one among two overloaded classes throw exceptions and the second won't? If yes Can we say that as overloading?

Rules of function overriding?

Can we have different\reduced access modifiers for overloaded methods?

Difference between Static and Dynamic binding in Java?

What is meant by the static keyword?

Can we override static functions? If yes then how if no then why not?

What is the difference between interface and abstract class? If abstract class provides the same functionality as interface (means in abstract class contains abstract methods as interface) so why do we need interfaces?

Can we have a static/final interface? If not then why?

What is the marker interface? Give example?

What will happen if we extend an abstract class and not implement an abstract method in it? Is there any way by which we can use abstract class by not overriding its methods?

What is Serialization? How do we achieve Serialization in Java?

What is the advantages of version ID in Serialization?

What can we do if we don't want to make some data members non-Serializable?

What is the difference between transient and volatile?

What is the difference between String and StringBuffer class?

What is the difference between StringBuffer and StringBuilder?

How can you make a mutable object immutable?

What is the need of overriding equals and hashCode methods?

What is the difference between == and equals ()?

What difference does it make when we create String like String str1=”someValue” and String str1=new String(“someValue”);

Why String is Immutable?

Why do we have stringPool? and what are the changes for StringPool in Java8

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What is the contract between hashcode and equals?

What is a Singleton Pattern? Implement code for it? What will happen in case of cloning, reflection, serialisation.