10 Example of String in Java

1. String IndexOf Example
2. String SubString Example
3. String Matches Example
4. String Length Example
5. String Empty Check Example

How to replace characters in String

How to remove whitespace from String in Java

How to find length of String in Java

How to check if String is Empty in Java

How to create SubString from String in Java

How to Split String in Java

How to check if String contais a word

How to

arraylist string example in java

java object string example

java string split example

java string to inputstream example

java string to int example

java string length example

java string to double example

java switch string example

10 points about synchronized in Java

1. Synchronized can only be applied to methods and code block, you can not make a variable, a class or an interface synchronized in Java.

2. When a thread enters a synchronized block or method, it acquire lock on the object method has been called. Similarly when thread exits the block, both normally or abruptly due to any error, it relinquish the lock.

3. Synchronized keyword not only provide mutual exclusion, but also provides visibility guarantee. Memory barriers are updated when thread enter or exits synchronized block or method. 

10 points about Exception in Java

1. There are two kinds of exception in Java, checked and unchecked exception. Any exception, which is subclass of java.lang.Exception but not inherited from java.lang.RuntimeException is known as checked Exception. On the other hand those inherited from RuntimeException are called unchecked exception.

2. Checked exceptions follow special symanatic rules in Java, they are literally checked by compiler during compile time.

3. All Exception are inherited from Throwable class.

4. Though Error are not inherited from RuntimeException they are also unchecked.

Why Constructor Injection is better than Setter Injection

There is no doubt that dependency injection is good, and offer several benefits. When it comes to inject dependency, there are two main ways, by using constructor and by using setter methods.


Constructor injection makes dependencies obvious
enforces order of initialization
makes wiring easy
supports testable code
more readable
enforce completeness


CreditCardProcessor ccp = new CreditCardProcessor();

OfflineQueue oq = new OfflineQueue()


Database db = new Database();

IS-A vs HAS-A Relationship Example in Java

IS-A means two classes are part of same inheritance hierarchy, while HAS-A means two classes are not part of same inheritance hierarchy but class A is composed using class B and uses it to provide certain functionality. 

Java Interface and Abstract class Interview Questions

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What is Abstract class?
What is interface?
Difference between Abstract class and inteface?
Can we make a class abstract without abstract method?
Can we make a class final and abstract?
Can we declare constructor in abstract class in Java?
Can an interface extend more than one interface in Java?
Can a class extend more than one class in Java?

Can we have non abstract method inside interface?
What is default method of Java 8?

Difference between SOAP and REST Style Web Service in Java

SOAP and REST are two ways to create web services in Java world, here are couple of key differences between REST and SOAP in Java

Top 50 Core Java Interview Questions with Answers

1)  How Java achieves platform independence? (answer)



2)  What is ClassLoader in Java? (answer)



3)  Write a Java program to check if a number is Even or Odd? (answer)



4)  Difference between ArrayList and HashSet in Java? (answer)



5)  What is double checked locking in Singleton? (answer)



6)  How do you create thread-safe Singleton in Java? (answer)



7)  When to use volatile variable in Java? (answer)



8)  When to use a transient variable in Java? (answer)



9)  Difference between transient and volatile variable in Java? (answer)



10) Difference between Serializable and Externalizable in Java? (answer)



11) Can we override a private method in Java? (answer)



12) Difference between Hashtable and HashMap in Java? (answer)



13) Difference between List and Set in Java? (answer)



14) Difference between ArrayList and Vector in Java



15) Difference between Hashtable and ConcurrentHashMap in Java? (answer)



16) How does ConcurrentHashMap achieve scalability? (answer)



17) Which two methods you will override for an Object to be used as Key in HashMap? (answer)



18) Difference between wait and sleep in Java? (answer)



19) Difference between notify and notifyAll in Java? (answer)



20) Why you override hashcode, along with equals() in Java? (answer)



21) What is load factor of HashMap means? (answer)



22) Difference between ArrayList and LinkedList in Java? (answer)



23) Difference between CountDownLatch and CyclicBarrier in Java? (answer)



24) When do you use Runnable vs Thread in Java? (answer)



25) What is the meaning of Enum being type-safe in Java? (answer)



26) How does Autoboxing of Integer work in Java? (answer)



27) Difference between PATH and Classpath in Java? (answer)



28) Difference between method overloading and overriding in Java? (answer)



29) How do you prevent a class from being sub-classed in Java? (answer)



30) How do you restrict your class from being used by your client? (answer)



31) Difference between StringBuilder and StringBuffer in Java? (answer)



32) Difference between Polymorphism and Inheritance in Java? (answer)



33) Can we override static method in Java? (answer)



34) Can we access private method in Java? (answer)



35) Difference between interface and abstract class in Java? (answer)



36) Difference between DOM and SAX parser in Java? (answer)



37) Difference between throw and throws keyword in Java? (answer)



38) Difference between fail-safe and fail-fast iterators in Java? (answer)



39) Difference between Iterator and Enumeration in Java? (answer)



40) What is identity HashMap in Java? (answer)



41) What is String pool in Java? (answer)



42) Can a Serializable class contain a non serializable field in Java? (answer)



43) Difference between this and super in Java? (answer)



44) Difference between Comparator and Comparable in Java? (answer)



45) Difference between java.util.Date and java.sql.Date in Java? (answer)



46) Why wait and notify method are declared in Object class in Java? (answer)



47) Why Java doesn't support multiple inheritances? (answer)



48) Difference between checked and unchecked Exception in Java? (answer)



49) Difference between Error and Exception in Java? (answer)



50) Difference between race condition and deadlock in Java? (answer)