Java Interview Questions:

https://www.google.com/#q=java+interview+questions

https://www.google.com/#q=spring+interview+questions

https://www.google.com/#q=jsf+interview+questions

https://www.google.com/#q=database+interview+questions

http://java.dzone.com/articles/java-interview-questsions

http://java.dzone.com/articles/java-interview-questions

http://www.bullraider.com/java/spring3/tutorials/spring-ioc-tutorials/types-of-injections

http://www.bullraider.com/java/spring3/tutorials/spring-ioc-tutorials/injecting-simple-java-type

http://www.mkyong.com/spring/spring-dependency-injection-di/

http://jelastic.com/docs/jelastic-db-hibernate

http://www.youtube.com/watch?v=ea5onQBXzS8

http://www.youtube.com/watch?v=vhYK3pDUijk

http://www.differencebetween.com/difference-between-soa-and-vs-web-services/

http://www.javaworld.com/javaworld/jw-06-2005/jw-0613-soa.html

http://www.differencebetween.com/difference-between-jvm-and-vs-jre/

http://www.differencebetween.com/difference-between-java5-and-vs-java6/

http://docs.oracle.com/javase/tutorial/java/data/autoboxing.html

classloader -  ClassNotFoundException - ClassCastException - LinkageError

Many J2EE application servers have a hot deployment capability,

where we can reload an application with a new version of class

definition, without bringing the server VM down. Such application

servers make use of custom class loaders.

http://www.javalobby.org/java/forums/t18345.html

http://stackoverflow.com/questions/2424604/what-is-a-java-classloader

http://en.wikipedia.org/wiki/Java_Classloader

http://stackoverflow.com/questions/3792745/resolving-class-name-clashes-in-java

http://stackoverflow.com/questions/6105124/java-classpath-classloading-multiple-versions-of-the-same-jar-project

http://stackoverflow.com/questions/244482/how-to-deal-with-linkageerrors-in-java

http://www.javaworld.com/jw-10-1996/jw-10-indepth.html

http://www.techjava.de/topics/2008/01/java-class-loading/

http://www.onjava.com/pub/a/onjava/2005/01/26/classloading.html

Dynamic Proxy - Reflection: (Spring AOP uses it extensively)

http://stackoverflow.com/questions/3291637/alternatives-to-java-lang-reflect-proxy-for-creating-proxies-of-abstract-classes

http://www.javacodegeeks.com/2012/08/creating-java-dynamic-proxy.html

http://www.javacodegeeks.com/2013/04/understanding-dynamic-proxy-spring-aop-basics.html

http://www.techavalanche.com/2011/08/24/understanding-java-dynamic-proxy/

Singleton and Threads:

http://geekswithblogs.net/akraus1/archive/2006/09/10/90803.aspx

http://stackoverflow.com/questions/7790185/singleton-lazy-vs-eager-instantiation

http://stackoverflow.com/questions/11921878/2-regarding-singleton-pattern-eager-initialization-and-synchronization

http://stackoverflow.com/questions/2912281/thread-safety-in-singleton?rq=1

http://en.wikipedia.org/wiki/Initialization_on_demand_holder_idiom

Java 7 Release Notes - Enhancements:

http://www.oracle.com/technetwork/java/javase/jdk7-relnotes-418459.html

Whats New in Java EE 6:

http://www.oracle.com/technetwork/articles/javaee/javaee6overview-141808.html

web 2.0 vs web 3.0

http://cdol.lacoe.edu/blog/web-3-0-vs-web-2-0/

servlet 2.5 vs 3.0

http://stackoverflow.com/questions/1638865/what-are-the-differences-between-servlet-2-5-and-3

Async Servlet/Webservices:

http://cxf.apache.org/docs/developing-a-consumer.html

http://en.wikipedia.org/wiki/Test-driven_development

http://www.differencebetween.com/difference-between-extreme-programming-and-vs-scrum/

http://www.differencebetween.com/difference-between-agile-and-vs-scrum/

http://stackoverflow.com/questions/13772827/difference-between-static-and-final

http://www.differencebetween.com/difference-between-static-and-vs-non-static-method/

http://stackoverflow.com/questions/3903537/i-want-to-know-the-difference-between-static-method-and-non-static-method

Class Loading:

http://stackoverflow.com/questions/2320404/creating-classes-dynamically-with-java

http://viralpatel.net/blogs/java-dynamic-class-loading-java-reflection-api/

http://cglib.sourceforge.net/

http://asm.ow2.org/

http://www.csg.ci.i.u-tokyo.ac.jp/~chiba/javassist/

http://commons.apache.org/proper/commons-bcel/

http://groovy.codehaus.org/Dynamic+Groovy

http://stackoverflow.com/questions/13487765/how-instanceof-will-work-on-an-interface

http://www.differencebetween.com/difference-between-exception-and-vs-error/

http://www.differencebetween.com/difference-between-object-and-vs-instance/

http://www.differencebetween.com/difference-between-abstract-class-and-vs-concrete-class/

http://www.differencebetween.com/difference-between-abstract-class-and-vs-interface/

http://www.differencebetween.com/difference-between-applets-and-vs-servlets/

http://www.differencebetween.com/difference-between-coupling-and-vs-cohesion/

loose coupling and strong cohesion provides the best software

http://www.differencebetween.com/difference-between-enumeration-and-vs-iterator/

http://www.differencebetween.com/difference-between-encapsulation-and-vs-abstraction/

http://www.differencebetween.com/difference-between-implements-and-vs-extends/

http://www.differencebetween.com/difference-between-compiler-and-vs-interpreter/

JSON - Jacson - Conversion:

http://jackson.codehaus.org/

https://github.com/FasterXML/jackson

http://www.mkyong.com/java/how-to-convert-java-object-to-from-json-jackson/

http://jettison.codehaus.org/

http://cxf.apache.org/docs/jax-rs-data-bindings.html

http://www.mkyong.com/webservices/jax-rs/json-example-with-jersey-jackson/

https://jersey.java.net/

Jersey framework uses Jackson or Jettison libraries for JSON unmarshalling/marshalling

Recommendation as far as I know is to use Jackson; Jettison support is older.

http://www.differencebetween.com/difference-between-authentication-and-vs-authorisation/

Web Services - Contract first or Code First:

http://docs.spring.io/spring-ws/sites/1.5/reference/html/why-contract-first.html#d0e321

http://stackoverflow.com/questions/763827/which-is-the-better-approach-to-web-services-contract-first-or-contract-last

http://stackoverflow.com/questions/2000284/contract-last-web-services

http://stackoverflow.com/questions/1898989/what-do-contract-first-and-contract-last-mean

http://www.beingjavaguys.com/2013/04/what-are-web-services-in-spring.html

http://docs.spring.io/spring-ws/site/reference/html/tutorial.html

Web service with Spring-WS and CXF:

http://blog.jeshurun.ca/technology/jax-ws-web-services-with-spring-and-cxf

JAX-RS implementations:

Jersey

CXF

JAXB and JSON:

jettison

jackson

Apache cXF with Jettison or Jackson:

http://www.javatips.net/blog/2012/02/cxf-restful-tutorial

http://www.javatips.net/blog/2012/02/cxf-restful-client

http://www.javatips.net/blog/2012/07/apache-cxf-with-jackson

Spring Batch:

http://java.dzone.com/news/spring-batch-hello-world-1

Enterprise Application Integration (EAI)

Enterprise Integration Patterns (EIP)

Enterprise Service Bus (ESB)

http://en.wikipedia.org/wiki/Enterprise_application_integration

http://en.wikipedia.org/wiki/Enterprise_Integration_Patterns

http://www.eaipatterns.com/

http://www.eaipatterns.com/toc.html

http://www.kai-waehner.de/blog/2012/01/10/spoilt-for-choice-which-integration-framework-to-use-spring-integration-mule-esb-or-apache-camel/

Integrating Flex and Spring based JMS applications

http://java.dzone.com/print/12972

http://programmers.stackexchange.com/questions/92393/what-does-the-spring-framework-do-should-i-use-it-why-or-why-not

http://programmers.stackexchange.com/questions/157991/reasons-not-to-use-jsf

super() and this() in Constructor:

http://stackoverflow.com/questions/1168345/why-does-this-and-super-have-to-be-the-first-statement-in-a-constructor

Why Method Overloading is not possible by changing the return type of method?

http://stackoverflow.com/questions/442026/function-overloading-by-return-type

http://stackoverflow.com/questions/2744511/java-why-no-return-type-based-method-overloading

http://www.javatpoint.com/method-overloading-in-java

Covariant Return Types in Java 5

http://techgraffiti.blogspot.com/2009/09/covariant-return-types-in-java-5.html

Runtime Polymorphism (upcasting - parent object created through child):

http://www.javatpoint.com/runtime-polymorphism-in-java

http://stackoverflow.com/questions/6308178/what-is-the-main-difference-between-inheritance-and-polymorphism

abstract and final in a method - not possible

static and abstract keywords can not be used together.

Marker Interface: (interface with no member methods - ex: Serializable)

http://stackoverflow.com/questions/9858708/marker-interfaces-in-java

http://java.dzone.com/articles/marker-interfaces-java

http://stackoverflow.com/questions/1913098/what-is-the-difference-between-an-interface-and-abstract-class

Static Import in Java: (directly use static method without class qualifier)

http://stackoverflow.com/questions/420791/what-is-a-good-use-case-for-static-import-of-methods

http://stackoverflow.com/questions/14293712/what-are-checked-and-unchecked-exceptions

superclass method does not declare an exception

 (checked exception can not be handled in childclass).

String immutable:

http://www.javatpoint.com/immutable-string

Immutable Class:

http://www.javatpoint.com/how-to-create-immutable-class

Accessing final local variable in local inner class:

http://www.javatpoint.com/local-inner-class

Nested Interface:

http://www.javatpoint.com/nested-interface

Can a class have an interface?

Can an interface have a class?

http://stackoverflow.com/questions/1845731/inner-class-in-interface-vs-in-classhttp://docs.oracle.com/javase/tutorial/java/javaOO/nested.html

http://www.javatpoint.com/creating-thread

http://www.javatpoint.com/multitasking-in-multithreading

calling run() method instead of start() method - no seperate call stack

http://www.javatpoint.com/what-if-we-call-run()-method-directly

Daemon Thread - give service to other running threads - background

http://www.javatpoint.com/daemon-thread

static synchronization:

http://www.javatpoint.com/static-synchronization-example

http://www.javatpoint.com/synchronized-block-example

inter-thread-communication

http://www.javatpoint.com/inter-thread-communication-example

System.gc() - Daemon Thread - finalize keyword:

http://www.javatpoint.com/Garbage-Collection

Runtime class in Java:

http://stackoverflow.com/questions/506154/runtime-class-in-java

Runtime.getRuntime().exec("javac c:\java\abc.java -d c:\java\")

Runtime.getRuntime().exec("java c:\java\abc")

http://www.javaworld.com/jw-02-1999/jw-02-techniques.html?page=1

http://viralpatel.net/blogs/getting-jvm-heap-size-used-memory-total-memory-using-java-runtime/

http://viralpatel.net/blogs/jvm-java-increase-heap-size-setting-heap-size-jvm-heap/

http://viralpatel.net/blogs/java-resource-profile/

Java Decompiler:

http://viralpatel.net/blogs/decompile-class-file-java-decompiler-class-java-class/

Serialization:

http://www.javatpoint.com/serialization

http://www.javatpoint.com/reflection6

DeadLock:

Odd, Even number generator threads:

Threads communicating through Pipes (PipedReader, PipedWriter):

http://java-success.blogspot.com.au/2011/12/more-java-multi-threading-interview.html

queue is a First-In-First-Out (FIFO) - BlockingQueue:

http://java-success.blogspot.com.au/2012/04/multi-threading-with-blocking-queues.html

ThreadLocal - Thread-Safe:

thread-safe singleton:

http://java-success.blogspot.com.au/2012/03/java-multi-threading-interview.html

1. Use of synchronized block

2. eagar initialization vs lazy initialized when accessed

3. lazy initialization with static inner class

Thread Race Condition:

http://java-success.blogspot.com.au/2012/03/java-multi-threading-interview.html

RESTful Client - FireFox - Poster (a SoapUI like tool)

https://addons.mozilla.org/En-us/firefox/addon/poster/

AOP vs Dynamic Proxy:

java.lang.reflect.Proxy

java.lang.reflect.InvocationHandler

Thread Dumps:

http://howtodoinjava.com/2012/12/19/how-to-get-thread-dump-in-linux-using-jstack/

http://helpx.adobe.com/cq/kb/TakeThreadDump.html

JMeter - BadBoy (Browser Recorder):

http://java-success.blogspot.com.au/2011/10/jmeter-interview-questions-and-answers.html

http://java-success.blogspot.com.au/2011/10/selenium-web-driver-interview-questions.html

Simulate OutOfMemory: (use hashcode() or equals())

http://java-success.blogspot.com.au/2012/05/memory-leak-in-java.html

HTTP Session - forward, redirect and post-back:

Forward: browser not aware of it (no URL change) - No extra network trip

Redirect: browser reload to different URL (URL change occurs)

http://java-success.blogspot.com.au/2013/05/top-20-java-technical-interview.html

http://java-success.blogspot.com.au/2011/10/servlets-interview-questions-and.html

Client-pull or client-refresh (aka server polling):

You can use the tag for polling the server. This tag tells the client it must refresh the page after a number of seconds.

servlet clustering - memory replication of sessions

How do you send a file to a browser from your web application? I.e. how do you download a file from your web application?

response.setContentType(“application/x-download”);

response.setHeader(“Content-disposition”, “attachment;filename=” + fileName);