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Hibernate Questions on Important Differences for Self Assessment

These are some of the commonly asked questions to check if you know the differences between important concepts or APIs in Hibernate. This may contain beginner to advanced level questions.

 

  1. Differentiate between entities and value types in Hibernate.

  2. What is the difference between save() and persist() methods in Hibernate?

  3. What is the difference between get and load methods in hibernate?

Different Ways to Configure in Hibernate 4.3

Before working with hibernate in your code, you will need to configure Hibernate with information regarding your database such as host, port, credentials etc. You also need to create mappings that tell hibernate how to map the state of a Java entity to the columns of its corresponding table.

We can configure various hibernate features either through annotations or through xml files (hbm files). Preferred approach currently is annotations.

 

You can configure Hibernate mainly in three ways:

Hibernate Essentials Questions for Self Assessment

This is a list of basic questions from Hibernate which you can use to check your understanding or even prepare for interviews. You may use the parent chapter, other chapters or hibernate or the forum to discuss more on these questions.

 

  1. What is a framework?

  2. What do you mean by CRUD?

  3. What is Hibernate? What are the advantages of using Hibernate?

  4. What is Java Persistence API (JPA)?

LinkedHashMap Class

LinkedHashMap extends HashMap and has a predictable iteration order.

 

Properties of LinkedHashMap

  1. LinkedHashMap implementation maintains a doubly-linked list running through all of its entries.

  2. The doubly linked list maintained by the LinkedHashMap implementation defines the iteration ordering.

  3. By default, the order is the order in which keys were inserted into the map.

[Assignment Problem] Multi-threaded Series Printer

Problem

Write a multi-threaded program to print data from four series of data in alternating order.

There are four series of data are as below:

Series 1:              0,            4,            8,            12,          …

Series2:               1,            5,            9,            13,          …

Series3:               2,            6,            10,          14,          …

[Lab-Analysis] Setting Up For Rest Web Services Development Using Maven Jersey Archetype

In the lab @ http://javajee.com/setting-up-the-environment-for-developing-rest-web-services-with-jersey-using-maven, you setup the environment and executed a REST service.

Below are the important files generated, as you can see from the eclipse Project Explorer:

[Lab] Setting Up For Rest Web Services Development Using Maven Jersey Archetype

Jersey is a popular JAX-RS implementation.

Jersey is the open source, production quality, JAX-RS (JSR 311) Reference Implementation for building RESTful Web services.

In addition to being the Reference Implementation, Jersey also provides an API so that developers may extend Jersey to suit their needs.

You can download JAX-RS from Jersy Homepage at jersey.java.net. You can also set it up using a build tool such a maven.

 

REST Based Web Services Development with JAX-RS

Java API for XML – Restful web services (JAX–RS) is the standard specification for developing REST web services.

JAX-RS uses annotations to simplify the development and deployment of web service clients and endpoints. Important JAX-RS annotations can be used @ http://javajee.com/important-jax-rs-annotations.

 

Getting Familiar with the BlockingQueue Interface

A Queue is a first in first out (FIFO) data structure, as we have already seen.

BlockingQueue is a queue that additionally supports operations that wait for the queue to become non-empty when retrieving an element, and wait for space to become available in the queue when storing an element.

BlockingQueue methods come in four forms:

  1. those that throws an exception,

[Problem] Three Thread Synchronization Using State Pattern

Problem

Create three threads

  • one that print '1' for 5 times.

  • one that print '2' for 5 times.

  • one that print '3' for 5 times.

Need to implement coordination between them so that  1, 2 and 3 should be printed in order from the three threads:

1

2

3

1

2

3

...

Hint: The order should be same theoretically and practically. Putting a sleep while printing might work in some cases, but it cannot be guaranteed always.

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