Enterprise Java – Interview questions & answers . The reason I chose “Java /J2EE Job Interview Companion” is because . How many years of experience. These interview questions and answers on Advanced Java will help you strengthen your technical skills Interview preparation PDF was generated at Monday 12th January, J2EE will be more friendly and efficiency in the code. If you're looking for J2EE Interview Questions for Experienced or Freshers, you are at right place. There are lot of opportunities from many reputed companies in .
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Top 50 J2EE interview questions & Answers. 1) What is J2EE? J2EE means Java 2 Enterprise Edition. The functionality of J2EE is developing multitier web-. The J2EE platform is consists of a set of services, application programming Top 50 J2EE interview questions & Answers .. Download PDF. Advanced J2EE Interview Questions and Answers for Freshers or Experienced Pdf. This interview section questions contains a brief introduction to the Java.
The functionality of J2EE is developing multitier web-based applications. Application clients components. Servlet and JSP technology are web components. Business components JavaBeans. Wireless clients, based on MIDP technology. Servlets are Java programming language that dynamically receives requests and makes responses. JSP pages execute as servlets but allow a more natural approach to creating static content.
In this post, you will find questions which are asked to check whether a candidate has required skills to support Java application or not. If you are working in production services or supporting Java application, these interview question will help you to do well on your interview.
If you moving from development to support role then also these questions will give you a good idea about what is expected from a Java JEE support engineers.
The keyword which you use with grep for search can be anything unique to your process, something which appears in its command line e. You can also do "ps -ef grep java" to list all Java process. First, you need to find the PID of your process, which you can find by using the "ps" command as shown in the previous question. Alternatively, you can also use the prstat command as shown here. These are parameters to specify heap size in Java.
The -Xms defines the size of the heap when JVM starts up and -Xmx is used to specify the maximum heap size for Java application i. You install JRE to run Java application e. Applet or Core Java application or Web server like Tomcat.
There is some threshold set if a code runs more than the threshold it becomes the candidate of just in time compilation by JIT. These are parameters to specify heap size in Java.
The -Xms defines the size of the heap when JVM starts up and -Xmx is used to specify the maximum heap size for Java application i. You install JRE to run Java application e.
Applet or Core Java application or Web server like Tomcat.
There is some threshold set if a code runs more than the threshold it becomes the candidate of just in time compilation by JIT.
There are many ways to take the heap dump of a Java process e. Tomcat, but most common is by using tools available in JDK e. Remember, you also need PID of Java process which you can find by using "ps" and "grep" command as discussed in the first question. You can see Java Performance Companion by Charlie Hunt to learn more about taking and analyzing heap dump in Java to find memory leak and other memory related errors.
Taking thread dump is easier than taking heap dump because you don't need to remember tool. In Linux, you can just use the kill command to take the thread dump e. How do you deal with that? The Java virtual machine throws java. OutOfMemoryError when there is not enough memory to run the application e. The most common OutOfMemoryError is the java. OutOfMemoryError: java heap space , which comes when there is no more memory left to create a new object.
Windows 8 or later versions of Linux. From Java developer's perspective, the main difference between them comes from heap size.
If your program needs more memory, better run it on bit JVM with large heap space. See here to learn more about bit and bit JVM. It's one of the key components and allows an application developer to focus on application development rather than doing memory management.
Some of the popular garbage collectors are a Concurrent Mark-Sweep garbage collector and G1 garbage collector in recent times.
There are many tools to analyze heap dump in Java e. Though both httpd and Tomcat are products of Apache software foundation, the httpd is more popular and used across the web and not just in Java world. You can also use both Apache httpd and Tomcat together in Java world.
Yes, you can use Apache and Tomcat together. There are many Java web application which is fronted by Apache web server to deliver static resources e.
HTML files, images, configuration files etc.
You can then configure Apache to forward the request to Tomcat. When you install Tomcat in Linux by unzipping the downloaded package, you can see that there is a startup.
These scripts are used to start and stop Tomcat in Linux. These scripts internally call Catalina. Different Java vendors e. Since almost every enterprise application has a database, JDBC is very important for any real world projects.
Since creating a new database connection in real-time is an expensive process and can potentially slow down the response time, many application maintains a pool of active database connection. When a request comes in they retrieve a connection from the pool, get the data from the database and then return the connection back to pool so that it can be reused.
This way, response time is improved in most of the Java web application. See here to setup a database connection pool in Tomcat using Spring framework. Suddenly your database goes down?