Executing numerous things at once is known as multitasking. Errors are mostly caused by the environment in which the program is running. A FailFast iterator is an iterator that throws a ConcurrentModificationException if it detects that the underlying collection has been modified while the iterator is being used. This is the default behavior of iterators in the Java Collections Framework. Implemented frequently in the API by Calendar, Wrapper classes, Date, and String.

We will be using a static block of code when creating the objects at the class’s load time. Any statements within this static block of code will get executed at once while loading the class, even before creating objects in the main method. Multiple threads trying to access the same resources in a multi-threaded software may frequently result in unexpected and incorrect outcomes. Therefore, it must be ensured through some form of synchronization that only one thread can access the resource at any given time. Java offers a method for setting up threads and synchronizing their operations with the aid of synchronized blocks.

Give some features of the Interface.

Here, you’ll find all our resources for Java interview prep in one place, from courses and tutorials to walkthroughs on real-world interview problems. Before you start preparing for interviews, make sure you’re well-versed on the fundamentals of Java programming. java 7 certifications Check out our learning path tailored for Java for programmers . Functional interfaces are interfaces that have a single abstract method. Functional interfaces are implemented with Lambda expressions. The Lambda expression contains the body of the abstract method.

The String pool may return an existing object if we build an object using the String literal syntax, such as “Baeldung,” on the other hand. The first add() method accepts a single argument of type E, the element to be added to the list. A Paradigm that is based on the concepts of “Objects.” It contains data and code.

How do you handle security in Java applications, especially in web-based systems?

ODBC drivers must be installed to connect with the database. If we change any method to a final method, we can’t override it. As displayed in the above diagram, the byte can be promoted to short, int, long, float or double. The short datatype can be promoted to int, long, float or double.

  • The local variables are not initialized to any default value, neither primitives nor object references.
  • Java uses a technique called time-sharing, commonly referred to as time-slicing, to implement multi-threading on computers with a single CPU.
  • Here in Java, the wrapper class is an object class that encapsulates the primitive data types.
  • If you don’t deal with an exception once it occurs, the programme will end abruptly and the code after the line where the exception occurred won’t run.
  • Try these 10 Java code challenges for beginners and put your Java knowledge to use.

Iterator helps in iterating over a collection of elements sequentially. A thread is a single sequence of instructions within a process. Exceptions are responsible for abruptly terminating the running of the program while executing and the code written after the exception occurs is not executed. Error is an illegal operation performed by the user which causes abnormality in the program. Exceptions are the unexpected events or conditions that comes while running the program, exception disrupts the normal flow of the program’s instructions. It is performed in two classes with an inheritance relationship.

What is the difference between Checked Exception and Unchecked Exception?

The ServletContext object is shared by all the servlets in a web application. The main difference between the two methods is that forward() occurs entirely on the server side, while sendRedirect() involves a new request from the client. The doGet() method is used to handle HTTP GET requests, while the doPost() method is used to handle HTTP POST requests. The main difference between the two methods is that the GET request parameters are passed in the URL, while the POST request parameters are passed in the request body. If the applicant is more enthusiastic, they may explain how the application may be improved. Candidates who fail to name one may not have dealt with failure.

It can be used to change the cursor pointer and get the information from the database. – Supporting integration with external libraries or frameworks that recognize and operate on marker interfaces. When a class is declared as final in Java, it can’t be extended by any subclass class but it can extend other class. When a method is declared final then it can’t be overridden by the inheriting class.