In java 8, Permgen is replaced by Metaspace, we should be able to answer what advantage it offers. Generally speaking, Redis was not built to achieve this. Retrieving vast chunks of data has been indicated as one of the worst practices. A way better solution could be to store the data object in a standard NoSQL database.

Java Champion James Ward on the State of Java and JVM Languages –

Java Champion James Ward on the State of Java and JVM Languages.

Posted: Mon, 29 Aug 2022 07:00:00 GMT [source]

In the case of a shallow copy, primitive data types are copied, whereas in the case of a deep copy along with primitive data types the object references are also copied. Final is used to restrict classes, variables, or methods, the final keyword. Generally, instance variables are declared in a class but outside methods whereas a local variable is declared within the blocks of code. The term “this” is a particular keyword designated as a reference keyword. The “this” keyword is used to refer to the current class properties like method, instance, variable, and constructors.

You need to implement the Iterable interface if you want to loop over advanced for loop in Java, though. If you implement Collection then you by default get that property. It’s a doubly linked list, you can check the code in JDK. In Eclipse, you can use the shortcut, Ctrl + T to directly open this class in Editor.

ClassLoader is the “deepest” mechanism in Java, which allows you to intervene practically into the core of the Java Virtual Machine while remaining within the framework of Java programming. ClassLoader provides loading the classes from the local file system, remote file system, or web. Core Java is a general term used by Sun Microsystems to define a basic edition of Java , used for the other editions created. Core Java is mainly used for building desktop and server-based apps, mostly because of its benefits as the fast and a highly-secure scripting language. I hope you are getting good insights from the actual interview questions. Apart from these direct Java tech and awareness questions, there is a possibility to check your Java debugging and application server-related experiences.

Batch processing helps you to group related SQL statements into a batch and execute them instead of executing a single query. By using batch processing technique in JDBC, you can execute multiple queries which makes the performance faster. The ResultSetMetaData interface returns the information of table such as total number of columns, column name, column type etc. It can be used to change the cursor pointer and get the information from the database. To get the MIME type of a file or application session related information is stored using servlet context object.

GraphQL is an API design architecture, but with a different approach that is much flexible.

Hiring managers need to prepare advanced Java interview questions in order to fully evaluate the technical knowledge of a candidate. On the other hand, candidates need to also repeat the basic information prior to the interview in order to fully showcase their potential. Static methods cannot be overriddenbecause they are not dispatched on the object instance at runtime.

  • Behavioral – These are about identifying common communication patterns between objects.
  • Late binding happens when the method’s code segment is unknown until it is called during the runtime.
  • Similar to the previous question, the difference between Adapter and Proxy patterns is in their intent.
  • System.out is used to display normal messages and results.
  • Another great question to check the all round knowledge of Java developers.
  • Dependency injection frameworks lean heavily on reflection.

Wait() is generally used in multithreaded applications, in conjunction with notify() / notifyAll(), to achieve synchronization and avoid race conditions. However, it is worth noting that if performance is that critical, it’s better to just use an array and manage it yourself, or use one of the high performance 3rd party packages such as Trove or HPPC. LinkedList, on the other hand, is implemented using a doubly linked list. As a result, an inserting or removing an element only requires updating the links that immediately precede and follow the element being inserted or removed. Fail-safe iterates operate on a cloned copy of the collection and therefore do not throw an exception if the collection is modified during iteration. Examples would include iterators returned by ConcurrentHashMap or CopyOnWriteArrayList.

Spring Interview Prep List

A session is essentially defined as the random conversation’s dynamic state between the client and the server. The virtual communication channel includes a string of responses and requests from both sides. The popular way of implementing session management is establishing a session ID in the client’s communicative discourse and the server. The setDaemon() method creates a Daemon thread in Java. It is the simplest way of executing the computer code that takes in compilation during the execution of a program rather than before performance. JRE has class libraries and other JVM supporting files.

If a variable for an object is removed from the programme while it is running, the object may be trash collected. They are also referred to as inaccessible objects occasionally. The new operator returns a reference to an object after dynamically allocating memory for it. Yes, even with a garbage collector in place, the programme could still run out of memory.

What do you mean by promise, also explain its states?

java interview questions for senior developer makes use of the database and configuration data to provide persistence services to the application. It includes many objects such as persistent object, session factory, transaction factory, connection factory, session, transaction etc. Copy constructor is a member function that is used to initialize an object using another object of the same class. Though there is no need for copy constructor in Java since all objects are passed by reference.

structures and algorithms

List and explain the purpose of the three types of class loaders. Interfaces have been able to provide code via default methods for years . Synchronized Throwable getCause() – This method returns the cause of the exception or null id as represented by a Throwable object.

A synchronized block of code can be executed by only one thread at a time. As Java supports execution of multiple threads, two or more threads may access the same fields or objects. Synchronization is a process which keeps all concurrent threads in execution to be in sync. Synchronization avoids memory consistency errors caused due to inconsistent view of shared memory. When a method is declared as synchronized the thread holds the monitor for that method’s object.

public static void main(String args )

Spring manages and contains the configuration of application objects, as well as their life cycles. In the example below, continent class is sub-class of world class and it’s super class of country class. Do While Loop is same as While loop with only difference that condition is checked after execution of block of statements.

It separates the business-specific logic from the presentation layer from each other. Behavioral – These are about identifying common communication patterns between objects. Creational – These are about object creation or class instantiation. Further, these patterns are categorized into object-creational patterns and class-creational patterns. Throttling will prevent a specific device from making a defined number of requests within a defined time. Upon exceeding the specified number of requests, 429 Too Many Attempts HTTP error should be thrown.

catch block

Optimize your software development capabilities by adding top talents from one of the leading outsourcing companies in the world; let our experience work for you. The GET method in HTTP should be used only to retrieve resources from a web server, without altering the state of the application in any way. In this case, a slight modification to the state of the application might be tolerable. The most common pitfall that the candidate should be aware of is the probable performance drop when using AOP, as it uses reflection under the hood, and Java reflection isn’t free .

The string class is immutable but the other two are mutable in nature. StringBuffer is synchronous whereas the StringBuilder is asynchronous. String uses string pool as memory storage whereas the other two use heap memory for storage purposes. In Java, one can apply the final keyword to a variable, methods, and class. With the help of the final keyword, the variable turns out to be a constant, the method cannot be inherited and the class cannot be overridden. It is because the super() is used to call the parent class constructor.

This question tests the candidate’s understanding of Kotlin. They should provide an example of features they like in this programming language. A static method is a method that belongs to a class, rather than an instance of a class. This means that you can call it without creating an instance of the class first. A non-static method is a method that belongs to an instance of a class. In other words, this means that you can only call it if you have an instance of the class.


Debuggers can also use reflection to examine private members of classes. The best way to prepare for this question is to decompile the JDK code and see what’s inside with your own eyes. Memory for all class instances and arrays is allocated to this heap, which is created at the JVM start-up.

Synchronization helps to execute threads one after another. The constructor chaining follows the process of inheritance. The constructor of the sub class first calls the constructor of the super class.