93 Java interview questions you should be asking

Method overloading with type promotion in Java is the process of defining multiple methods in the same class with the same name but different parameter types. It is because the super() is used to call the parent class constructor. But there is the condition that super() must be the first statement in the block. Now in this case, if we replace this() with super() then also it will throw the compilation error. Because this() also has to be the first statement in the block. So in conclusion, we can say that we cannot use this() and super() keywords in the same block.

Until the thread inside the synchronized block exits the block, all other threads trying to enter the block are blocked. Primitive data types like int, float, and others are typically present in an array. In such circumstances, the array immediately saves these elements at contiguous memory regions. Instead of the actual object, an ArrayList includes the references to the objects’ many locations in memory. The objects are not kept in consecutive memory regions because of this.

DoOn callbacks in Project Reactor are a set of operators that allow developers to perform side-effects at various points in a reactive stream. These side-effects can include logging, error handling, or updating external state. DoOn callbacks are non-blocking and do not affect the flow of the reactive stream. Reactive Streams are a specification for asynchronous stream processing with non-blocking backpressure in Java. You should use parallel streams in Java when you have a large dataset that can be easily partitioned and processed independently. Parallel streams can help improve the performance of your application by utilizing multiple cores and processors.

Interview Questions List

Java EE, by comparison, is a platform built on top of Java SE. It provides an API and runtime environment that can be utilized for running large-scale, multi-tiered, and secure network applications. Java EE includes many components of the Java Standard Edition (Java SE). Sleep() is a method that’s used to pause a process for a few seconds or a specified period of milliseconds.

In the last five years, the default database for small-scale projects and startups has been a NoSQL solution like MongoDB or Couchbase. After a few years of use, the industry is considerably more aware of the benefits and drawbacks of NoSQL solutions. To observe the candidate code a solution to the issue statement during the pre-screen, you can utilize a web code editor such as Etherpad or Google Docs.

Q7. What are the differences between ServletContext vs ServletConfig?

This can be useful when there are certain fields in an object that should not be exposed to the client or stored in the database. You can modify a JsonNode in Java by using the set() method to set a new value for a specific field or by using the with() method to create a new JsonNode with a modified value. You can configure Jackson to ignore unknown fields by setting the mapper feature “FAIL_ON_UNKNOWN_PROPERTIES” to false.

The volatile keyword basically says to the JVM “Warning, this variable may be modified in another Thread”. The goal of this interview question is to check the previous experience of senior Java developer candidates, with a focus on how they propose new solutions instead https://trading-market.org/ of sticking to the plan. Typically, performance issues are reported by testers or users sometime after a feature has been shipped to production. Identifying the root cause of the issue can be difficult, so this is a good interview question for experienced candidates.

• Especially useful to keep in mind that the spring framework’s central features are essentially conducive to any Java application.
• Once it’s been set, it can’t change its value anymore, for instance in the functions.
• Parallel streams can potentially provide faster performance than regular streams when processing large datasets or performing computationally intensive tasks.
• It enhances security, caching, synchronization, and performance of the application.
• Apart from these direct Java tech and awareness questions, there is a possibility to check your Java debugging and application server-related experiences.

I’ll uncover one of my favorite questions to ask during interviews, especially with experienced candidates who’ve probably used SOAP in legacy projects. Java is also similar to C and C++ but is simpler and enforces an object-oriented programming model. People use Java for applications that can run on a single computer or can be spread amongst servers. Java is known to be the write once, run anywhere coding language. Or are you looking to hire a Java developer for your team or a client? There are plenty of Java developers out there waiting to grab their next best job opportunity so perhaps it’s time to boost your recruitment results too.

Could you please describe what the software development life cycle is and why it is important?

The primitive and object and classes of Java, on the other hand, are not consistent. C++ is a programming language that is based on the C programming language. Enums are essentially final classes with a fixed number of instances. They can implement interfaces but cannot extend another class.

Dynamically expanding array lists make it possible to add new elements at any time. The underlying data structure of the ArrayList is an array of the Object class. There are available readObject and writeObject methods specific to it.

An infinite loop will terminate automatically once the application exits. In Java, a local variable is typically used inside a method, constructor, or a block and has only local scope. Thus, this variable can be used only within the scope of a block. The best benefit of having a local variable is that other methods in the class won’t be even aware of that variable. How is the creation of a String using new() different from that of a literal? Whereas, if we create a string using the string literal syntax, it may return an already existing object with the same name.

What are the differences between Views and Tables?

Let us now move on to the crucial senior software engineer interview questions. This article will provide a list of crucial senior engineer interview questions to ask potential engineering and dev team leads. We’ll also discuss why you should ask these questions and how you can build on them to discover the perfect senior software engineer for your role. Object cloning in Java is the process of creating an exact copy of an object. It basically means the ability to create an object with a similar state as the original object. To achieve this, Java provides a method clone() to make use of this functionality.

Java Reflection allows you to analyze classes, interfaces, fields, and methods during runtime without knowing what they are called at compile time. Reflection can also be used to create new objects, call methods, and get/set field values. External, user-defined classes can be used by creating instances of extensibility objects with their fully-qualified names. Debuggers can also use reflection to examine private members of classes. As you can see, interview questions can reveal a lot about an applicant’s experiences, education, and skills.

In short, how strong is their intellectual interest in their chosen field? Committed, inquisitive candidates will stand out when asking technical interview questions. Ultimately, senior Java developer interview questions will seek to evaluate a candidate’s depth and breadth of knowledge. Prepare by studying recent trends and Java updates, understanding the business’ unique needs, and brushing up on skills that you’re already familiar with so you can guide others. For generic exceptions, most of the times we serve static pages. Spring Framework provides HandlerExceptionResolver interface that we can implement to create global exception handler.

Learn Java and Programming through articles, code examples, and tutorials for developers of all levels. The volatile keyword tells the JVM when a variable may be modified in another threat. The volatile keyword guarantees global ordering on reads and writes to a variable. It ensures that every thread accessing a volatile field will read the variable’s  current value, instead of a cached value.

This was leading to OutOfMemoryError in java to reduce that Oracle removed permgen and added MetaSpace which grows automatically and reduces generating the famous OutOfMemoryError. It means we’ll create only one instance of that static member that is shared across all instances of the class. 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. I still remember the early years of programming as a nightmare, when we used SVN in a team of 10 people. Using Git improved the game, but we all needed some experience with it. You can be sure that JDK has the best implementation for the Java language.

Similarly, you cannot override a private method in subclass because it’s not accessible there. What you can do is create another private method with the same name in the child class. Let’s take a look at the example below to understand it better. This 120+ core java interview question and answer will help freshers and experience to crack the interview in 1st attempt. Java String pool refers to a collection of Strings which are stored in heap memory.

By default, the JIT compiler is enabled in Java and is activated whenever a Java method is invoked. The JIT compiler then compiles the bytecode of the invoked method into native machine code, compiling it “just in time” to execute. Once the method has been compiled, the JVM summons the compiled code of that method directly rather than interpreting it. This is why it is often responsible for the performance optimization of Java applications at the run time. Wrapper classes convert the Java primitives into the reference types (objects).

String objects are cached in the String pool, making them immutable. In Java, one can apply the final keyword to a variable, methods, and class. java interview questions for senior developer 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.

On Heap memory, garbage collection is employed to release the memory used by objects with no references. Every object created in the Heap space has access to the entire application and may be referred to from anywhere. A collection of strings in Java’s Heap memory is referred to as Java String Pool. In case you try to create a new string object, JVM first checks for the presence of the object in the pool.

• The main () function is where the compiler begins programme execution in every Java programme.
• If your team has a certain development approach, it is critical that the applicant knows it and has prior experience with it.
• DoOn callbacks in Project Reactor are a set of operators that allow developers to perform side-effects at various points in a reactive stream.
• This method enhances the code readability and gets direct access to the static members.

Data encapsulation is one of the properties of OOPS concepts, where all the data such as variables and methods are enclosed together as a single unit. Implementing a thread using the method of Runnable interface is more preferred and advantageous as Java does not have support for multiple inheritances of classes. 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. Java programs include a large amount of runtime information that is used to resolve access to objects in real-time. Binding is a process of unifying the method call with the method’s code segment.

Both methods serve as a hint to the JVM to start a garbage collection. However, it’s up to the JVM to start the collection right away or later. The Spring beans are the objects that form the keystone of your application and are controlled by the Spring IoC container.

Within the same class, you can repeat this pattern of declaring a static field and immediately initializing it, since multiple static initializers are allowed. List and explain the purpose of the three types of class loaders. Once we hit the base case, the work is done – below is that same function, “unrolled”. Any interface which is having single abstract can be called a Functional Interface. 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 the event that an exception is not caught, it is initially thrown from the top of the stack and then moves down the call stack to the preceding method. The runtime system looks for a way to handle an exception that a method throws. The ordered list of methods that were called to get to the method where the error occurred is the collection of potential “somethings” that can be used to manage the exception. The call stack is the list of methods, and exception propagation is the search technique. Next, it’s best to test the waters and ask the basics of Java development.

Yes, even with a garbage collector in place, the programme could still run out of memory. Garbage collection aids in identifying and removing programme objects that are no longer needed in order to release the resources they use. When an object in a programme cannot be reached, trash collection is executed with respect to that object. If there is not enough memory available to create new objects, a garbage collector is used to free up memory for things that have been removed from the scope. When the amount of memory released is insufficient for the creation of new objects, the program’s memory limit is exceeded.