Top 50 Java Programming Interview Questions

A daemon thread in Java is a low-priority thread that is used to perform background operations or tasks which are used to perform continuously. Such as Garbage collection, Signal dispatches, Action listeners, etc. Daemon threads in Java have lower priority than user threads, which means they can only execute when no user threads are running. Daemon threads in Java are useful features that are required for background tasks that do not require explicit shutdown or finalization. It allows more efficient use of system resource and are used to simplify resources and can simplify long-running tasks.

Show examples of overloading and overriding in Java.

In Java, it essentially means the ability to create an object with a similar state as the original object. What if we add another value object with the same key as entered before? Well, after determining the index position of Entry object, while iterating over LinkedList on calculated index, HashMap calls equals() method on key object for each Entry object. All these Entry objects in LinkedList will have a similar hash code but equals() will test for true equality.

Which method should developers use to complete dependency injection?

Java Abstraction is the term in Java, which means encapsulating only the function ability and behavior of methods while not exposing their implementation details to the user. The object design used here focuses on what an object does rather than on how it performs that function. The compiler checks checked exceptions at compile time, meaning that programmers have to handle such exceptions with try-catch blocks or declare them using the method signature. Unlike checked exceptions, unchecked exceptions are not checked at compile-time, hence they do not require explicit handling by a programmer.

What is the static method?

This integer is used for determining the bucket location when this object needs to be stored in some HashTable like data structure. By default, the Object’s hashCode() method returns an integer representation of the memory address where the object is stored. If the JVM exits while the try or catch code is being executed, then the finally block may not execute.

Can developers import the same package two times in Java?

A thread has its own program counter, execution stack, and local variables, but it shares the same memory space with other threads in the same process. Java provides built-in support for multithreading through the Runnable interface and the Thread class. The HashSet class implements the Set interface in the Java Collections Framework and is a member of the HashSet class. Unlike duplicate values, it stores a collection of distinct elements. In this implementation, each element is mapped to an index in an array using a hash function, and the index is used to quickly access the element.

Buffering allows programs to write a big amount of data instead of writing it in small chunks. This also reduces the overhead of accessing java interview questions for senior developer the network or the disk. The key difference between them is that byte stream data is read and written by input/output stream classes.

Main-Class is the entry point of the jar and used by java command to execute the class. Yes, we can have try-finally statement and hence avoiding catch block. A local inner class without a name is known as an anonymous inner class. An anonymous class is defined and instantiated in a single statement. Anonymous inner class always extend a class or implement an interface.

  1. In this blog post, we will discuss the top Java interview questions that you are likely to face.
  2. There is no limit to the number of major approaches you can use.
  3. Stack memory in data structures is the amount of memory allocated to each individual programme.

Therefore, it can be useful where there are many additions or removals. Yes, a Java interface can have static methods, but we cannot override them as they’re static. So, we have to define the static methods in the interface and only perform the calling party in the class. If an object contains another object and the contained can’t exist without the existence of that particular object, then it’s known as the composition. In simple words, the composition is a kind of aggregation used to describe the reference between two classes using the reference variable.

With regard to invocation, the reference type will decide the version of overloaded method that is used. 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.

The term “enum” is commonly used to refer to an enumeration. An enumeration represents an interface that encompasses methods facilitating access to the underlying data structure from which the enumeration is derived. It enables a systematic, sequential retrieval of all the elements stored within the collection.

A stack is based on the principle of Last In, First Out (LIFO). A queue is different in that it’s based on the First In, First Out (FIFO) principle. The pressure to perform well in an interview can feel overwhelming. Despite your knowledge and experience, nervousness could get in the way of putting your best foot forward.

When a Java program contains more than one method with the same name but with different properties, then it is called method overloading. For that matter in any class, changes can happen in data in runtime and changes in implementation can happen in future releases. So, encapsulation applies to both i.e. data as well as implementation. The native keyword is applied to a method to indicate that the method is implemented in native code using JNI. It marks a method, that it will be implemented in other languages, not in Java.

The task of java compiler is to convert java program into bytecode, we have javac executable for that. So it must be stored in JDK, we don’t need it in JRE and JVM is just the specs. The process of converting stream data created through serialization to Object is called deserialization. We can run the garbage collector with code Runtime.getRuntime().gc() or use utility method System.gc().

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