Top 25+ Java Developer Interview Questions

Java is known for its object-oriented programming structure. Real-world items or subjects turn into code as objects, and these objects communicate with other objects. Then, these objects interact to create a well-rounded application.

Each attempt block does not necessarily have to be followed by a catch block. Either a catch block or a final block ought to come after it. Additionally, any exceptions that are expected to be thrown should be mentioned in the method’s throws clause. The package is a collective bundle of classes and interfaces and the necessary libraries and JAR files. Primitive and object types in C++ have the same kind of semantics.

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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.

java developer interview questions

Finalize is used to call the function of the implementation of cleaning the garbage collection of an object. It is the simplest way of executing the computer code that takes in compilation during the execution of a program rather than before performance. Now, let’s have a look at some of the most asked Java technical interview questions for intermediate experienced professionals. I don’t know about the program, but generally, three objects are eligible for garbage collection.

What is Java platform independence?

It can be used to change the cursor pointer and get the information from the database. An aggregation is a specialized form of Association where all object has their own lifecycle but there is ownership and child object can not belong to another parent object. A single teacher can not belong to multiple departments, but if we delete the department teacher object will not destroy. In Java, super() and this(), both are special keywords that are used to call the constructor. When a class is declared as final in Java, it can’t be extended by any subclass class but it can extend other class. As we have synchronized this function, this thread can only use the object after the previous thread has used it.

  • An error is an irrecoverable condition occurring at runtime.
  • Statement execute(String query) is used to execute any SQL query and it returns TRUE if the result is an ResultSet such as running Select queries.
  • You cannot override a private or static method in Java.
  • Classloader is a subsystem of JVM which is used to load class files.
  • Because there must be only 1 main method in the java program as the execution starts from the main method.
  • No, we cannot change the scope of the overridden method in the subclass.
  • This driver is used to send JDBC calls to the network protocol which is understood by the database server.

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. A Copy Constructor in Java is a constructor that initializes an object through another object of the same class. The term aggregation refers to the relationship between two classes best described as a “whole/part” and “has-a” relationship. This kind is the most specialized version of an association relationship.

Q8. How to handle exceptions in Spring MVC Framework?

Conversely, when a String formation takes place with the help of a new() operator, interning does not take place. The object gets created in the heap memory even if the same content object is present. Singleton classes are those classes, whose objects are created only once. And with only that object the class members can be accessed. Both class methods have the name walk and the same parameters, distance, and time.

They are not used in Java because they are unsafe(unsecured) and complex to understand. There are the following differences between the Java platform and other platforms. In the above code, for any number n, we find all the 2 pairs of numbers that are added together resulting in n.

Core Java – OOPs Concepts: Method Overriding Interview Questions

In other words, code points outside of the BMP (Basic Multilingual Plane), that is, code points having a value of U+10000 or above, will be ignored. Classpath is very specific to Java and used for locating class files by java executables. It can be a directory, ZIP files JAR files, etc. when we provide classpath location while running java application. With this fierce competition going around, organizations are quite determined in what they are looking for in a professional for Java developer post. Professionals with knowledge, skills, expertise, and Java certification who can efficiently design, code, develop, and deploy different kinds of applications are highly sought.

Using Java profiling you can monitor different JVM parameters, including object creation, thread execution, method execution, and yes, garbage collection. A memory leak is bad because it blocks memory resources and degrades system performance over time. Other than technical knowledge, it is also important to assess the candidate’s commitment. That is why you need to add this to your Java developer interview questions list. Ask them what drives them to work and choose to be a Java developer. The only way to access an object in the heap is through a pointer, while you don’t need a pointer to access an object on the stack.

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