12 Java Interview Q & A for Fresher
1. What is Java and its basic characteristics?
Java is a high-level, object-oriented programming language that is platform-independent, meaning it can be executed on any operating system without any modification to the code. Java was developed by James Gosling at Sun Microsystems in the 1990s and is now owned by Oracle Corporation. Java's basic characteristics include being easy to learn, write, and maintain and having strong memory management and security features. Java is widely used for developing desktop applications, web applications, mobile applications, and games.
2. What is the distinction between a JDK, a JRE, and a JVM?
JDK (Java Development Kit) is a software development kit that includes the Java compiler, Java runtime environment (JRE), and other development tools.The setting in which Java applications are executed is known as the JRE (Java Runtime Environment). Java bytecode is executed by the JVM (Java Virtual Machine), a virtual machine. In other words, JDK is used to develop Java applications, JRE is used to run Java applications, and JVM is used to execute the compiled Java code.
3. What are the access modifiers in Java and their significance?
Java has four access modifiers: private, protected, public, and default (no modifier). Private variables and methods are only accessible within the same class. Protected variables and methods are accessible within the same class and its subclasses. You can access public variables and methods from anywhere. Default variables and methods are accessible within the same package. Access modifiers are used to control the visibility and accessibility of variables and methods in Java.
4. What are the difference b/w abstract classes and interfaces?
An abstract class is a class that cannot be instantiated, meaning it cannot be used to create objects. It is meant to be subclassed and provides a template for its subclasses to follow. An interface, on the other hand, is a contract that specifies a set of methods that a class must implement. Unlike abstract classes, interfaces cannot have method implementations. Although a class can extend one abstract class, it can implement numerous interfaces.
5. What are the different types of exceptions in Java?
Checked exceptions and unchecked exceptions are the two forms of exceptions in Java. Checked exceptions are exceptions that must be caught or declared by the calling method. IOException, SQLException, and ClassNotFoundException are examples of checked exceptions. Unchecked exceptions are exceptions that do not need to be caught or declared. Examples of unchecked exceptions include NullPointerException, ArrayIndexOutOfBoundsException, and ClassCastException.
6.What is the difference b/w checked and unchecked exceptions?
Checked exceptions are checked at compile-time and must be caught or declared, while unchecked exceptions are not checked at compile-time and do not need to be caught or declared.
7. What is the difference b/w an error and an exception?
An error is a severe problem that occurs at runtime and cannot be recovered from, while an exception is a less severe problem that can be recovered from. Errors are generally caused by the system or environment and are not recoverable by the program, while exceptions are caused by the program itself and can be handled by the program.
8. What is a thread in Java and how does it differ from a process?
A thread is a lightweight process that runs concurrently with other threads within the same process. A process is a separate instance of a program that runs independently and has its own memory space. Threads share the same memory space and resources as other threads within the same process, while processes have their own memory space and resources.
9. What are the different ways to create a thread in Java?
There are two ways to create a thread in Java: by extending the Thread class and by implementing the Runnable interface. Extending the Thread class involves overriding the run() method and calling the start() method to start the thread. Implementing the Runnable interface involves implementing the run() method and passing an instance
of the implementing class to a Thread object and calling the start() method to start the thread.
10. What is synchronization in Java and how is it achieved?
Synchronization is the process of ensuring that only one thread can access a shared resource at a time. The synchronized keyword in Java is used to achieve synchronization. By synchronizing a method or a block of code using the synchronized keyword, only one thread can execute that method or block of code at a time. This prevents multiple threads from accessing the shared resource simultaneously and causing race conditions.
11. What are the different types of locks available in Java?
Java provides two types of locks: intrinsic locks and explicit locks. Intrinsic locks are also known as monitor locks and are acquired by using the synchronized keyword. Explicit locks are acquired and released manually using the Lock interface and its associated classes.
12. What is a Java bean and how is it different from a regular Java class?
A Java bean is a special type of Java class that conforms to a set of conventions. Java beans are used to encapsulate data and provide getter and setter methods to access and modify the data. Java beans also provide a default constructor and implement the Serializable interface, which allows the object to be serialized and deserialized.
In terms of Java training and education, it is important to have a solid understanding of these fundamental concepts in order to be successful in an interview and in a career in Java development. For those looking to learn Java, chennai software training institute can be a great way to gain a comprehensive understanding of the language and its concepts.
Java training institutes offer courses that cover a wide range of Java topics, including the ones mentioned above. These courses are typically taught by experienced Java developers who can provide valuable insights and real-world examples. In addition, Java training institutes often provide hands-on experience through projects and assignments, which can help students gain practical experience with the language.
For those who prefer a more flexible and self-paced approach, an online Java course may be a better option. Online courses typically offer video lectures, interactive exercises, and quizzes to help students learn the material at their own pace. Many online courses also offer support through forums or chat rooms where students can ask questions and receive feedback from instructors and peers.
Overall, whether you choose to attend a Java training institute or take a java online course, it is important to have a solid understanding of the fundamental concepts of Java. This will not only help you in an interview but also in your career as a Java developer.
No comments yet