Java Technical Interview Questions

Java

• What is the JVM?
• Define code compilation?
• What is a constuctor?
• What is the naming convention of variables in java?
• What is an annotation and give an example.
• What is the difference betwee '==' and equals() when comparing Strings?
• What are the 8 primitive types in Java?
• What is the difference between primitives and wrapper classes and when can we use each?
• Define Encapsulation and outline its benefits.
• What is the naming convention for JUnit test methods?
• When we compile our code, where do the compiled .class files live?
• Why is Behavior-Driven Development beneficial?
• What is the difference between an Array and an ArrayList? When do you use one over the other?
• What is a stacktrace? What does it do for us?
• Why is it best practice to declare attributes of a custom class private?
• When would we use char? What is its corresponding wrapper class?
• Do objects get passed by reference or value in Java? Elaborate on that.
• Explain the four OOP principles.
• What is the difference between Abstract classes and Interfaces?
• Is it possible to implement multiple inheritance in Java?
• What is serialization? How do you implement it?
• What are anonymous classes?
• What does it means to say that a String is immutable?
• What is the difference between method overloading and method overriding?
• What are the access modifiers you know? What does each one do?
• Do objects get passed by reference or value in Java? Elaborate on that.
• What the difference between local, instance and class variables?
• What is Dependency Injection?
• What does the static word mean in Java? Can a static method be overridden in Java?
• When is a static block run?
• What is reflection?
• How does the try{} catch{} finally{}
• What is garbage collection? How does it work?
• What is memory leak and how does Java handle it?
• What does the keyword synchronized mean?
• Explain Generics in Java

Web Development

• What is the difference between a GET and POST request?
• What is a URI?
• Differenciate between a client and host.
• What is the difference between HTTP and HTTPS?
• Point out these components(query, host, port, protocol, path ) in the following URL https://127.0.0.1:4200/login/a=bx?c
• What is an Internet Protocol?

Android

• What are the four main components of an Android Application?
• What is the purpose of a package name?
• What is the purpose of Android Virtual Device?