Core Java

Java Question - 1 What is the difference between private, protected, and public

Java Question - 2 what’s the difference between an interface and an abstract class 

Java Question - 3 How you can force the garbage collection

Java Question - 4 What's the difference between constructor and normal methods?

Java Question - 5 Can you call one constructor from another if a class has multiple constructor

Java Question - 6 Explain the usage of Java packages

Java Question - 7 Explain in your own words the "bottom line " benefits of the use of an interface.

Java Question - 8 What are some advantages and disadvantages of Java Sockets?

Java Question -9 Explain the usage of the keyword transient?

Java Question - 10 What's the difference between the methods sleep () and wait ()

Java Question - 11 What would you use to compare two String variables - the operator == or the method equals()?

Java Question - 12 Why would you use a synchronized block vs. synchronized method?

Java Question - 13 What access level do you need to specify in the class declaration to ensure that only classes from the same directory can access it?

Java Question - 14 Can an inner class declared inside of method access local variables of this method?

Java Question - 15 What can go wrong if you replace && with & in the following code: String a=null; if (a! =null && a.length ()>10) {...}

Java Question - 16 What's the main difference between a Vector and an Array List?

Java Question - 17 Describe the wrapper classes in Java.

Java Question -18 How could Java classes direct program messages to the system console, but error messages, say to a file?

Java Question -19 How do you know if an explicit object casting is needed?

Java Question -20 Can you write a Java class that could be used both as an applet as well as an application?

Java Question - 21 If a class is located in a package, what do you need to change in the OS environment to be able to use it?

Java Question - 22 What's the difference between J2SDK 1.5 and J2SDK 5.0?

Java Question - 23 Does it matter in what order catch statements for FileNotFoundException and IOExceptipon are written?

Java Question - 24 Name the containers which uses Border Layout as their default layout?

Java Question - 25 Which of the two Java collections should you use:

Java Question - 26 When should the method invokeLater()be used?

Java Question - 27 How can a subclass call a method or a constructor defined in a superclass?

Java Question - 28 What do you understand by Synchronization?

Java Question - 29 What's the difference between a queue and a stack?

Java Question - 30 You can create an abstract class that contains only abstract methods. On the other hand, you can create an interface that declares the same methods. So can you use abstract classes instead of interfaces?

Java Question - 31 If you're overriding the method equals() of an object, which other method you might also consider?

Java Question - 32 What is Collection API?

Java Question - 33 How would you make a copy of an entire Java object with its state?

Java Question - 34 How can you minimize the need of garbage collection and make the memory use more effective?

Java Question - 35 There are two classes: A and B. The class B need to inform a class A when some important event has happened. What Java technique would you use to implement it?

Java Question - 36 Explain the Encapsulation principle.

Java Question - 37 Explain the Inheritance principle.

Java Question - 38 Explain the Polymorphism principle.

Java Question - 39 Is Iterator a Class or Interface? What is its use?

Java Question - 40 Explain the user defined Exceptions?

Java Question - 41 What is OOPS?

Java Question - 42 Program of Equal and its result

Java Question - 43 Name the containers which uses Border Layout as their default layout?

Java Question - 44 What do you understand by Synchronization?