What is static in java
[
]
Static means one per class, not one for each object no matter how many instance of a class might exist. This means that you can use them without creating an instance of a class.Static methods are implicitly final, because overriding is done based on the type of the object, and static methods are attached to a class, not an object. A static method in a superclass can be shadowed by another static method in a subclass, as long as the original method was not declared final. However, you can't override a static method with a nonstatic method. In other words, you can't change a static method into an instance method in a subclass.
Choose your rating:
Post Ans. View More Ans.
What is an abstract class
[
]
Abstract class must be extended/subclassed (to be useful). It serves as a template. A class that is abstract may not be instantiated (ie, you may not call its constructor), abstract class may contain static data. Any class with an abstract method is automatically abstract itself, and must be declared as such.
A class may be declared abstract even if it has no abstract methods. This prevents it from being instantiated.
Choose your rating:
Post Ans. View More Ans.
What is an Iterator?
[
]
Some of the collection classes provide traversal of their contents via a java.util.Iterator interface. This interface allows you to walk through a collection of objects, operating on each object in turn. Remember when using Iterators that they contain a snapshot of the collection at the time the Iterator was obtained; generally it is not advisable to modify the collection itself while traversing an Iterator.
Choose your rating:
Post Ans. View More Ans.
What is the difference between a constructor and a method?
[
]
A constructor is a member function of a class that is used to create objects of that class. It has the same name as the class itself, has no return type, and is invoked using the new operator.
A method is an ordinary member function of a class. It has its own name, a return type (which may be void), and is invoked using the dot operator.
Choose your rating:
Post Ans. View More Ans.
Difference between Swing and Awt?
[
]
AWT are heavy-weight componenets. Swings are light-weight components. Hence swing works faster than AWT.
Choose your rating:
Post Ans. View More Ans.
Difference between Vector and ArrayList?
[
]
Vector is synchronized whereas arraylist is not.
Choose your rating:
Post Ans. View More Ans.
Difference between HashMap and HashTable?
[
]
The HashMap class is roughly equivalent to Hashtable, except that it is unsynchronized and permits nulls. (HashMap allows null values as key and value whereas Hashtable doesnt allow). HashMap does not guarantee that the order of the map will remain constant over time. HashMap is unsynchronized and Hashtable is synchronized.
Choose your rating:
Post Ans. View More Ans.
What is HashMap and Map?
[
]
Map is Interface and Hashmap is class that implements that.
Choose your rating:
Post Ans. View More Ans.
What are pass by reference and passby value?
[
]
Pass By Reference means the passing the address itself rather than passing the value. Passby Value means passing a copy of the value to be passed.
Choose your rating:
Post Ans. View More Ans.
Explain different way of using thread?
[
]
The thread could be implemented by using runnable interface or by inheriting from the Thread class. The former is more advantageous, 'cause when you are going for multiple inheritance..the only interface can help.
Choose your rating:
Post Ans. View More Ans.
