ArrayList is most widely used collections API for storing the list of objects. This class is equivalent to Vector, except that it is unsynchronized. Look at the below important points about the class ArrayList. It allows null values It stores the duplicate elements The size of the list is grows dynamically when more elements are …
Difference Between Throw and Throws in Exception Handling
When you are working with exception handling in Java, use of throw and throws may confuse you if you not familiar with the exception handling. Both are important keywords used frequently used in handling the exceptions. Throw is used for explicitly throwing an exception. Throw attribute in method signature, is a hint to the compiler …
Try, Catch and Finally in Exception Handling
The basic procedure to handle the exception is to use the try-catch block. If you want to put any code that would cause a exception, then write that piece of code inside the try-catch block. If you expect multiple type of exceptions in the same block, then you can write more than one catch block …
Constructor in Java
Constructors are special type of methods that are invoked at the time of creating the objects. If you use new keyword for creating the object, the constructors are called. There are certain restrictions imposed on these special type of methods. Constructors should have the same name as class name Constructors should not have any return …
Method Overloading Vs Overriding in Java
In our previous tutorials we have explained about the method overloading and method overriding in Java. Read those tutorials for the more explanations. This tutorial highlights the only differences and when we have to use both the concepts. Both the concepts are based on the polymorphism in Java. Look at the below table for the …
Method Overriding in Java
Method Overriding is concept of overriding a same method in the child class. This is fall under the dynamic polymorphism or run time polymorphism. A method defined in the parent class is considered as the common behaviour and the child classes are expected to override the common behaviour with own implementation. There are multiple restrictions enforced …
Instanceof Operator
Instanceof Operator is important for writing the condition to check if a particular variable reference is of specific type / class. In short it is type checking condition. This operator returns true or false depends on the condition output. It always return false if you compare null value with any class. Lets look at an …
Instance Initializer in Java
Instance initializer in Java is used for initializing the instance variables inside a class. It is a simple block without any modifiers used inside any class. If you declare a instance variable with value, then this value can be overridden in the instance initializer or in the constructor. The order of the execution as follows: …