Java Questions

Array is collection of same data type. Array size is fixed, It cannot be expanded.

But ArrayList is a growable collection of objects.ArrayList is a part of Collections Framework and can work with only objects.

ClassName refName = new ClassName();

or

ClassName refName;

refName = new ClassName();

JAR files are java's version of ZIP files. In fact, JAR uses the ZIP file format.

uses:

- to compress a number of . class files into one file

- to make a java executable JAR file.

By using method.

The method used to get the data is called getter method.

This is a keyword and used as reference to Current object address in java. 

It means by using which object the method is called that object hashcode is stored inside the 'this'.

:: is the scope resolution operator. When local variable and global variable are having same name, local variable gets the priority. C++ allows flexibility of accessing both the variables through a scope resolution operator

A method declared as final can't be overridden. A sub-class can't have the same method signature with a different implementation.

Variables declared within a method are local variables. Variables declared within the class are member variables.  Variables declared within the class with static modifier are class variables