Creating multiple objects by one type only

In real-time, we need different objects of a class in different methods. Creating a number of references for storing them is not a good practice and therefore we declare a static reference variable and use it whenever required. In this case, wastage of memory is less. The objects that are not referenced anymore will be destroyed by Garbage Collector of java. Example:

$\begin{lstlisting} Test test = new Test(); test = new Test(); \end{lstlisting}$
In inheritance system, we use parent class reference variable to store a sub-class object. In this case, we can switch into different subclass objects using same referenced variable. Example:

$\begin{lstlisting} class Animal {} \par class Dog extends Animal {} class Cat e... ...obj = new Dog(); \par // using Cat object obj = new Cat(); } \end{lstlisting}$