Reuse

Data Structures and Algorithms with Object-Oriented Design Patterns in Java

Reuse

Sometimes, a Java program will create many objects which are used only once. For example, a program may create an object in the body of a loop that is used to hold ``temporary'' information that is only required for the particular iteration of the loop in which it is created. Consider the following:

for (int i = 0; i < 1000000; ++i)
{
    SomeClass obj = new SomeClass (i);
    System.out.println (obj);
}

This creates a million instances of the SomeClass class and prints them out. If the SomeClass class implements a setInt method, we can reuse an a single object instance like this:

SomeClass obj = new SomeClass ();
for (int i = 0; i < 1000000; ++i)
{
    obj.setInt (i);
    System.out.println (obj);
}

Clearly, by reusing a single object instance, we have dramatically reduced the amount of garbage produced.