What is the purpose of using an Integer object pool in applications?

The purpose of using an Integer object pool in Java is to reduce the cost of creating new objects and to improve performance by reusing frequently used values.

Java automatically caches Integer objects in the range from -128 to 127 (by default). When creating an Integer within this range, an existing object from the pool is returned instead of creating a new one.

This saves memory and reduces the load on the garbage collector, especially when numbers in this range are used frequently.

Example:

Integer a = Integer.valueOf(100);
Integer b = Integer.valueOf(100);
System.out.println(a == b); // true, objects from the pool

Integer c = Integer.valueOf(200);
Integer d = Integer.valueOf(200);
System.out.println(c == d); // false, different objects

Thus, the Integer object pool optimizes the handling of frequently used numeric values.