stack vs heap code example

Example 1: heap vs stack memory

Whenever an object is created, it’s always stored in the Heap space, and stack
memory contains the reference to it. Stack memory only contains local
primitive variables and reference variables to objects in heap space.
Objects stored in the heap are globally accessible whereas stack memory can’t 
be accessed by other threads.
Memory management in stack is done in LIFO manner whereas it’s more complex in
Heap memory because it’s used globally.
Stack memory is short-lived whereas heap memory lives from the start till the
end of application execution.
Heap memory is used by all the parts of the application, stack memory is used
only by one thread of execution.
When stack memory is full, Java runtime throws
java.lang.StackOverFlowError When heap memory is full, it throws
java.lang.OutOfMemoryError: Java Heap Space error.
Stack memory is faster than heap memory.

Example 2: heap memory vs string pool

String uses a special memory location
to reuse of String objects called String Constant Pool.
String objects created without
the use of new keyword are stored in the
String Constant Pool part of the heap.
It doesn't create the same string object
if there is already string constant in the pool.


String str = new String("");
String str2 = "";

Str goes to heap memory
str2 goes to string pool location

They both immutable and they save in different 
memory location.