The java stack and heap differences are described in detail

java stack and heap differences

1, garbage collection mechanism only ACTS on heap memory, and has nothing to do with stack memory;

2. Stack: the access speed of stack stack is faster than that of the heap, and it saves the reference values of local variables and objects efficiently

3. Heap: save large variables

4. There is a very important particularity of the stack, that is, the data in the stack can be Shared

When the compiler processes int a = 3, it first creates a reference to a in the stack, and then looks for the value 3 in the stack. If it doesn't, it stores 3 in the stack.

The same is true for b = 3, where the compiler simply creates the b variable and points it to 3 (to save space) because it stored the 3.
This is when a and b point to 3 at the same time, but does not affect their use. If I define a = 4; , then 4 needs to be stored in memory and pointed from a to 4. The modification of a value will not affect b value.

 Memory partition: 


1 Register. 
2 , the local method area. 
3 , method area. 
4 , stack memory. 
  All you store are local variables. 
  And the scope of the variable 1 Once finished, the variable is automatically released. 
5 , heap memory. 
  The storage is arrays and objects ( An array is an object )  Anyone who new Build in the heap. 
  Features: 
 1 , each 1 Each entity has a first address value. 
 2 , each in heap memory 1 Each variable has a default initialization value, depending on the type. The integer is 0 , the decimal 0.0 or 0.0f . boolean false char '\u0000'
 3 , garbage collection mechanism. 

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