To know what is the difference between them and how they work, we need to take a look at there holder classes.
Keep in mind that the Stack class extends the Vector class. Disregard other classes if you want.
OK, assume that we have this in the main method
Stack<Object> s = new Stack<Object>();s.push();
It calls the push method in the Stack class, which looks like this…
It then calls public addElement() in the Vector class and returns the item that we just pushed. To be able to do this for example…
Object obj = s.push(new Object());
As you can see, it calls another method in the Vector Class.
If you wonder what synchronized do, it locks an object, in this case, a method, from any shared resources. This is usually happening because of multi-threading stuff.
Finally, it increases the size of the stack and pushes the element.
s.add();
It calls add() in the Stack Class,
does this look familiar ???
Yes, it is.
This is the same as addElement() that s.push() calls, except it, is always returning true.
It then calls add() method in the Vector Class. ‘Image 2’
To Conclude
s.push() -> public addElement() -> private add()always
but
s.add() -> public add() -> private add()
This is just a method call … Both ways they lead to the call of the private method .add() witch add the element to the stack
The only difference between these calls is the return values.
s.push() return the object you are pushing.
s.add() always return true.
Thanks for reading
