CODEWITHSUNDEEP
javapass-by-referencepass-by-value
pranav shukla
pranav shukla

Reputation: 353

Reference to Classes in Java

I was doing inorder traversals when in the solution I came across the following lines:

stack.push(current);
current = current.left;

Now my question is that when I push current into the stack and make current = current.left; then will the node that is there within the stack also change to current.left? In my case, the current in the stack still points to the original current but the current variable does point to current.left. Why is this?

Upvotes: 1

Views: 66

Answers (5)

Andrew
Andrew

Reputation: 49606

stack.push(current);

enter image description here

current = current.left;

enter image description here

Upvotes: 1

Sergei Rybalkin
Sergei Rybalkin

Reputation: 3453

Java is pass-by-value. You pass the value of reference to object. Changing the reference will not affect copied reference value in stack.

Upvotes: 0

user6781230
user6781230

Reputation:

You're changing what the variable "current" references, but the object in the Stack won't be changed just because your variable is now referencing a different object.

/* Misread the question ignore this...

If you're asking if the changes you make to the object 'current' will also have the same effect as the current object pushed to the stack. The short answer is yes.

You're pushing the object, not a clone. The object never changes or is cloned, and putting something in a Stack is just another way including your variable declaration to reference the object in memory.

The same applies to HashMap, ArrayList, etc. */

Upvotes: 1

V-master
V-master

Reputation: 2167

just look at it from other perspective: in C/C++ you have pointers. All variables in java should be threated like those pointers. When you are calling a method, in fact you pass the new pointer to given object, rather than reference to it. With = you are just overriding value of pointer with pointer to new object, and old object still exists till garbage collector will collect it.

Upvotes: 0

OldCurmudgeon
OldCurmudgeon

Reputation: 65811

At a guess - because stack.push(current) is taking a copy of current for the stack.

Upvotes: 0

Related Questions