以下哪一项是 java 中更好的编程实践来调用用户定义的 class 中存在的方法？

Question

Stack newStack = new Stack();
newStack.push(0);

OR

Stack.push(0);

Note: Here Stack is a user defined class to implement concept of stack manually in java and not the predefined one.

Answer 1

This allows having multiple stacks for different purposes.

Stack newStack = new Stack();
newStack.push(0);

We can have only one stack when using this.

Stack.push(0);

I prefer the first one as it allows initializing multiple stacks at the same time which the second way can't do.

Answer 2

In the first example, push is a non-static method of the Stack class. In order to use the push method, you have to create an instance of the Stack class.

Stack newStack = new Stack();
newStack.push(0);

The equivalent code with an anonymous instance would be:

new Stack().push(0);

which would be kind of useless in this case, since you're eventually going to want to pop the stack you created.

In the second example, push is a static method of the Stack class.

Stack.push(0);

Nandu Raj is correct in his answer in that you can only have one Stack in your application, rather than more than one with the non-static push method.

Creating and using non-static methods is generally a better programming practice, although there are cases, like the Java Math class, where static methods work better.