Stack problem

[Clown]

Hi everyone. I am trying to write a simple method,which prints all of the elements of a stack.

import java.util.*;

public class Stackcalculator extends java.util.Stack

{
public void show(){
private LinkedList<Double> stack = new LinkedList<Double>();
double []b=new double[100];
int i=0;
while (stack.empty()==false){
b[i]=stack.pop();
System.out.println(""+b[i]);
i++;
}
}
}

The problem is that I get an error message saying that "method empty is not recognized" although the method is actually in the java class stack. Any ideas what I am doing wrong? I am using Bluej.

[gcalvin]

Your stack variable is not a Stack, it's a LinkedList<Double>. LinkedList has no empty() method.

-Gary-

[Clown]

Thanx. Any ideas how i can actually do it?

[JosAH]

Thanx. Any ideas how i can actually do it?

How about reading the API documentation for the LinkedList class and the List interface? Alsways read and study first before you start guessing.

kind regards,

Jos

[gcalvin]

It's not at all clear what you're trying to do, but if it's really "print all the elements of a stack" (in which case, what are we trying to do with LinkedList<Double>?) then it would be good to take a look at the documentation for java.util.Stack. Hint: do you know how to print all the elements of a Vector?

-Gary-

[JosAH]

java.util.Stack

I personally find that a stack on steroids because it extends the Vector class and inherits all of its methods that are none of a stack's business. Its a typical example of a too strong super class and a too weak sub class. But it indeed is a stack ...

kind regards,

Jos

[gcalvin]

I personally find that a stack on steroids because it extends the Vector class and inherits all of its methods that are none of a stack's business. Its a typical example of a too strong super class and a too weak sub class. But it indeed is a stack ...

kind regards,

Jos

I agree, and I don't see what's useful about printing all the elements on a stack in what appears to be a stack-based calculator app (guessing from the class name) but at least it's easy to do when your Stack is a Vector.

-Gary-

[JosAH]

I agree, and I don't see what's useful about printing all the elements on a stack in what appears to be a stack-based calculator app (guessing from the class name) but at least it's easy to do when your Stack is a Vector.

The OP would be a good sport if s/he'd use a second stack like this:

while (!stack1 is empty) {
   T elem= pop from stack1
   // <--- either print elem here
   push elem on stack2
}
while (!stack2 is empty) {
   T elem= pop from stack2
   // <--- or print elem here
   push elem on stack1
}

kind regards,

Jos

[gcalvin]

The OP would be a good sport if s/he'd use a second stack like this:

while (!stack1 is empty) {
   T elem= pop from stack1
   // <--- either print elem here
   push elem on stack2
}
while (!stack2 is empty) {
   T elem= pop from stack2
   // <--- or print elem here
   push elem on stack1
}

kind regards,

Jos

True, as long as we're not worried about thread safety (which we probably aren't in this app).

-Gary-

[JosAH]

True, as long as we're not worried about thread safety (which we probably aren't in this app).

Multiple threads won't hurt much either because all the surgery is done in the Vector class and those methods are all synchronized ;-)

kind regards,

Jos