Adding char from string to stack

Question

I am trying to add the chars from a string in a textbox into my Stack,

here is my code so far:

String s = txtString.getText();
Stack myStack = new LinkedStack();

  for (int i = 1; i <= s.length(); i++)
{
    while(i<=s.length())
        {
         char c = s.charAt(i);
        myStack.push(c); 
        }
       System.out.print("The stack is:\n"+ myStack);
}

My push and pop method from LinkedStack

public void push(Object item){
  top = new ListNode(item, top); 
}

public void pop(){
  if(isEmpty())
    throw new StackUnderflowException("Nothing removed-stack is empty");
  else
   top = top.getNext();
}

getnext() method comes from another package called listnodes

public ListNode getNext() {
    return nextNode; // get next node
} // end method getNext

when I change the print to + c, all the chars from my string prints, but when it is myStack it now gives me a string out of index range error.

Does anybody know what I am missing?

You haven't given us the code for `LinkedStack`, so how can we help? — Oliver Charlesworth, Sep 20 '11 at 00:05
Shouldn't you print your stack outside the loop? Also, you would need to "pop" the stack in order to get the reverse string. — Usman Saleem, Sep 20 '11 at 00:07
+1 @ Oli Charlesworth. It should be just Stack if you are using Java's own implementation of Stack class. — Usman Saleem, Sep 20 '11 at 00:09

score 2 · Answer 1 · answered Feb 27 '19 at 23:42

2

String a = "String";
Stack<Character> stack = new Stack<>();
a.chars().forEach(c -> stack.push((char)c));

answered Feb 27 '19 at 23:42

Fernando Escalona

31
2

1

Hi, welcome to Stack Overflow. When answering a question that already has a few answers, please be sure to add some additional insight into why the response you're providing is substantive and not simply echoing what's already been vetted by the original poster. This is especially important in "code-only" answers such as the one you've provided. – chb Feb 28 '19 at 00:01

Mike Samuel · Accepted Answer · 2011-09-20T00:26:43.950

2

LinkedStack.toString is not terminating. You're probably missing a base case there. Add a proper base case to it, and/or make sure your stack doesn't end up cyclic due to a bug in push or pop, and your print should work fine.

Your push implementation looks ok, pop doesn't assign top, so is definitely broken.

edited Sep 20 '11 at 00:26

answered Sep 20 '11 at 00:08

Mike Samuel

118,113
30
216
245

the pop uses getNext() which assigns the top to nextNode does it not? – Peerkon Sep 20 '11 at 00:31
@Peerkon, no it doesn't. Nor should it. A `get` method should not go modifying things. Only methods named with a verb that implies change, such as `set` or `replace`, should mutate data. And you defined `getNext` correctly as just `return nextNode`. There's no `top =` in there. – Mike Samuel Sep 20 '11 at 01:47

score 0 · Answer 3 · answered Apr 14 '17 at 23:22

String s = txtString.getText();
Stack myStack = new LinkedStack();

for (int i = 1; i <= s.length(); i++)
{
    while(i<=s.length())
        {
            char c = s.charAt(i);
            myStack.push(c); 
         }
     System.out.print("The stack is:\n"+ myStack);
}

Your for loop should start at 0 and be less than the length. Another error is that the while loop runs infinitely since 1 will always be less than the length or any number for that matter as long as the length of the string is not empty. So in your case I would simply remove the while statement and just do it all in the for loop, after all your for loop will only run as many times as there are items in your string.

Fixed version that does what you want it to do.

 for (int i = 0; i < s.length(); i++)
    {
          char c = s.charAt(i);
          myStack.push(c); 

          System.out.print("The stack is:\n"+ myStack);
    }

Adding char from string to stack

3 Answers3