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Thread: Some of my methods don't run properly

  1. #1
    Junior Member pyler's Avatar
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    Default Some of my methods don't run properly

    The reverse stack method in my LinkedStack class is supposed to return a reversed copy of the stack object that uses it. So when I populate somestack with strings as below, and do somestack.reversed(); System.out.println(somestack); should print a reversed version of somestack. Instead all I get is an empty stack when I run the code below.

    LinkedStack<String> somestack=new LinkedStack<String>();
    somestack.push("Decide");
    somestack.push("Heart");
    somestack.push("Fears");
    somestack.push(Strength"");
    somestack.push("Potluck");
    System.out.println("Stack was"+somestack);
    somestack.reversed();
    System.out.println("Stack is reversed: "+somestack);

    Output
    Potluck
    Strength
    Fears
    Heart
    Decide
    Stack is reversed:

    Reversed should print whole stack beginning with Decide
    Can any one find an error in my code?
    import java.util.NoSuchElementException;
    //import java.util.Stack;
    public class LinkedStack<T>{
    	@SuppressWarnings("hiding")
    	public class Node<>{
    		private T info;
    		private Node<T> next;
    		public Node(T info,Node<T>next){
    			this.info=info;
    			this.next=next;
    		}//Node constructor
    	public void setInfo(T info){this.info =info;}
     
    	public T getInfo(){return info;}
     
    	public void setNext(Node<T> newNext){this.next=next;}
     
    	public Node<T> getNext(){return next;}
    }//end of node
     
    private Node<T> top=null;//whenever newFS created top=null
     
    public void push(T element){//this push
    	top=new Node<T>(element,top);
    	}
     
    public void push(LinkedStack<T> stack){
    	//int SIZE = stack.size();
    	while(!(stack.empty()))//for(int i=0;i<SIZE;i++){
    		this.push(stack.pop());}}
     
    public T peek(){
    	if(top==null){throw new NoSuchElementException();}
    	else
    	     return top.getInfo();
    	}
     
    public T pop(){
    		T element=peek();
    		top=top.next;
    		return element;
    	}
     
    public boolean isEmpty(LinkedStack<T> s){
    	return(top==null);
    }
     
    int count=0;
    public int size(){
    	count++;
    	return count;
    }
     
     
    public LinkedStack<T> reversed()
    {
    	LinkedStack<T> revertStack = new LinkedStack<T>();
    	//int LENGTH = this.size();
    	while(!(this.empty()))//for(int j=0;j<LENGTH;j++)
              {
                  revertStack.push(pop());
              }
    	return this;//end of method
    }
     
    //Returns a string representation of this stack
    public String toString(){
    	String result="";
    	Node<T> current=top;//set the current node to top
    	while(current !=null){//while link isn't null
    		result=result+(current.getInfo()).toString()+"\n";
    		current=current.getNext();
    	}
    	return result;//return result
    }
    }//end of LinkedStack


  2. #2
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    Default Re: Some of my methods don't run properly

    Your code contains quite a number of syntax errors, such as unclosed strings, braces and typed arguments. Then you also keep refering to this.empty() which doesn't exist. So instead of working 1 by 1 for hours with you, heres a cleaned up version of your code, which works fine. NOTE: no logic was changed, only syntax.

    import java.util.NoSuchElementException;
     
    //import java.util.Stack;
    public class LinkedStack<T> {
     
    	public static void main(String[] args){
    		LinkedStack<String> somestack=new LinkedStack<String>();
    		somestack.push("Decide");
    		somestack.push("Heart");
    		somestack.push("Fears");
    		somestack.push("Strength");
    		somestack.push("Potluck");
    		System.out.println("Stack is: \n"+somestack);
    		System.out.println("Stack is reversed: "+somestack.reversed());
    	}
     
    	@SuppressWarnings("hiding")
    	public class Node<T> {
    		private T info;
    		private Node<T> next;
     
    		public Node(T info, Node<T> next) {
    			this.info = info;
    			this.next = next;
    		}// Node constructor
     
    		public void setInfo(T info) {
    			this.info = info;
    		}
     
    		public T getInfo() {
    			return info;
    		}
     
    		public void setNext(Node<T> newNext) {
    			this.next = next;
    		}
     
    		public Node<T> getNext() {
    			return next;
    		}
    	}// end of node
     
    	private Node<T> top = null;// whenever newFS created top=null
     
    	public void push(T element) {// this push
    		top = new Node<T>(element, top);
    	}
     
    	public void push(LinkedStack<T> stack) {
    		// int SIZE = stack.size();
    		while (!(stack.isEmpty(this))) {
    			this.push(stack.pop());
    		}
    	}
     
    	public T peek() {
    		if (top == null) {
    			throw new NoSuchElementException();
    		} else
    			return top.getInfo();
    	}
     
    	public T pop() {
    		T element = peek();
    		top = top.next;
    		return element;
    	}
     
    	public boolean isEmpty(LinkedStack<T> s) {
    		return (top == null);
    	}
     
    	int count = 0;
     
    	public int size() {
    		count++;
    		return count;
    	}
     
    	public LinkedStack<T> reversed() {
    		LinkedStack<T> revertStack = new LinkedStack<T>();
    		// int LENGTH = this.size();
    		while (!(this.isEmpty(this)))// for(int j=0;j<LENGTH;j++)
    		{
    			revertStack.push(this.pop());
    		}
    		return revertStack;// end of method
    	}
     
    	// Returns a string representation of this stack
    	public String toString() {
    		String result = "";
    		Node<T> current = top;// set the current node to top
    		while (current != null) {// while link isn't null
    			result = result + (current.getInfo()).toString() + "\n";
    			current = current.getNext();
    		}
    		return result;// return result
    	}
    }// end of LinkedStack
    Please use [highlight=Java]//code goes here...[/highlight] tags when posting your code

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