CODEWITHSUNDEEP
javaarraysstack
Tyler Carr
Tyler Carr

Reputation: 45

Java array stack, printing contents of stack from top to bottom

I'm relatively new to programming and can't sort this one out. I have an array stack that I have just set up. I'm trying to create a toString() method that returns the contents of the array listed from top to bottom of the stack.

For example, the array contains elements...[1,2,3,4,5] with '5' being the top of the stack and '1' being the bottom. I want to return '5', followed by a new line, then '4', etc. until I reach '1.'

The code I have so far for the toString method is:

/**
 * Returns a string representation of this stack. The string has
 * form of each element printed on its own line, with the top most              
 * element displayed first, and the bottom most element displayed
 * last.
 * If the list is empty, returns the word "empty".
 * @return a string representation of the stack
 */
public String toString()
{
    String result = "";
    for (int scan = 0; scan < top; scan++)
        result = result + stack[scan].toString() + "\n";
    return result;
}

Currently, this is returning the contents of the stack from bottom to top, not top to bottom. Any suggestions?

Upvotes: 1

Views: 2462

Answers (3)

SkyMaster
SkyMaster

Reputation: 1323

Try this: 

public String toString(){
    StringBuilder sb = new StringBuilder();
    for(int i=stack.size()-1;i>=0;i--) {
        sb.append(stack.get(i)).append("\n");
    }
    return sb.length()>0 ? sb.toString(): "empty";  
}

Upvotes: 0

Kaspar Wiess
Kaspar Wiess

Reputation: 1

According to the specification's comment, the code should verify if the array is empty:

public String toString(){

    String result = "";
    for (int scan =stack.length-1 ; scan >= 0; scan--) {
         if(stack[scan] != null ) {
             result = result + stack[scan].toString() + "\n";
         }
    }

    if( result.length() == 0) {
        return "empty";
    } else {
        return result;
    }

}

Upvotes: 0

Abdullah Asendar
Abdullah Asendar

Reputation: 604

replace your toString method with : 

 public String toString(){
     String result = "";
     for (int scan =top-1 ; scan >= 0; scan--)
         result = result + stack[scan].toString() + "\n";
     return result;
 }

Upvotes: 2

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