Stack keeps pushing null instead of String value Java

Question

I'm working on a project where I have to push String values into a stack. Whenever I push the first value into the stack it goes in with no problem, but after that any element I push turns into 'null'. Here's some of my sample code

public void push (E element){

    if( isEmpty() ){
        stack = (E[]) new Object[1];
        stack[0] = element;
    } else {

        int size = stack.length + 1;
        E[] tmpStack = (E[]) new Object[size];

        for (int i = 0; i < stack.length - 1; i++ ) {

        tmpStack[i] = stack[i];
        }

        stack = tmpStack;

        tmpStack = null;

        stack[size - 1] = element;
        }

Here's how I've been calling the method:

String elementArray[] = str.split(",");

    for(int i = 0; i < elementArray.length; i++){
        stack.push(elementArray[i]);
    }

jkinkead · Accepted Answer · 2018-04-15 04:12:30Z

2

You have an off-by-one error. You're not copying the last element out of your source stack.

This:

for (int i = 0; i < stack.length - 1; i++ ) {

should be:

for (int i = 0; i < stack.length; i++ ) {

Bonus tip: Consider using System.arraycopy.

answered Apr 15, 2018 at 4:12

jkinkead

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