Iterating through List but it only shows last item

Question

What I am trying to achieve is have one JLabel to display multiple items from a List.

I have defined the list as below but when I test the code

Answer 1

Your current code always overrides the current text in the JPanel, and it does that so fast, that you don't see it. Instead of using the Iterator, get the next item in the list by defining an int variable that gets incremented every press.
The index variable is a public int in this example:

 jLabel1.setText(strings.get(index));
 if (index < strings.size()-1) 
        index++;

No loops, that's everything needed in your method.

Answer 2

In order to locate next string from collection, you need somehow know about current item.

One approach is to store index (or iterator) in a field:

List<String> strings=<...>
// 1. store index    
int sentenceIndex = 0; 
// 2. store iterator. You could get ConcurrentModificationException if change list and then use iterator.
Iterator<String> iterator = strings.getIterator();
private void buttonpressActionPerformed() { 
// 1. use index. 
if (sentenceIndex < strings.size()-1) { // avoid IndexOutOfBoundException
  String nextSentence = strings.get(sentenceIndex++);
}
// 2. use iterator
if (iterator.hasNext()) {
  String nextSentence = iterator.next();
}

But in fact you don't need to store something:

// 3. calculate current index
String currentSentence = jLabel1.getText();
int currentIndex = strings.indexOf(currentSentence);
int nextIndex = incrementIndex(currentIndex);
String nextSentence = strings.get(nextIndex );

Note that I suggest new method incrementIndex. In it you could add not only lenght check but also jumping from last element to the first or just random selecting.

Each method has pro and contras:

1. index require boundary checks

2. iterator limits list updating

3. index calcucaliton also require boundary checks and label1 should have correct initial value

   I would prefer storing index but it's your choice