Map.Entry: How to use it?

Question

I\'m working on creating a calculator. I put my buttons in a HashMap collection and when I want to add them to my class, which extends JPanel, I do

Answer 1

Map.Entry is a key and its value combined into one class. This allows you to iterate over Map.entrySet() instead of having to iterate over Map.keySet(), then getting the value for each key. A better way to write what you have is:

for (Map.Entry entry : listbouton.entrySet())
{
  String key = entry.getKey();
  JButton value = entry.getValue();

  this.add(value);
}

If this wasn't clear let me know and I'll amend my answer.