How to Iterate through two ArrayLists Simultaneously? [duplicate]

Question

I Have Two Array Lists, Declared as:

ArrayList<JRadioButton> category = new ArrayList<JRadioButton>(); ArrayList<Integer> cat_ids = new ArrayList<Integer>(); 

Both of the these fields contain exactly, the Same No of Values, which are infact corresponding in Nature.

I know I can iterate over one of the loops like this:

for(JRadioButton button: category) {      if(button.isSelected())      {            buttonName = button.getName();            System.out.println(buttonName);             } } 

But, I would like to iterate over both the LISTS simultaneously. I know they have the exact same size. How do I Do that?

Answer 1

You can use Collection#iterator:

Iterator<JRadioButton> it1 = category.iterator(); Iterator<Integer> it2 = cats_ids.iterator();  while (it1.hasNext() && it2.hasNext()) {     ... } 

Answer 2

java8 style:

private static <T1, T2> void iterateSimultaneously(Iterable<T1> c1, Iterable<T2> c2, BiConsumer<T1, T2> consumer) {     Iterator<T1> i1 = c1.iterator();     Iterator<T2> i2 = c2.iterator();     while (i1.hasNext() && i2.hasNext()) {         consumer.accept(i1.next(), i2.next());     } } // iterateSimultaneously(category, cay_id, (JRadioButton b, Integer i) -> {     // do stuff... });