Java streams compare property is equal between two lists and return true or false

class Pair {
    String key;
    String value;
}

List<Pair> list1 = Stream.of(
        new Pair("key1", "value1"),
        new Pair("key2", "value2")
    )
    .collect(Collections.toList());

List<Pair> list2 = Stream.of(
        new Pair("key1", "value2"),
        new Pair("key2", "value3")
    )
    .collect(Collections.toList());

I want to perform some changes in the values in list2 and then compare it to list1.

I want to check if the property key has not changed in list2 for all items in the list in comparison with list1 . Only value property can be changed in list2.

And that the number of items in list2 is the same as list1 list1.size() = list2.size()

I am trying to write a stream that returns a boolean but somewhere I must have been mistaken

list1.stream()
    .allMatch(pair2->  list2.stream()
        .anyMatch(pair->pair.getKey().equals(pair2.getKey())));
    // Need to add list size() comparison too

Update:
I managed to write a stream like this, junit tests seem to work, although it does not compare items at the same index as ernest_k's answer.

   list1.stream()
        .allMatch(pair -> list2.stream()
            .anyMatch(pair2-> pair.getKey().equals(pair2.getKey()) ) && list1.size()== list2.size()
            ));

You can use:

boolean result = list1.size() == list2.size() && 
        IntStream.range(0, list1.size())
		    .allMatch(i -> list1.get(i).getKey().equals(list2.get(i).getKey()));

As you have to compare the lists element by element, you can't use a nested stream as that (like in your example), would simply do a cartesian join and return true if each list1 element has any list2 element with the same key (whereas you want that comparison to be index-aware)

You may consruct a lookup table to refer original keys.

public static compareStates(List<Pair> original, List<Pair> current){
    
    	Map<String,Pair> lookupTable= original.stream.collect(Collectors.toMap(x ->x.key,x->x));
    
    	boolean hasElementChanged = current.stream().filter(pair -> !lookupTable.containsKey(pair.key)).count() >0;
    
    	boolean hasCountChanged = original.length !=current.length;
    
    	return hasCountChanged || hasElementChanged;
    }