How to compare two lists of custom objects for some properties using streams in Java?-CodePudding

What is the best way to compares the items of two lists by (only) some of their properties?

public class A {
    private String type;
    private String value;
    private String foo;
    private String bar;
}

List<A> listA = List.of(...);
List<A> listB = List.of(...);

I tried

return listA.stream().anyMatch( a -> listB.stream().anyMatch(b -> {
    a.getType().equals(b.getType());
    a.getValue().equals(b.getValue());}
));

...but this doesn't work.

It would be sufficient to find any/the first match and return true then or false if no match can be found.

CodePudding user response：

If you want both properties to match, it should be:

return listA.stream()
            .anyMatch( a -> listB.stream()
                                 .anyMatch(b -> a.getType().equals(b.getType()) &&
                                                a.getValue().equals(b.getValue())));

This will compare all pairs of elements of the two lists until a match is found.