How does Comparator.comparing work in Java?

Question

Java

Hello everyone, please help me figure out what the next line does?

.sorted(Comparator.comparing(Matcher::getSourceFileName).thenComparingLong(Matcher::getSourceFileLineNumber))

Full code

getAllMatchers()
            .stream()
            .sorted(Comparator.comparing(Matcher::getSourceFileName).thenComparingLong(Matcher::getSourceFileLineNumber))
            .forEach(matcher -> {
                MatcherImpact matcherImpact = new MatcherImpact();
                matcherImpact.name = matcher.getMatcherSourceLocation();
                impactOverview.put(matcher.getMatcherSourceLocation(), matcherImpact);
                impactList.add(matcherImpact);
            });

For reference
getSourceFileName is a string,
getSourceFileLineNumber is an int

Answer 1

The stream will first be sorted alphabetically by the value returned by `getSourceFileName`, and then (i.e. if the values ​​of `sourceFileName` are the same) will be sorted by the value of `getSourceFileLineNumber`.