Find the Biggest number in HashSet/HashMap java

Question

I would like to find the biggest number in HashSet and HashMap. Say I have the number [22,6763,32,42,33] in my HashSet and I want to find the largest number in my current Ha

Answer 1

Note : If you want to find the biggest value from Map try maxEntry.get().getValue() instead of maxEntry.get().getKey()

1. Using Stream

public > V maxUsingStreamAndLambda(Map map) {
    Optional> maxEntry = map.entrySet()
        .stream()
        .max((Entry e1, Entry e2) -> e1.getValue()
            .compareTo(e2.getValue())
        );

    return maxEntry.get().getKey();
}

2. Using Collections.max() with a Lambda Expression

public > V maxUsingCollectionsMaxAndLambda(Map map) {
    Entry maxEntry = Collections.max(map.entrySet(), (Entry e1, Entry e2) -> e1.getValue()
        .compareTo(e2.getValue()));
    return maxEntry.getKey();
}

3. Using Stream with Method Reference

public > V maxUsingStreamAndMethodReference(Map map) {
    Optional> maxEntry = map.entrySet()
        .stream()
        .max(Comparator.comparing(Map.Entry::getValue));
    return maxEntry.get()
        .getKey();
}

4. Using Collections.max()

public > V maxUsingCollectionsMax(Map map) {
    Entry maxEntry = Collections.max(map.entrySet(), new Comparator>() {
        public int compare(Entry e1, Entry e2) {
            return e1.getValue()
                .compareTo(e2.getValue());
        }
    });
    return maxEntry.getKey();
}

5. Using Simple Iteration

public > V maxUsingIteration(Map map) {
    Map.Entry maxEntry = null;
    for (Map.Entry entry : map.entrySet()) {
        if (maxEntry == null || entry.getValue()
            .compareTo(maxEntry.getValue()) > 0) {
            maxEntry = entry;
        }
    }
    return maxEntry.getKey();
}