java_upgrade/src/main/java/lambdas/MapDemo.java at master · amhtech/java_upgrade · GitHub

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package lambdas;

import java.util.Comparator;

import java.util.HashMap;

import java.util.Map;

public class MapDemo {

public static void main(String[] args) {

Map<String, Integer> map = new HashMap<>();

map.put("c", 2);

map.put("a", 1);

map.put("d", 3);

map.put("b", 2);

map.computeIfAbsent("e", String::length);

map.computeIfAbsent("b", String::length);

map.computeIfPresent("b", (k, v) -> {

System.out.printf("k = %s,v = %d%n", k, v);

return v * 2;

});

map.forEach((k,v) -> System.out.println(k + " maps to " + v));

map.entrySet().stream()

.sorted(Map.Entry.comparingByKey(Comparator.reverseOrder()))

.forEach(System.out::println);

map.entrySet().stream()

.sorted(Map.Entry.comparingByValue())

.forEach(System.out::println);

}

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