java_upgrade/src/main/java/sorting/SortGolfers.java at master · sairam-github/java_upgrade · GitHub

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package sorting;

import java.util.*;

import java.util.stream.Collectors;

import static java.util.Comparator.comparing;

import static java.util.Comparator.comparingInt;

public class SortGolfers {

private List<Integer> integers = Arrays.asList(3, 1, 4, 1, 5, 9);

public List<Integer> getValuesBefore() {

List<Integer> results = new ArrayList<>();

for (Integer i : integers) {

int val = i * 2;

if (val % 3 == 0) {

results.add(i);

}

return results;

}

public List<Integer> getValuesAfter() {

return integers.stream()

.mapToInt(n -> n * 2)

.filter(n -> n % 3 == 0)

.boxed()

.collect(Collectors.toList());

}

private static List<Golfer> golfers = Arrays.asList(

new Golfer("Jack", "Nicklaus", 68),

new Golfer("Tiger", "Woods", 70),

new Golfer("Tom", "Watson", 70),

new Golfer("Ty", "Webb", 68),

new Golfer("Bubba", "Watson", 70));

public static void printSorted(Comparator<Golfer> comparator) {

System.out.println("----------");

golfers.stream()

.sorted(comparator)

.forEach(System.out::println);

}

public static void main(String[] args) {

Golfer nicklaus = golfers.get(0);

System.out.println(nicklaus);

// sort by score

SortGolfers.printSorted(comparingInt(Golfer::getScore));

// sort by score, descending

SortGolfers.printSorted(comparingInt(Golfer::getScore).reversed());

// sort by score, then last name

SortGolfers.printSorted(comparingInt(Golfer::getScore)

.thenComparing(Golfer::getLast));

// sort by score, then last name, then first name

SortGolfers.printSorted(comparingInt(Golfer::getScore)

.thenComparing(Golfer::getLast)

.thenComparing(Golfer::getFirst));

List<Golfer> sorted = golfers.stream()

.sorted(comparing(Golfer::getScore)

.thenComparing(Golfer::getLast)

.thenComparing(Golfer::getFirst))

.collect(Collectors.toList());

// The sort still maintains references to the same objects

System.out.println(sorted.get(0) == nicklaus);

// Copy, then sort the copies

System.out.println("Sorting the copies:");

sorted = golfers.stream()

.map(Golfer::new) // Make new golfers that are copies of the originals

.sorted(comparing(Golfer::getScore)

.thenComparing(Golfer::getLast)

.thenComparing(Golfer::getFirst))

.collect(Collectors.toList());

System.out.println(sorted.get(0) == nicklaus);

// Partition Golfers into two categories: above and below score = 70

Map<Boolean, List<Golfer>> map = golfers.stream()

.collect(Collectors.partitioningBy(g -> g.getScore() < 70));

System.out.println(map);

System.out.println("Printing the partitioned map:");

map.forEach( (key, golferList) -> {

System.out.println(key);

golferList.forEach(System.out::println);

});

}

java_upgrade/src/main/java/sorting/SortGolfers.java at master · sairam-github/java_upgrade · GitHub

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