OnJava8-Examples/streams/MapCollector.java at master · xinan-w/OnJava8-Examples · GitHub

History

47 lines (44 loc) · 1.18 KB

Raw

// streams/MapCollector.java

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

import java.util.*;

import java.util.stream.*;

class Pair {

public final Character c;

public final Integer i;

Pair(Character c, Integer i) {

this.c = c;

this.i = i;

}

public Character getC() { return c; }

public Integer getI() { return i; }

@Override public String toString() {

return "Pair(" + c + ", " + i + ")";

}

class RandomPair {

Random rand = new Random(47);

// An infinite iterator of random capital letters:

Iterator<Character> capChars = rand.ints(65,91)

.mapToObj(i -> (char)i)

.iterator();

public Stream<Pair> stream() {

return rand.ints(100, 1000).distinct()

.mapToObj(i -> new Pair(capChars.next(), i));

}

public class MapCollector {

public static void main(String[] args) {

Map<Integer, Character> map =

new RandomPair().stream()

.limit(8)

.collect(

Collectors.toMap(Pair::getI, Pair::getC));

System.out.println(map);

}

/* Output:

{688=W, 309=C, 293=B, 761=N, 858=N, 668=G, 622=F,

751=N}

OnJava8-Examples/streams/MapCollector.java at master · xinan-w/OnJava8-Examples · GitHub

Expand file tree

Breadcrumbs

MapCollector.java

Latest commit

History

Breadcrumbs

MapCollector.java

File metadata and controls