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Commit d7899c3

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map with timestamp done
1 parent 97addbe commit d7899c3

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2 files changed

+55
-2
lines changed

2 files changed

+55
-2
lines changed

‎src/main/java/com/rampatra/java8/FlatMapInStreams.java

Lines changed: 5 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,10 @@
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public class FlatMapInStreams {
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public static long countTotalIngredientsInAllDishes(List<Dish> dishes) {
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return dishes.stream().map(Dish::getIngredients).flatMap(List::stream).count();
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return dishes.stream()
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.map(Dish::getIngredients)
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.flatMap(List::stream)
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.count();
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}
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public static void main(String[] args) {
@@ -21,7 +24,7 @@ public static void main(String[] args) {
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ingredients.add("haldi");
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List<Dish> dishes = Arrays.asList(
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new Dish("biriyani", 600, ingredients),
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new Dish("biriyani", 600, new ArrayList<>()));
27+
new Dish("pulao", 600, new ArrayList<>()));
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// to show whether empty List is counted in flatMap
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System.out.println(countTotalIngredientsInAllDishes(dishes));
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}
Lines changed: 50 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,50 @@
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package com.rampatra.misc;
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import java.util.Date;
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import java.util.HashMap;
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import java.util.Map;
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/**
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* @author rampatra
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* @since 2019年05月15日
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*/
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public class MapWithTimestamp<K, V> {
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private final Map<K, Map<Long, V>> map = new HashMap<>();
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public V get(K key, Long timestamp) {
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Map<Long, V> entry = map.get(key);
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return entry != null ? entry.get(timestamp) : null;
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}
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public void put(K key, Long timestamp, V value) {
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Map<Long, V> entry = map.get(key);
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if (entry == null) {
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map.put(key, new HashMap<Long, V>() {{
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put(timestamp, value);
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}});
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} else {
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entry.put(timestamp, value);
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}
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}
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public static void main(String[] args) throws Exception {
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MapWithTimestamp<Integer, Integer> mapWithTimestamp = new MapWithTimestamp<>();
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long timestamp1;
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long timestamp2;
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long timestamp3;
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mapWithTimestamp.put(1, timestamp1 = new Date().getTime(), 10_0);
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mapWithTimestamp.put(2, timestamp2 = new Date().getTime(), 20_0);
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Thread.sleep(100);
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mapWithTimestamp.put(2, new Date().getTime(), 20_1);
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Thread.sleep(100);
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mapWithTimestamp.put(2, new Date().getTime(), 20_2);
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mapWithTimestamp.put(3, timestamp3 = new Date().getTime(), 30_0);
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System.out.println(mapWithTimestamp.get(2, timestamp2));
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System.out.println(mapWithTimestamp.get(3, timestamp2));
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System.out.println(mapWithTimestamp.get(3, timestamp3));
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}
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}

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