39 lines
1.1 KiB
Java
39 lines
1.1 KiB
Java
// onjava/FillMap.java
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// (c)2021 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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package onjava;
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import java.util.*;
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import java.util.function.*;
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import java.util.stream.*;
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public class FillMap {
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public static <K, V> Map<K,V>
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basic(Supplier<Pair<K,V>> pairGen, int size) {
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return Stream.generate(pairGen)
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.limit(size)
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.collect(Collectors
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.toMap(Pair::key, Pair::value));
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}
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public static <K, V> Map<K,V>
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basic(Supplier<K> keyGen,
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Supplier<V> valueGen, int size) {
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return Stream.generate(
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() -> Pair.make(keyGen.get(), valueGen.get()))
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.limit(size)
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.collect(Collectors
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.toMap(Pair::key, Pair::value));
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}
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public static <K, V, M extends Map<K,V>>
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M create(Supplier<K> keyGen,
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Supplier<V> valueGen,
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Supplier<M> mapSupplier, int size) {
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return Stream.generate( () ->
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Pair.make(keyGen.get(), valueGen.get()))
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.limit(size)
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.collect(Collectors
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.toMap(Pair::key, Pair::value,
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(k, v) -> k, mapSupplier));
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}
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}
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