31 lines
1.2 KiB
Java
31 lines
1.2 KiB
Java
package com.baeldung.convertToMap;
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import java.util.*;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.function.Function;
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import java.util.stream.Collectors;
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public class ConvertToMap {
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public Map<String, String> listToMap(List<Book> books) {
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return books.stream().collect(Collectors.toMap(Book::getIsbn, Book::getName));
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}
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public Map<Integer, Book> listToMapWithDupKeyError(List<Book> books) {
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return books.stream().collect(Collectors.toMap(Book::getReleaseYear, Function.identity()));
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}
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public Map<Integer, Book> listToMapWithDupKey(List<Book> books) {
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return books.stream().collect(Collectors.toMap(Book::getReleaseYear, Function.identity(), (existing, replacement) -> existing));
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}
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public Map<Integer, Book> listToConcurrentMap(List<Book> books) {
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return books.stream().collect(Collectors.toMap(Book::getReleaseYear, Function.identity(), (o1, o2) -> o1, ConcurrentHashMap::new));
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}
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public TreeMap<String, Book> listToSortedMap(List<Book> books) {
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return books.stream()
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.collect(Collectors.toMap(Book::getName, Function.identity(), (o1, o2) -> o1, TreeMap::new));
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}
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}
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