106 lines
3.0 KiB
Java
106 lines
3.0 KiB
Java
package com.baeldung.map.mergemaps;
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import one.util.streamex.EntryStream;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.stream.Collectors;
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import java.util.stream.Stream;
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public class MergeMaps {
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private static Map<String, Employee> map1 = new HashMap<>();
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private static Map<String, Employee> map2 = new HashMap<>();
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public static void main(String[] args) {
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initialize();
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mergeFunction();
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streamConcat();
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streamOf();
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streamEx();
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streamMerge();
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}
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private static void streamMerge() {
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Map<String, Employee> map3 = map2.entrySet()
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.stream()
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.collect(
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Collectors.toMap(
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Map.Entry::getKey,
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Map.Entry::getValue,
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(v1, v2) -> new Employee(v1.getId(), v2.getName()),
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() -> new HashMap<>(map1)
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)
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);
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System.out.println(map3);
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}
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private static void streamEx() {
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Map<String, Employee> map3 = EntryStream.of(map1)
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.append(EntryStream.of(map2))
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.toMap((e1, e2) -> e1);
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System.out.println(map3);
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}
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private static void streamOf() {
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Map<String, Employee> map3 = Stream.of(map1, map2)
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.flatMap(map -> map.entrySet().stream())
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.collect(
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Collectors.toMap(
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Map.Entry::getKey,
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Map.Entry::getValue,
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(v1, v2) -> new Employee(v1.getId(), v2.getName())
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)
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);
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map3.entrySet().forEach(System.out::println);
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}
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private static void streamConcat() {
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Map<String, Employee> result = Stream.concat(map1.entrySet().stream(), map2.entrySet().stream()).collect(Collectors.toMap(
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Map.Entry::getKey,
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Map.Entry::getValue,
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(value1, value2) -> new Employee(value2.getId(), value1.getName())
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));
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result.entrySet().forEach(System.out::println);
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}
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private static void mergeFunction() {
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Map<String, Employee> map3 = new HashMap<>(map1);
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map2.forEach(
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(key, value) -> map3.merge(key, value, (v1, v2) ->
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new Employee(v1.getId(), v2.getName()))
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);
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map3.entrySet().forEach(System.out::println);
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}
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private static void initialize() {
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Employee employee1 = new Employee(1L, "Henry");
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map1.put(employee1.getName(), employee1);
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Employee employee2 = new Employee(22L, "Annie");
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map1.put(employee2.getName(), employee2);
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Employee employee3 = new Employee(8L, "John");
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map1.put(employee3.getName(), employee3);
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Employee employee4 = new Employee(2L, "George");
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map2.put(employee4.getName(), employee4);
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Employee employee5 = new Employee(3L, "Henry");
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map2.put(employee5.getName(), employee5);
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}
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}
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