65 lines
1.7 KiB
Java
65 lines
1.7 KiB
Java
// equalshashcode/SlowMap.java
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// (c)2020 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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// A Map implemented with ArrayLists
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import java.util.*;
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import onjava.*;
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public class SlowMap<K, V> extends AbstractMap<K, V> {
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private List<K> keys = new ArrayList<>();
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private List<V> values = new ArrayList<>();
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@Override
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public V put(K key, V value) {
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V oldValue = get(key); // The old value or null
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if(!keys.contains(key)) {
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keys.add(key);
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values.add(value);
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} else
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values.set(keys.indexOf(key), value);
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return oldValue;
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}
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@Override
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public V get(Object key) { // key: type Object, not K
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if(!keys.contains(key))
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return null;
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return values.get(keys.indexOf(key));
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}
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@Override
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public Set<Map.Entry<K, V>> entrySet() {
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Set<Map.Entry<K, V>> set= new HashSet<>();
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Iterator<K> ki = keys.iterator();
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Iterator<V> vi = values.iterator();
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while(ki.hasNext())
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set.add(new MapEntry<>(ki.next(), vi.next()));
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return set;
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}
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public static void main(String[] args) {
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SlowMap<String,String> m= new SlowMap<>();
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m.putAll(Countries.capitals(8));
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m.forEach((k, v) ->
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System.out.println(k + "=" + v));
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System.out.println(m.get("BENIN"));
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m.entrySet().forEach(System.out::println);
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}
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}
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/* Output:
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CAMEROON=Yaounde
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ANGOLA=Luanda
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BURKINA FASO=Ouagadougou
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BURUNDI=Bujumbura
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ALGERIA=Algiers
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BENIN=Porto-Novo
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CAPE VERDE=Praia
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BOTSWANA=Gaberone
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Porto-Novo
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CAMEROON=Yaounde
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ANGOLA=Luanda
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BURKINA FASO=Ouagadougou
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BURUNDI=Bujumbura
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ALGERIA=Algiers
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BENIN=Porto-Novo
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CAPE VERDE=Praia
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BOTSWANA=Gaberone
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*/
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