OnJava8-Examples/equalshashcode/SlowMap.java at master · CSapprenticeWT/OnJava8-Examples · GitHub

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// equalshashcode/SlowMap.java

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

// A Map implemented with ArrayLists

import java.util.*;

import onjava.*;

public class SlowMap<K, V> extends AbstractMap<K, V> {

private List<K> keys = new ArrayList<>();

private List<V> values = new ArrayList<>();

@Override public V put(K key, V value) {

V oldValue = get(key); // The old value or null

if(!keys.contains(key)) {

keys.add(key);

values.add(value);

} else

values.set(keys.indexOf(key), value);

return oldValue;

}

@Override

public V get(Object key) { // key: type Object, not K

if(!keys.contains(key))

return null;

return values.get(keys.indexOf(key));

}

@Override public Set<Map.Entry<K, V>> entrySet() {

Set<Map.Entry<K, V>> set= new HashSet<>();

Iterator<K> ki = keys.iterator();

Iterator<V> vi = values.iterator();

while(ki.hasNext())

set.add(new MapEntry<>(ki.next(), vi.next()));

return set;

}

public static void main(String[] args) {

SlowMap<String,String> m= new SlowMap<>();

m.putAll(Countries.capitals(8));

m.forEach((k, v) ->

System.out.println(k + "=" + v));

System.out.println(m.get("BENIN"));

m.entrySet().forEach(System.out::println);

}

/* Output:

CAMEROON=Yaounde

ANGOLA=Luanda

BURKINA FASO=Ouagadougou

BURUNDI=Bujumbura

ALGERIA=Algiers

BENIN=Porto-Novo

CAPE VERDE=Praia

BOTSWANA=Gaberone

Porto-Novo