Testing the algorithm using Linkedhashmap

Question

Good afternoon. I want to test the LRU algorithm.

My implementation of LRU:

public class LRUCache {

    private int capacity;
    private LinkedHashMap<Integer, Element> cacheMap = new LinkedHashMap<Integer, Element>(0, 0.75f, true);

    public LRUCache(int capacity) {
        this.capacity = capacity;
    }

    private Element newEntity = new Element();

    public void put(int key, String value) {
        if (cacheMap.size() == capacity) {
            Map.Entry<Integer, Element> element = cacheMap.entrySet().iterator().next();
            int tempKey = element.getKey();
            cacheMap.remove(tempKey);
            addToMap(key, value);
        } else {
            addToMap(key, value);
        }
    }

    public void addToMap(int key, String value) {
        newEntity.setValue(value);
        cacheMap.put(key, newEntity);
    }

}

Test:

LRUCache actualList = new LRUCache<>(2);
LinkedHashMap<Integer, String> expectedList = new LinkedHashMap<>();

@Test
public void test(){

    actualList.put(1, "a");
    actualList.put(2, "b");
    actualList.put(3, "c");

    expectedList.put(2, "b");
    expectedList.put(3, "c");

    Assert.assertEquals(expectedList, actualList);

}

I've tried converting my actualList to map in LRUCache :

public LinkedHashMap converter() {
    return new LinkedHashMap(cacheMap);
}

But in all my attempts to transform my algorithm, a new Linkedhashmap object is created each time. I thought maybe you need to copy from one map to another, but then it will be larger than the specified size.

Due to the small Luggage of knowledge, I know that make somewhere a stupid mistake, please tell me how to do it properly or point to an example.

Answer 1

Your 'LRUCache' class doesn't implement hashCode or equals so the test line:

Assert.assertEquals(expectedList, actualList); is using the default Object implementation which will be returning false.

Perhaps you mean to make LRUCache a subclass of AbstractMap, or if you don't need that, just have your test compare the internal contents cacheMap with the expected contents.