IdentityLinkedMap.java

package com.getbase.android.db.loaders;

import com.google.common.collect.Lists;

import java.util.List;

class IdentityLinkedMap<K, V> {

  private static class Entry<Key, Value> {
    Key key;
    Value value;

    private Entry(Key key, Value value) {
      this.key = key;
      this.value = value;
    }
  }

  private List<Entry<K, V>> entries = Lists.newLinkedList();

  public synchronized V put(K key, V value) {
    final int index = findIndexOf(key);
    if (index == -1) {
      entries.add(new Entry<>(key, value));
      return null;
    } else {
      Entry<K, V> entry = entries.get(index);
      V oldValue = entry.value;
      entry.value = value;
      return oldValue;
    }
  }

  public synchronized V remove(K keyToRemove) {
    final int index = findIndexOf(keyToRemove);
    if (index != -1) {
      return entries.remove(index).value;
    } else {
      return null;
    }
  }

  private int findIndexOf(K keyToFind) {
    int i = 0;
    for (Entry<K, V> entry : entries) {
      if (entry.key == keyToFind) {
        return i;
      }
      i++;
    }
    return -1;
  }

  public synchronized V get(K key) {
    final int indexOf = findIndexOf(key);
    if (indexOf != -1) {
      return entries.get(indexOf).value;
    }
    return null;
  }
}