InMemorySharedPreferences.java

package com.f2prateek.rx.preferences;

import android.content.SharedPreferences;
import android.support.annotation.Nullable;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;

public class InMemorySharedPreferences implements SharedPreferences {
  private final Map<String, Object> map;
  private final Set<SharedPreferences.OnSharedPreferenceChangeListener> listeners;

  public InMemorySharedPreferences() {
    map = Collections.synchronizedMap(new LinkedHashMap<String, Object>());
    listeners = Collections.synchronizedSet(new LinkedHashSet<OnSharedPreferenceChangeListener>());
  }

  @Override public Map<String, ?> getAll() {
    return map;
  }

  @Nullable @Override public String getString(String key, String defValue) {
    return get(key, defValue);
  }

  @Nullable @Override public Set<String> getStringSet(String key, Set<String> defValues) {
    return get(key, defValues);
  }

  @Override public int getInt(String key, int defValue) {
    return get(key, defValue);
  }

  @Override public long getLong(String key, long defValue) {
    return get(key, defValue);
  }

  @Override public float getFloat(String key, float defValue) {
    return get(key, defValue);
  }

  @Override public boolean getBoolean(String key, boolean defValue) {
    return get(key, defValue);
  }

  private <T> T get(String key, T defValue) {
    if (map.containsKey(key)) {
      try {
        return (T) map.get(key);
      } catch (ClassCastException e) {
        return defValue;
      }
    }
    return defValue;
  }

  @Override public boolean contains(String key) {
    return map.containsKey(key);
  }

  @Override public Editor edit() {
    return new Editor() {
      private final Map<String, Object> edits =
          Collections.synchronizedMap(new LinkedHashMap<String, Object>());
      private boolean clear;

      @Override public Editor putString(String key, String value) {
        edits.put(key, value);
        return this;
      }

      @Override public Editor putStringSet(String key, Set<String> values) {
        edits.put(key, values);
        return this;
      }

      @Override public Editor putInt(String key, int value) {
        edits.put(key, value);
        return this;
      }

      @Override public Editor putLong(String key, long value) {
        edits.put(key, value);
        return this;
      }

      @Override public Editor putFloat(String key, float value) {
        edits.put(key, value);
        return this;
      }

      @Override public Editor putBoolean(String key, boolean value) {
        edits.put(key, value);
        return this;
      }

      @Override public Editor remove(String key) {
        edits.put(key, this);
        return this;
      }

      @Override public Editor clear() {
        clear = true;
        return this;
      }

      @Override public boolean commit() {
        if (clear) {
          for (String key : map.keySet()) {
            map.remove(key);
            for (OnSharedPreferenceChangeListener listener : listeners) {
              listener.onSharedPreferenceChanged(InMemorySharedPreferences.this, key);
            }
          }
          return true;
        }

        for (Map.Entry<String, Object> entry : edits.entrySet()) {
          if (entry.getValue() == this) {
            map.remove(entry.getKey());
          } else {
            map.remove(entry.getKey());
          }

          for (OnSharedPreferenceChangeListener listener : listeners) {
            listener.onSharedPreferenceChanged(InMemorySharedPreferences.this, entry.getKey());
          }
        }

        return true;
      }

      @Override public void apply() {
        commit();
      }
    };
  }

  @Override
  public void registerOnSharedPreferenceChangeListener(OnSharedPreferenceChangeListener listener) {
    listeners.add(listener);
  }

  @Override public void unregisterOnSharedPreferenceChangeListener(
      OnSharedPreferenceChangeListener listener) {
    listeners.remove(listener);
  }
}