ModelManager.java

package etfos.hr.tio;


import android.content.Context;
import android.util.Log;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.reflect.TypeToken;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class ModelManager<T extends Serializable> implements Manager {
    public static final String TAG = ModelManager.class.getSimpleName();


    private final File mFile;
    private Context mContext;

    private List<T> mItems;

    protected final String FILE_NAME = new TypeToken<T>() {}.getType().getClass().getName();
    private static ModelManager sInstance;


    public static ModelManager getInstance(Context context) {
        if (sInstance == null) {
            sInstance =  new ModelManager(context);
        }
        return sInstance;
    }

    private ModelManager(Context context) {
        mContext = context;
        mFile = new File(mContext.getFilesDir(), FILE_NAME);
        deserialize();
    }


    @Override
    public void deserialize() {
        try {
            Gson gson = new Gson();
            InputStream is = mContext.getAssets().open(FILE_NAME);
            Reader reader = new InputStreamReader(is);
            T[] items =  gson.fromJson(reader, new TypeToken<T[]>() {}.getType());

            mItems = Arrays.asList(items);
        } catch (Exception e) {
            Log.e(TAG, e.getStackTrace().toString());
        }
    }


    @Override
    public void serialize(ArrayList items) {
        Gson gson = new Gson();

        if (mFile != null) {
            try {
                FileWriter writer = new FileWriter(mFile);
                writer.write(gson.toJson(items));
                writer.flush();
                writer.close();
            } catch (IOException e) {
                Log.e(TAG, e.getStackTrace().toString());
            }
        }

    }
}