MapSerializer.java

import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Map;

public class MapSerializer {

    private MapSerializer() {}

    @NonNull
    public static <T extends Map & Serializable> Intent putMapExtra(
            @NonNull Intent intent, @NonNull String name, @NonNull T map)
            throws IOException {
        return intent.putExtra(name, serializeMap(map));
    }

    @Nullable
    public static <T extends Map & Serializable> T getMapExtra(
            @NonNull Intent intent, @NonNull String name)
            throws IOException, ClassNotFoundException, ClassCastException {
        final byte[] serializedMap = intent.getByteArrayExtra(name);
        //noinspection unchecked
        return serializedMap == null ? null : deserializeMap(serializedMap);
    }

    @NonNull
    public static <T extends Map & Serializable> byte[] serializeMap(@NonNull T map)
            throws IOException {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        ObjectOutput out = null;
        try {
            out = new ObjectOutputStream(bos);
            out.writeObject(map);
            return bos.toByteArray();
        }
        finally {
            try {
                if (out != null) {
                    out.close();
                }
            }
            catch (IOException ignore) {}
            try {
                bos.close();
            }
            catch (IOException ignore) {}
        }
    }

    @NonNull
    public static <T extends Map & Serializable> T deserializeMap(@NonNull byte[] serializedMap)
            throws IOException, ClassNotFoundException, ClassCastException {
        ByteArrayInputStream bis = new ByteArrayInputStream(serializedMap);
        ObjectInput in = null;
        try {
            in = new ObjectInputStream(bis);
            //noinspection unchecked
            return (T)in.readObject();
        } finally {
            try {
                bis.close();
            }
            catch (IOException ignore) {}
            try {
                if (in != null) {
                    in.close();
                }
            }
            catch (IOException ignore) {}
        }
    }

}