MapAndreas for Shoebill

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;

public class MapAndreas
{
    private MappedByteBuffer mappedByteBuffer;


    public MapAndreas(File mapAndreadData) throws IOException
    {
        FileInputStream in = new FileInputStream(mapAndreadData);
        FileChannel fileChannel = in.getChannel();

        mappedByteBuffer = fileChannel.map(FileChannel.MapMode.READ_ONLY, 0, fileChannel.size());
        fileChannel.close();
        in.close();
    }

    public void close()
    {
        if (mappedByteBuffer == null) return;
        synchronized (mappedByteBuffer)
        {
            mappedByteBuffer = null;
        }
    }

    public float findZ(float x, float y)
    {
        if (mappedByteBuffer == null) return 0.0f;
        if (x < -3000.0f || x > 3000.0f || y > 3000.0f || y < -3000.0f) return 0.0f;

        synchronized (mappedByteBuffer)
        {
            int gridX = ((int) x) + 3000;
            int gridY = (((int) y) - 3000) * -1;
            int dataPos = (gridY * 6000) + gridX;

            mappedByteBuffer.position(dataPos);

            int ch1 = Byte.toUnsignedInt(mappedByteBuffer.get()), ch2 = Byte.toUnsignedInt(mappedByteBuffer.get());
            return ((float) ((ch2 << 8) + (ch1))) / 100.0f;
        }

    }
}