// 
//   Writing and reading an existing dataset.

package examples.intro;

import ncsa.hdf.hdf5lib.H5;
import ncsa.hdf.hdf5lib.HDF5Constants;

public class H5_ReadWrite {
	private static String FILENAME = "H5_ReadWrite.h5";
	private static String DATASETNAME = "dset";
	private static final int DIM_X = 4;
	private static final int DIM_Y = 6;

	private static void ReadWriteDataset() {
		int file_id = -1;
        int dataspace_id = -1;
		int dataset_id = -1;
        long[] dims = { DIM_X, DIM_Y };
		int[][] dset_data = new int[DIM_X][DIM_Y];

		// Initialize the dataset.
		for (int indx = 0; indx < DIM_X; indx++)
			for (int jndx = 0; jndx < DIM_Y; jndx++)
				dset_data[indx][jndx] = indx * 6 + jndx + 1;

        // Create a new file using default properties.
        try {
            file_id = H5.H5Fcreate(FILENAME, HDF5Constants.H5F_ACC_TRUNC,
                    HDF5Constants.H5P_DEFAULT, HDF5Constants.H5P_DEFAULT);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Create the data space for the dataset.
        try {
            dataspace_id = H5.H5Screate_simple(2, dims, null);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Create the dataset.
        try {
            if ((file_id >= 0) && (dataspace_id >= 0))
                dataset_id = H5.H5Dcreate(file_id, "/" + DATASETNAME,
                        HDF5Constants.H5T_STD_I32BE, dataspace_id,
                        HDF5Constants.H5P_DEFAULT, HDF5Constants.H5P_DEFAULT, HDF5Constants.H5P_DEFAULT);
        }
        catch (Exception e) {
            e.printStackTrace();
        }

		// Write the dataset.
		try {
			if (dataset_id >= 0)
				H5.H5Dwrite(dataset_id, HDF5Constants.H5T_NATIVE_INT,
						HDF5Constants.H5S_ALL, HDF5Constants.H5S_ALL,
						HDF5Constants.H5P_DEFAULT, dset_data);
		}
		catch (Exception e) {
			e.printStackTrace();
		}

		try {
			if (dataset_id >= 0)
				H5.H5Dread(dataset_id, HDF5Constants.H5T_NATIVE_INT,
						HDF5Constants.H5S_ALL, HDF5Constants.H5S_ALL,
						HDF5Constants.H5P_DEFAULT, dset_data);
		}
		catch (Exception e) {
			e.printStackTrace();
		}

		// Close the dataset.
		try {
			if (dataset_id >= 0)
				H5.H5Dclose(dataset_id);
		}
		catch (Exception e) {
			e.printStackTrace();
		}

		// Close the file.
		try {
			if (file_id >= 0)
				H5.H5Fclose(file_id);
		}
		catch (Exception e) {
			e.printStackTrace();
		}
	}

	public static void main(String[] args) {
		H5_ReadWrite.ReadWriteDataset();
	}

}