hdf5/HDF5Examples/JAVA/H5G/H5Ex_G_Iterate.java

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 * Copyright by The HDF Group.                                               *
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 * help@hdfgroup.org.                                                        *
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/************************************************************
  This example shows how to iterate over group members using
  H5Gget_obj_info_all.
 ************************************************************/

import static org.hdfgroup.javahdf5.hdf5_h.*;

import java.lang.foreign.Arena;
import java.lang.foreign.MemorySegment;
import java.lang.foreign.ValueLayout;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.Map;

import hdf.hdf5lib.H5;
import hdf.hdf5lib.structs.H5O_token_t;

public class H5Ex_G_Iterate {
    private static String FILENAME    = "groups/h5ex_g_iterate.h5";
    private static String DATASETNAME = "/";

    enum H5O_type {
        H5O_TYPE_UNKNOWN(-1),       // Unknown object type
        H5O_TYPE_GROUP(0),          // Object is a group
        H5O_TYPE_DATASET(1),        // Object is a dataset
        H5O_TYPE_NAMED_DATATYPE(2), // Object is a named data type
        H5O_TYPE_NTYPES(3);         // Number of different object types
        private static final Map<Integer, H5O_type> lookup = new HashMap<Integer, H5O_type>();

        static
        {
            for (H5O_type s : EnumSet.allOf(H5O_type.class))
                lookup.put(s.getCode(), s);
        }

        private int code;

        H5O_type(int layout_type) { this.code = layout_type; }

        public int getCode() { return this.code; }

        public static H5O_type get(int code) { return lookup.get(code); }
    }

    private static void do_iterate(Arena arena)
    {
        long file_id = H5I_INVALID_HID();

        // Open a file using default properties.
        try {
            file_id = H5Fopen(arena.allocateFrom(FILENAME), H5F_ACC_RDONLY(), H5P_DEFAULT());
        }
        catch (Exception e) {
            e.printStackTrace();
        }

        // Begin iteration.
        System.out.println("Objects in root group:");
        try {
            if (file_id >= 0) {
                int count             = (int)H5.H5Gn_members(file_id, DATASETNAME);
                String[] oname        = new String[count];
                int[] otype           = new int[count];
                int[] ltype           = new int[count];
                H5O_token_t[] otokens = new H5O_token_t[count];
                H5.H5Gget_obj_info_all(file_id, DATASETNAME, oname, otype, ltype, otokens, H5_INDEX_NAME());

                // Get type of the object and display its name and type.
                for (int indx = 0; indx < otype.length; indx++) {
                    switch (H5O_type.get(otype[indx])) {
                    case H5O_TYPE_GROUP:
                        System.out.println("  Group: " + oname[indx]);
                        break;
                    case H5O_TYPE_DATASET:
                        System.out.println("  Dataset: " + oname[indx]);
                        break;
                    case H5O_TYPE_NAMED_DATATYPE:
                        System.out.println("  Datatype: " + oname[indx]);
                        break;
                    default:
                        System.out.println("  Unknown: " + oname[indx]);
                    }
                }
            }
        }
        catch (Exception e) {
            e.printStackTrace();
        }

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

    public static void main(String[] args)
    {
        try (Arena arena = Arena.ofConfined()) {
            H5Ex_G_Iterate.do_iterate(arena);
        }
    }
}