Data Type and Dynamic Binding in java

Question

I read a matrix from a file and all column have a different data type. I can't find a structure to hold and manipulate my data. Thank's for help.

    // I read a matrix from file and all column have a different type.
    int[]    iT = new int[] {1,3,5};
    long[]   lT = new long[] {123, 456, 789};
    double[] dT = new double[] {1.2d, 3.2d, 5.2d};

    // I like to know if there are a kind of structure to hold and manipulate it.
    Collection<Object[]> collection = new HashSet<Object[]>();

    collection.add(iT);
    collection.add(dT);
    collection.add(lT);     

    for(Object[] obj : collection) {

        String type = obj.getClass().getSimpleName();

        switch (type) {

        case "double[]":
            for(Object element : obj) System.out.println(element);
            break;

        case "int[]":
            for(Object element : obj) System.out.println(element);
            break;

        case "long[]":
            for(Object element : obj) System.out.println(element);
            break;
        }
    }

Of course my code not work ;-) – Pat Keraudren Sep 23 '17 at 17:44 — Pat Keraudren, Sep 23 '17 at 17:44

score 0 · Accepted Answer · answered Sep 23 '17 at 18:09

From my understanding of your task,you want all single values in a single collection, not the arrays (correct me if I'm wrong). You can basically put them in (almost) any collection you like (I have used ArrayList), the problem you have is that the primitive arrays need to be boxed before you can add them to your collection:

public static void main(String[] args) {
    int[] iT = new int[] { 1, 3, 5 };
    long[] lT = new long[] { 123, 456, 789 };
    double[] dT = new double[] { 1.2d, 3.2d, 5.2d };

    Integer[] boxedInts = IntStream.of(iT).boxed().toArray(Integer[]::new);
    Long[] boxedLongs = LongStream.of(lT).boxed().toArray(Long[]::new);
    Double[] boxedDoubles = DoubleStream.of(dT).boxed().toArray(Double[]::new);

    Collection<Object> collection = new ArrayList<>();

    collection.addAll(Arrays.asList(boxedInts));
    collection.addAll(Arrays.asList(boxedLongs));
    collection.addAll(Arrays.asList(boxedDoubles));

    for (Object element : collection) {
        System.out.print(element.toString() + " ");
    }
    //prints 1 3 5 123 456 789 1.2 3.2 5.2 
}

Excellent. Can you then please accept the answer to close the question. — JensS, Sep 23 '17 at 18:22

Data Type and Dynamic Binding in java

1 Answers1