split array of long values into list of long[] - Java Collection Framework

Java examples for Collection Framework:Array Element

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Description

split array of long values into list of long[]

Demo Code


import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Random;

public class Main{
    public static void main(String[] argv){
        long[] offsetArray = new long[]{34,35,36,37,37,37,67,68,69};
        int numPerBlock = 42;
        boolean shuffled = true;
        System.out.println(java.util.Arrays.toString(splitLongs(offsetArray,numPerBlock,shuffled)));
    }/*  w  w w  .j  a  v a  2s .c o  m*/
    public static Random random = new Random();
    public static List<long[]> splitLongs(long[] offsetArray,
            int numPerBlock, boolean shuffled) {
        List<long[]> result = new ArrayList<long[]>(offsetArray.length
                / numPerBlock + 1);
        long[] tmp = Arrays.copyOf(offsetArray, offsetArray.length);
        if (shuffled) {
            CollectionUtil.shuffle(tmp, 0, tmp.length);
        }
        int i = 0;
        for (; i < offsetArray.length / numPerBlock; i++) {
            result.add(Arrays.copyOfRange(tmp, i * numPerBlock, (i + 1)
                    * numPerBlock));
        }
        if ((i) * numPerBlock < tmp.length) {
            result.add(Arrays.copyOfRange(tmp, i * numPerBlock, tmp.length));
        }
        return result;
    }
    public static int[] shuffle(int[] array) {

        for (int i = 0; i < array.length; i++) {
            int randomPosition = random.nextInt(array.length);
            int temp = array[i];
            array[i] = array[randomPosition];
            array[randomPosition] = temp;
        }

        return array;
    }
    public static void shuffle(long[] array, int startIndex, int endIndex) {
        assert (endIndex <= array.length && startIndex >= 0 && endIndex > 0);
        for (int i = startIndex; i < endIndex; i++) {
            int randomPosition = random.nextInt(endIndex - startIndex)
                    + startIndex;
            long temp = array[i];
            array[i] = array[randomPosition];
            array[randomPosition] = temp;
        }

    }
}

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