Java数组小工具

package algorithm.study.utils;

import java.util.Arrays;

/**
 * A tool prepare for Array,it convenient to create a random array for sort and print them
 *
 * @author ygh 2017年2月27日
 */
public class ArraysTools {

    /**
     * Print a int[] into console
     *
     * @param arr The array need to print
     */
    public static void toStringIntArray(int[] arr) {
        System.out.println(Arrays.toString(arr));
    }

    /**
     * Get a random array by size and max value
     *
     * @param size The size the new array you want to create
     * @param maxValue The max value in the array;
     * @return A random array
     */
    public static int[] getRandomArray(int size, int maxValue) {
        int[] arr = new int[size];
        for (int i = 0; i < size; i++) {
            arr[i] = getIntRandomValue(maxValue);
        }
        return arr;
    }

    /**
     * Get a random that less than max value
     *
     * @param maxValue The max value you get the random number
     * @return A random number less than max value
     */
    public static int getIntRandomValue(int maxValue) {
        return (int) (Math.random() * maxValue);
    }

    /**
     * Get a random value in a integer array
     *
     * @param arr A value come from this array
     * @return A random value comes from this array
     */
    public static int getRandomValue(int[] arr) {
        int length = arr.length;
        return (arr[getIntRandomValue(length)]);
    }

    /**
     * Get the max value in a Array.
     *
     * @param arr[] The max value come from
     * @return The max value in this array
     */
    public static int getMaxValue(int arr[]) {
        int max = arr[0];
        for (int i = 1; i < arr.length - 1; i++) {
            if (max < arr[i]) {
                max = arr[i];
            }
        }
        return max;
    }

    /**
     * Get average of an integer array
     *
     * @param arr The array provide data
     * @return The average of this array
     */
    public static double getArrayAverage(int[] arr) {
        int length = arr.length;
        int sum = 0;
        for (int i = 0; i < length; i++) {
            sum += arr[i];
        }
        return (sum / length);
    }

    /**
     * Copy an array to new array
     *
     * @param arr The array needed to copy
     * @return The copied array
     */
    public static int[] copy(int arr[]) {
        int length = arr.length;
        int newArr[] = new int[length];
        for (int i = 0; i < length; i++) {
            newArr[i] = arr[i];
        }
        return newArr;
    }

    /**
     * Reverse the elements within an array
     *
     * @param arr An array want to reverse all elements
     */
    public static void reverse(int[] arr) {
        int tmp;
        int length = arr.length;
        for (int i = 0; i < length / 2; i++) {
            tmp = arr[i];
            arr[i] = arr[length - 1 - i];
            arr[length - 1 - i] = tmp;
        }
    }

    /**
     * multiple two matrix-matrix(square matrices)
     * c[][]=a[][]*b[][]
     * @return The result of two matrix multiple
     */
    public static double[][] multiplation() {
        int length = 5;
        double[][] arr = new double[length][length];
        double[][] multip = new double[length][length];
        for (int i = 0; i < length; i++) {
            for (int j = 0; i < length; i++) {
                for (int k = 0; k < length; k++) {
                    multip[i][i] = arr[i][k] * arr[k][j];
                }
            }
        }
        return multip;
    }

}