checkarray codecheck v1

CheckArray.java

/*
 * CheckArray.java
 *
 * Implements a sorted method and several Boolean methods that determine
 * whether the array fits a pattern.
 *
 * @author EZRA GOLDNER <24goldnere@brooklinek12.org>
 */

public class ArrayCheck
{
    /////////////////////////////// FIELDS ///////////////////////////////

    private int[] array;

    //////////////////////////// CONSTRUCTORS ////////////////////////////

    public ArrayCheck(int[] array) {
        this.array = array;
    }

    ////////////////////////////// METHODS ///////////////////////////////

    /** Return a copy of this.array.
     * @return a copy of array
     */
    public int[] getArrayCopy() {
        int[] result = new int[array.length];
        for (int i = 0; i < array.length; i++)
            result[i] = array[i];
        return result;
    }

    /** Return copy of this.array sorted by increasing value.
     * @return new array with elements of array sorted by increasing value
     * @link https://www.toptal.com/developers/sorting-algorithms/selection-sort
     */
    public int[] sorted() {
        // Copy array to result so result can be returned sorted.
        int[] result = getArrayCopy();
         for (int i = 0; i < array.length - 1; i++) {
            int next_index = i;
            for (int j = i + 1; j < array.length; j++) {
               if (result[j] < result[next_index])
                  next_index = j;
            }
            int old = result[next_index];
            result[next_index] = result[i];
            result[i] = old;
         }
         return result;
    }

    /** Return whether this.array is in increasing numerical order.
     * @return true if this.array is in increasing numerical order, false otherwise
     */
    public boolean isSorted() {
        for (int i = 0; i < array.length - 1; i++) {
           if (array[i] > array[i + 1])
              return false;
        }
        return true;
    }

    /** Return whether array[i] == T(i) for all i on [0, array.length).
     * @return true if array[i] == T(i) for all i on [0, array.length), false otherwise
     */
    public boolean isTriangular() {
        for (int i = 0; i < array.length; i++) {
           int Ti = (int) ((Math.pow(i, 2) + i) / 2);
           if (Ti != array[i])
              return false;
        }
        return true;
    }

    /** Return whether array[i] == i! for all i on [0, array.length).
     * @return true if array[i] == i! for all i on [0, array.length), false otherwise
     */
    public boolean isFactorial() {
        for (int i = 0; i < array.length; i++) {
           int factorial = 1;
           for (int j = i; j > 1; j--) {
              factorial *= j;
           }
           if (factorial != array[i])
              return false;
        }
        return true;
    }

    /** Return whether array is part of a Fibonacci sequence. That is:
     * this.array[n] == this.array[n - 2] + this.array[n - 1] for all n.
     * @return true if this.array is part of a Fibonacci sequence, false otherwise
     * Precondition: this.array.length >= 3
     */
    public boolean isFibonacci() {
        assert this.array.length >= 3:
            String.format("this.array.length (%s) < 3", this.array.length);
        for (int i = 2; i < array.length; i++) {
           if (array[i] != array[i - 2] + array[i - 1])
              return false;
        }
        return true;
    }
}