PageSorter.java

package com.Blackveiled.Diablic.Commands.Utils;

/**
 * Class: PageSorter
 * Author: Blackveiled (Adam Canfield)
 */

public class PageSorter {

    /**
     * The page sorter is a useful tool for sorting objects into collectible arrays, to be used to display pages, and values for those fields.
     *
     */

    Object[] values;
    int pageNum;
    int objectsPerPage;
    int totalPages;

    /**
     * Creates a page sorter for an array of objects (can be a list of Warps, Players, or anything else), and sorts them into pages.
     *
     * These pages can be returned individually, the array length of the objects returned are equal to the Objects Per Page declared
     * in the constructor of the PageSorter.  This objects can be casted back into their original class.  Please note; the PageSorter
     * should not be used for instances of multiple classes, only a single class type.
     * @param values
     * @param pageNumber
     * @param objectsPerPage
     */
    public PageSorter(Object[] values, int pageNumber, int objectsPerPage)    {
        if(values != null) this.values = values; else return; //
        // Ensure values are greater than 0, otherwise the class will break.
        if(pageNumber <= 0) this.pageNum = 1;
        if(objectsPerPage <= 0) this.objectsPerPage = 1;

        // Calculates the last page.  This will be automatically rounded up to the next page number to prevent objects being lost from pages.
        double mp2 = (values.length / objectsPerPage) + .5;
        this.totalPages = (int) Math.round(mp2);
    }

    /**
     * This function will sort the objects and return an array of objects for the provided page.  These objects must be converted back into
     * their original forms to be utilized.
     * @return Object[] (An array of any object)
     */
    public Object[] getObjectsForPage() {
        int pageCount = (pageNum * objectsPerPage) - objectsPerPage;
        int pageFinal = pageCount + objectsPerPage;
        if(pageFinal > values.length)  pageFinal = values.length;

        Object[] output = new Object[objectsPerPage];

        for(int p = pageCount; p < pageFinal; p++)  {
            output[p] = values[p];
        }
        if(output == null) { throw new NullPointerException("PageSorter objects returned are null!"); }
        return output;
    }

    /**
     * Get the index for the last page in this page sorter.
     * @return (int) Value of the last page index.
     */
    public int getTotalPages()    {
        return this.totalPages;
    }

    public int getPage()    {
        return this.pageNum;
    }

    public int getObjectsPerPage()  {
        return this.objectsPerPage;
    }
}