ArrayUtils.java

/** Runes of Wizardry Mod for Minecraft
 *  Licensed under the GNU GPL version 3
 *  
 *  this file was created by Xilef11 on 2015-12-14
 */
package com.zpig333.runesofwizardry.util;

import java.lang.reflect.Array;
import java.util.Arrays;

/** This class holds utilities for manipulating arrays.
 * @author Xilef11
 *
 */
public class ArrayUtils {
	private ArrayUtils(){}
	/**
	 *  Rotates a 2D array Clockwise by 90�. Assumes that the array is rectangular (i.e all rows have the same number of columns)
	 * @param <T>
	 * @param mat the array to rotate
	 * @return {@code mat} rotated 90� clockwise
	 */
	public static <T> T[][] rotateCW(T[][] mat){
		final int M = mat.length;
		final int N = mat[0].length;
		Class<?> clazz=null;
		//find the first non null item in mat
		for(T[] row:mat){
			for(T col:row){
				if(col!=null){
					clazz=col.getClass();
					break;
				}
			}
			if(clazz!=null)break;
		}
		if(clazz==null)return mat;//all items are null, so rotating changes nothing
		@SuppressWarnings("unchecked")
		T[][] ret = (T[][])Array.newInstance(clazz, new int[]{N,M});
		//System.out.println(mat.getClass()+":::::"+mat[0][0].getClass()+":::::"+ret.getClass());
		for (int r = 0; r < M; r++) {
			for (int c = 0; c < N; c++) {
				ret[c][M-1-r] = mat[r][c];
			}
		}
		return ret;		
	}
	/**
	 * Rotates a 2D array CounterClockwise by 90�. Assumes that the array is rectangular (i.e all rows have the same number of columns)
	 * @param mat the array to rotate
	 * @return {@code mat} rotated 90� counterclockwise
	 */
	public static <T> T[][] rotateCCW(T[][] mat) {
		final int M = mat.length;
		final int N = mat[0].length;
		Class<?> clazz=null;
		//find the first non null item in mat
		for(T[] row:mat){
			for(T col:row){
				if(col!=null){
					clazz=col.getClass();
					break;
				}
			}
			if(clazz!=null)break;
		}
		if(clazz==null)return mat;//all items are null, so rotating changes nothing
		@SuppressWarnings("unchecked")
		T[][] ret = (T[][])Array.newInstance(clazz, new int[]{N,M});
		for (int r = 0; r < N; r++) {
			for (int c = 0; c < M; c++) {
				//ret[c][M-1-r] = mat[r][c];
				ret[r][c] = mat[c][N-1-r];
			}
		}
		return ret;		
	}

	public static <T> T[][] rotate180(T[][] mat) {
		final int M = mat.length;
		final int N = mat[0].length;
		Class<?> clazz=null;
		//find the first non null item in mat
		for(T[] row:mat){
			for(T col:row){
				if(col!=null){
					clazz=col.getClass();
					break;
				}
			}
			if(clazz!=null)break;
		}
		if(clazz==null)return mat;//all items are null, so rotating changes nothing
		@SuppressWarnings("unchecked")
		T[][] ret = (T[][])Array.newInstance(clazz, new int[]{M,N});
		for(int r=0;r<M;r++){
			for(int c=0;c<N;c++){
				ret[r][c] = mat[M-1-r][N-1-c];
			}
		}
		return ret;
	}

	public static String printMatrix(Object[][] mat) {
		StringBuilder sb = new StringBuilder("Matrix = \n");
		System.out.println();
		for (Object[] row : mat) {
			sb.append(Arrays.toString(row));
			sb.append("\n");
		}
		return sb.toString();
	}

}