Anagram - Java code - good style - variable name, and OP enum class

Anagram.java

import java.util.Scanner;

/**
 * 
 * 
 */
public class Solution {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int T = scanner.nextInt();
		scanner.nextLine();
		StringBuilder sb = new StringBuilder();
		for (int t = 0; t < T; t++) {
			String next = scanner.nextLine();
			int result = doAnagramOp(next);
			sb.append(result).append("\n");
		}
		System.out.println(sb);
	}

	private static int doAnagramOp(String next) {
		int length = next.length();
		if ((length & 1) == 1) {
			return -1;
		}
		int[] letterCnt = new int[26];
		String strA = next.substring(0, length / 2);
		String strB = next.substring(length / 2, length);
		findLetterCount(strA, letterCnt, OP.PLUS);
		findLetterCount(strB, letterCnt, OP.MINUS);
		boolean noChange = true;
		int twiceChangeSum = 0;
		for (int i = 0; i < 26; i++) {
			if (letterCnt[i] == 0) {
				continue;
			} else {
				noChange = false;
				twiceChangeSum += Math.abs(letterCnt[i]);
			}
		}
		if (noChange) {
			return 0;
		} else {
			return twiceChangeSum / 2;
		}
	}

	private static void findLetterCount(String str, int[] letterCnt, OP op) {
		int len = str.length();
		for (int i = 0; i < len; i++) {
			int idx = str.charAt(i) - 'a';
			switch (op) {
			case PLUS:
				letterCnt[idx]++;
				break;
			case MINUS:
				letterCnt[idx]--;
				break;
			}
		}
	}

	private enum OP {
		PLUS, MINUS;
	}

}