Поиск числа в массиве без пары. Генерация файла в YAML формате

Xor.java

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import org.ho.yaml.YamlEncoder;

public class Xor {
	public static void main(String[] args) throws IOException {
		/* Create array */
		int[] arr = { 1, 4, 9, 8, 5, 4, 1, 8, 5 };
		/* Create an object File and passed to the constructor path */
		File file = new File("E:/file.txt");
		/* Checking the existence of the file with the same name */
		if (!file.exists()) {
			file.createNewFile();
		}

		/* Record array to a file */
		OutputStream outStream = new FileOutputStream(file);
		YamlEncoder yamlEncoder = new YamlEncoder(outStream);
		yamlEncoder.writeObject(arr);
		yamlEncoder.close();
		outStream.close();

		/*
		 * Use the properties of XOR: the use of two the same numbers gives zero
		 */
		int notRepeatingElement = arr[0];
		for (int i = 1; i < arr.length; i++) {
			notRepeatingElement ^= arr[i];
		}
		System.out.println(notRepeatingElement);
	}
}