用代码实现两个超大数相加，要求函数或方法输入两个任意长度（长度可能超过所有基础类型表示的范围）的数值，能计算并输出结果

@Test
	public void testBig() {
		System.out.println(bigAdd("123456789", "9999999999999999999999999"));
	}
 
	public static String bigAdd(String a, String b) {
		char[] charsA = new StringBuilder(a).reverse().toString().toCharArray();
		char[] charsB = new StringBuilder(b).reverse().toString().toCharArray();
 
		int maxLength = Math.max(charsA.length, charsB.length);
 
		int[] result = new int[maxLength + 1];
 
		int temp = 0;
		for (int i = 0; i <= maxLength; i++) {
			temp = result[i];
 
			if (i < charsA.length) {
				temp += charsA[i] - '0';
			}
 
			if (i < charsB.length) {
				temp += charsB[i] - '0';
			}
 
			if (temp >= 10) {
				temp -= 10;
				result[i + 1] = 1;
			}
 
			result[i] = temp;
 
		}
 
		StringBuilder sb = new StringBuilder();
		boolean flag = true;
 
		for (int i = maxLength; i >= 0; i--) {
			if (result[i] == 0 && flag) {
				continue;
			}
 
			flag = false;
			sb.append(result[i]);
		}
 
		return sb.toString();
 
	}