负数的补码怎么求的

public static void main(String[] args)
{
int a = 0B0000000000_0000000000_0000000010_01; // 9
int b = 0B1111111111_1111111111_1111111101_11; // -9

String strResult = String.valueOf(a);
System.out.println(strResult);

String strResult2 = String.valueOf(b);
System.out.println(strResult2);

String strResultN = String.valueOf(a + b);
System.out.println(strResultN);
}