兄弟们，这个怎么转换成Java代码
def Cosine(x,y):
sum_xy = 0.0;
normX = 0.0;
normY = 0.0;
for a,b in zip(x,y):
sum_xy += a*b
normX += a**2
normY += b**2
if normX == 0.0 or normY == 0.0:
return None
else:
return sum_xy / ((normX*normY)**0.5)