hive自定义函数 求和

oracle中有个业务是 各项指标相加求和的，迁移到hive上，自定义函数写法如下：

public class SumTest  extends UDF{ 

	 String retVal = "";
	 double sumpart = 0;
	 public Text evaluate(String... args) {
		String part = "";
		
		int len = args.length;
		for(int i=0; i<len; i++){
			part = args[i];
			if(part == null || "".equals(part.trim())){
				part = "0";
			}
			double partDouble = Double.parseDouble(part);
			sumpart += partDouble;
		}
		retVal = sumpart+""; 
	   return new Text(retVal);	
	 }
	 
}