使用JRI在Java中调用R的sqldf包

I have developed java code using JRI for executing the R code on Java. Now, I have come across a problem (picking up distinct values in the column of a data frame) where I have to use sqldf package of R and am trying to use its function in my Java code. Here is the sample code (Orange is the dataset already present in R by default):I have developed java code using JRI for execut