In UDF,want to add text

Hi Experts,

I don't know how to write UDF.The following code is already written and i want to add some text to this UDF,so can you guys plz help me out.

public void concatContent(String[] str, ResultList result, Container container) throws StreamTransformationException{

String resultString="";

for(int i=0;i<str.length;i++)

resultString+=str[i]+"\n";

result.addValue(resultString);

thanks & regards