Concat function in UDF

Hello All,

I tried to write UDF as below but got lot of errors.

can you check and let me know.

Thanks

String output = "";

if (KOTABNR = "946"||"924")

{

output = VKORG+VTWEG+KUNNR+DATBI;

result.addValue(output);

}

else if (KOTABNR = "906" ||"917"||"924"||"903")

{

output = VKORG+VTWEG+KUNNR+MATNR+DATBI;

result.addValue(output);

}

else if (KOTABNR = "702")

{

output = MATNR+CMPGN_ID+DATBI;

result.addValue(output);

}

else if (KOTABNR = "928")

{

output = VKORG+VTWEG+KUNNR+DATBI;

result.addValue(output);

}

else if (KOTABNR = "703")

{

output = CMPGN_ID+DATBI;

result.addValue(output);

}

else if (KOTABNR = "946")

{

output = VTWEG+KUNNR+DATBI;

result.addValue(output);

}

else if (KOTABNR = "700")

{

output =VKORG+KUNNR+MATNR+CMPGN_ID+DATBI;

result.addValue(output);

}

else if (KOTABNR = "701")

{

output =VKORG+KUNNR+CMPGN_ID+DATBI;

result.addValue(output);

}

else if (KOTABNR = "928")

{

output =VKORG+VTWEG+KUNNR+DATBI;

result.addValue(output);

}