Editing java Snippet node to check if column exist or create it

Hi all, I have a java Snippet node set as below:

if (c_Column3_Arr1==-10){
out_New_CLASS =  "Not_subs";
} else {
out_New_CLASS = c_Column3;
}

I’d like to add a check before the cmd searching if “Column3Arr1” exist. If exist the node should be follow the setting already present otherwise have to create the column “Column3Arr1” filled by all -10 values and then follow the cmd outNewCLASS = “Not_subs”.

Could someone suggest the right correction to the script?