SQLite Check if column exist or not

I want to select column at agregasi table, if exist do something, but if columns does not exist show/print message 'Column does not exist'. I could run code below while columns exist:

String keywords1={'pesawat','terbang'}; 
String sql1 = "SELECT " + keywords + " FROM agregasi"; //columns exist at agregasi table
Cursor c1 = myDbHelper.rawQuery(sql1, null);
if (c1.moveToFirst()) {
   // do something
}

When i using code below, what should i do to print error message?

String keywords2={'psawat','terang'}; 
String sql2 = "SELECT " + keywords + " FROM agregasi"; //columns does not exist at table 
Cursor c2 = myDbHelper.rawQuery(sql2, null);
// what should i do get error message and show/print using toast