change
StringBuilder param = new StringBuilder();
if (a != null) {
for (String str : a) {
param.append("'").append(str).append("', ");
}
}
StringBuilder param1 = new StringBuilder();
if (b != null) {
for (String str : b) {
param1.append("'").append(str).append("', ");
}
}
String prm = param.toString().length() > 2 ? param.toString()
.substring(0, param.toString().length() - 2) : null;
String prm1 = param1.toString().length() > 2 ? param1.toString()
.substring(0, param1.toString().length() - 2) : null;
String query = "select * from products where ";
if (prm != null && prm1 != null) {
query += "Brand in (" + prm + ") or Flavour in (" + prm1 + ")";
} else if (prm != null && prm1 == null) {
query += "Brand in (" + prm + ")";
} else if (prm1 != null && prm == null) {
query += "Flavour in (" + prm1 + ")";
}