CODEWITHSUNDEEP
javadatabasearraylist
Adamo
Adamo

Reputation: 596

ArrayList from database with PreparedStatement

I have a method like this:

public List<Employee> getEmployeeListViaSurname(String surname) {

      List<Employee> EmployeeListViaSurname = new ArrayList<Employee>();
      int id = -1;
      String name = "";


      try {
        PreparedStatement pst = null;
        pst = con.prepareStatement("select * from Employee where surname = ?");
        pst.setString(1, surname);
        ResultSet rs = pst.executeQuery();
        while (rs.next()) {
            id = rs.getInt("id");
            name = rs.getString("name");
            //EmployeeListViaSurname.add(id, name); <---- error
        }
    } catch (Exception e) {
        System.err.println(e);
    }



    return EmployeeListViaSurname;
}

Could somebody show me how can I add employee via surname.

In example getEmployeeListViaSurname("George");

Upvotes: 0

Views: 91

Answers (2)

poida
poida

Reputation: 3599

EmployeeListViaSurname is a java list that holds Employee objects as shown in its type declaration and initialization (the name of the type in the < > brackets):

List<Employee> EmployeeListViaSurname = new ArrayList<Employee>();

The java sdk documentation contains the all of the information for the standard java libraries, telling you the classes available, method signatures and how to use them. In this case see the documentation for List.add(E) (Google for java api docs List or java api docs ArrayList).

Notice that it takes a single E object, which should be the same type of object the list is parameterized over, which in your case is Employee. But you are passing it an int and a String, so on trying to compile it will fail, and you will get a syntax error.

To fix this first instantiate a new Employee object using one of its constructors and then pass that to the add method. E.g. something like:

while (rs.next()) {
  id = rs.getInt("id");
  name = rs.getString("name");
  Employee employee = new Employee(id, name, surname);
  EmployeeListViaSurname.add(employee);
}

The precise details for how you create and initialize an Employee object depends on the Employee class definition.

A constructor is a special method without a return type that has the same name as the class and will look something like public Employee() { ... } or public Employee(String id, String name, String surname) { ... }. If it only has a parameterless constructor use it and then set the fields.

If you need more help you'll need to give us the details for the Employee class.

Upvotes: 2

Anders R. Bystrup
Anders R. Bystrup

Reputation: 16060

An ArrayList contains objects - in your case Employee objects, of which you must create one to add to the ArrayList - you can't add the attributes directly:

// provided a fitting Employee constructor exists:
EmployeeListViaSurname.add( new Employee( id, name ) );

Cheers,

Upvotes: 1

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