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POHow can I replace a java mutable class with its immutable couterpart in scala?
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  1. POHow can I replace a java mutable class with its immutable couterpart in scala?
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    copied!<p>I'm trying to understand how to use immutable classes in scala as a replacement for mutable java classes.</p> <p>My example use case is searching for contacts in a database. When programming imperatively you would pull each field from the database table and set it on the java object.</p> <p>How would you do this in Scala using immutable types and functional style?</p> <p>I know I could use a constructor and create a new instance of the object passing all required data to it, but for large complex data structures this doesn't seem elegant. </p> <p>What is the "Scala" / "Functional" way to accomplish this? Or what are some best practices related to constructing complex immutable types?</p> <pre><code>public List&lt;Contact&gt; search(String firstName, String lastName) throws SQLException { List&lt;Contact&gt; contacts = new ArrayList&lt;Contact&gt;(); Connection con = null; PreparedStatement ps = null; ResultSet rs = null; try { con = dataSource.getConnection(); ps = con.prepareStatement("select * from contacts where first_name like ? and last_name like ?"); ps.setString(1, "%" + firstName + "%"); ps.setString(1, "%" + lastName + "%"); rs = ps.executeQuery(); while (rs.next()) { Contact contact = new Contact(); contact.setFirstName(rs.getString("first_name")); contact.setMiddleName(rs.getString("middle_name")); contact.setLastName(rs.getString("last_name")); Date birthday = rs.getDate("birthday"); if (birthday != null) { contact.setBirthday(new Date(birthday.getTime())); } contacts.add(contact); } } catch (Exception e) { e.printStackTrace(); } finally { rs.close(); ps.close(); con.close(); } return contacts; } </code></pre> <p>Contact POJO</p> <pre><code>import java.util.Date; public class Contact { private String firstName; private String middleName; private String lastName; private Date birthday; public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getMiddleName() { return middleName; } public void setMiddleName(String middleName) { this.middleName = middleName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public Date getBirthday() { return birthday; } public void setBirthday(Date birthday) { this.birthday = birthday; } } </code></pre>
 

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