com.jcabi.jdbc

Class SingleHandler<T>

java.lang.Object

com.jcabi.jdbc.SingleHandler<T>

All Implemented Interfaces:

JdbcSession.Handler<T>

public final class SingleHandler<T>
extends Object
implements JdbcSession.Handler<T>

Handler that returns first column in the first row.

Use it when you need the first column in the first row:

Long id = new JdbcSession(source)
   .sql("SELECT id FROM user WHERE name = ?")
   .set("Jeff Lebowski")
   .select(new SingleHandler<Long>(Long.class));

Supported types are: String, Long, Boolean, Byte, Date, and Utc.

By default, the handler throws SQLException if no records are found in the ResultSet. You can change this behavior by using a two-arguments constructor (null will be returned if ResultSet is empty):

String name = new JdbcSession(source)
   .sql("SELECT name FROM user WHERE id = ?")
   .set(555)
   .select(new SingleHandler<Long>(Long.class), true);
 if (name == null) {
   // such a record wasn't found in the database
 }

Since:

0.1.8

Version:

$Id$

Author:

Yegor Bugayenko (yegor@tpc2.com)

To do:

#143 This class should be @Immutable, but we can't do it at the moment, because "Class" type is mutable. Let's refactor somehow.

Constructor Summary

Constructors

Constructor and Description
SingleHandler(Class<T> tpe) Public ctor.
SingleHandler(Class<T> tpe, boolean slnt) Public ctor.

Method Summary

Methods

Modifier and Type	Method and Description
T	handle(ResultSet rset) Process the result set and return some value.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SingleHandler

public SingleHandler(Class<T> tpe)

Public ctor.

Parameters:

tpe - The type to convert to

SingleHandler

public SingleHandler(Class<T> tpe,
             boolean slnt)

Public ctor.

Parameters:

tpe - The type to convert to

slnt - Silently return NULL if there is no row

Method Detail

handle

@Loggable(value=2)
public T handle(ResultSet rset)
         throws SQLException

Process the result set and return some value.

Specified by:

handle in interface JdbcSession.Handler<T>

Parameters:

rset - The result set to process

Returns:

The result

Throws:

SQLException - If something goes wrong inside