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## org.springframework.dao.support
Class DataAccessUtils

    java.lang.Object
      org.springframework.dao.support.DataAccessUtils

    public abstract class DataAccessUtils

extends Object

Miscellaneous utility methods for DAO implementations. Useful with any data access technology.

Since:
  1.0.2
Author:
  Juergen Hoeller

Constructor Summary
`DataAccessUtils()`

Method Summary
`static int` | `intResult(Collection results)` Return a unique int result from the given Collection.
`static long` | `longResult(Collection results)` Return a unique long result from the given Collection.
`static
`<T> T`
` | `objectResult(Collection<?> results, Class<T> requiredType)` Return a unique result object from the given Collection.
`static
`<T> T`
` | `requiredSingleResult(Collection<T> results)` Return a single result object from the given Collection.
`static
`<T> T`
` | `requiredUniqueResult(Collection<T> results)` Return a unique result object from the given Collection.
`static
`<T> T`
` | `singleResult(Collection<T> results)` Return a single result object from the given Collection.
`static RuntimeException` | `translateIfNecessary(RuntimeException rawException, PersistenceExceptionTranslator pet)` Return a translated exception if this is appropriate, otherwise return the input exception.
`static
`<T> T`
` | `uniqueResult(Collection<T> results)` Return a unique result object from the given Collection.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### DataAccessUtils

    public DataAccessUtils()

Method Detail

### singleResult

    public static <T> T singleResult(Collection<T> results)
                          throws IncorrectResultSizeDataAccessException

  Return a single result object from the given Collection.

  Returns `null` if 0 result objects found; throws an exception if more than 1 element found.

  Parameters:
    `results` - the result Collection (can be `null`)
  Returns:
    the single result object, or `null` if none
  Throws:
    `IncorrectResultSizeDataAccessException` - if more than one element has been found in the given Collection

### requiredSingleResult

    public static <T> T requiredSingleResult(Collection<T> results)
                                  throws IncorrectResultSizeDataAccessException

  Return a single result object from the given Collection.

  Throws an exception if 0 or more than 1 element found.

  Parameters:
    `results` - the result Collection (can be `null`)
  Returns:
    the single result object
  Throws:
    `IncorrectResultSizeDataAccessException` - if more than one element has been found in the given Collection
    `EmptyResultDataAccessException` - if no element at all has been found in the given Collection

### uniqueResult

    public static <T> T uniqueResult(Collection<T> results)
                          throws IncorrectResultSizeDataAccessException

  Return a unique result object from the given Collection.

  Returns `null` if 0 result objects found; throws an exception if more than 1 instance found.

  Parameters:
    `results` - the result Collection (can be `null`)
  Returns:
    the unique result object, or `null` if none
  Throws:
    `IncorrectResultSizeDataAccessException` - if more than one result object has been found in the given Collection
  See Also:
    `CollectionUtils.hasUniqueObject(java.util.Collection)`

### requiredUniqueResult

    public static <T> T requiredUniqueResult(Collection<T> results)
                                  throws IncorrectResultSizeDataAccessException

  Return a unique result object from the given Collection.

  Throws an exception if 0 or more than 1 instance found.

  Parameters:
    `results` - the result Collection (can be `null`)
  Returns:
    the unique result object
  Throws:
    `IncorrectResultSizeDataAccessException` - if more than one result object has been found in the given Collection
    `EmptyResultDataAccessException` - if no result object at all has been found in the given Collection
  See Also:
    `CollectionUtils.hasUniqueObject(java.util.Collection)`

### objectResult

    public static <T> T objectResult(Collection<?> results,
                                     Class<T> requiredType)
                          throws IncorrectResultSizeDataAccessException,
                                 TypeMismatchDataAccessException

  Return a unique result object from the given Collection. Throws an exception if 0 or more than 1 result objects found, of if the unique result object is not convertable to the specified required type.

  Parameters:
    `results` - the result Collection (can be `null`)
  Returns:
    the unique result object
  Throws:
    `IncorrectResultSizeDataAccessException` - if more than one result object has been found in the given Collection
    `EmptyResultDataAccessException` - if no result object at all has been found in the given Collection
    `TypeMismatchDataAccessException` - if the unique object does not match the specified required type

### intResult

    public static int intResult(Collection results)
                         throws IncorrectResultSizeDataAccessException,
                                TypeMismatchDataAccessException

  Return a unique int result from the given Collection. Throws an exception if 0 or more than 1 result objects found, of if the unique result object is not convertable to an int.

  Parameters:
    `results` - the result Collection (can be `null`)
  Returns:
    the unique int result
  Throws:
    `IncorrectResultSizeDataAccessException` - if more than one result object has been found in the given Collection
    `EmptyResultDataAccessException` - if no result object at all has been found in the given Collection
    `TypeMismatchDataAccessException` - if the unique object in the collection is not convertable to an int

### longResult

    public static long longResult(Collection results)
                           throws IncorrectResultSizeDataAccessException,
                                  TypeMismatchDataAccessException

  Return a unique long result from the given Collection. Throws an exception if 0 or more than 1 result objects found, of if the unique result object is not convertable to a long.

  Parameters:
    `results` - the result Collection (can be `null`)
  Returns:
    the unique long result
  Throws:
    `IncorrectResultSizeDataAccessException` - if more than one result object has been found in the given Collection
    `EmptyResultDataAccessException` - if no result object at all has been found in the given Collection
    `TypeMismatchDataAccessException` - if the unique object in the collection is not convertable to a long

### translateIfNecessary

    public static RuntimeException translateIfNecessary(RuntimeException rawException,
                                                        PersistenceExceptionTranslator pet)

  Return a translated exception if this is appropriate, otherwise return the input exception.

  Parameters:
    `rawException` - exception we may wish to translate
    `pet` - PersistenceExceptionTranslator to use to perform the translation
  Returns:
    a translated exception if translation is possible, or the raw exception if it is not

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