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Consistent nullability in DataAccessUtils through nullableSingleResult

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Issue: SPR-16225
This commit is contained in:
Juergen Hoeller
2017-11-26 17:16:39 +01:00
parent a8323f6a27
commit b1c657fa4b
6 changed files with 72 additions and 35 deletions
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69
spring-tx/src/main/java/org/springframework/dao/support/DataAccessUtils.java
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@@ -47,12 +47,11 @@ public abstract class DataAccessUtils {
*/
@Nullable
public static <T> T singleResult(@Nullable Collection<T> results) throws IncorrectResultSizeDataAccessException {
int size = (results != null ? results.size() : 0);
if (size == 0) {
if (CollectionUtils.isEmpty(results)) {
return null;
}
if (results.size() > 1) {
throw new IncorrectResultSizeDataAccessException(1, size);
throw new IncorrectResultSizeDataAccessException(1, results.size());
}
return results.iterator().next();
}
@@ -60,21 +59,45 @@ public abstract class DataAccessUtils {
/**
* Return a single result object from the given Collection.
* <p>Throws an exception if 0 or more than 1 element found.
* @param results the result Collection (can be {@code null})
* @param results the result Collection (can be {@code null}
* but is not expected to contain {@code null} elements)
* @return the single result object
* @throws IncorrectResultSizeDataAccessException if more than one
* element has been found in the given Collection
* @throws EmptyResultDataAccessException if no element at all
* has been found in the given Collection
*/
@Nullable
public static <T> T requiredSingleResult(@Nullable Collection<T> results) throws IncorrectResultSizeDataAccessException {
int size = (results != null ? results.size() : 0);
if (size == 0) {
if (CollectionUtils.isEmpty(results)) {
throw new EmptyResultDataAccessException(1);
}
if (results.size() > 1) {
throw new IncorrectResultSizeDataAccessException(1, size);
throw new IncorrectResultSizeDataAccessException(1, results.size());
}
return results.iterator().next();
}
/**
* Return a single result object from the given Collection.
* <p>Throws an exception if 0 or more than 1 element found.
* @param results the result Collection (can be {@code null}
* and is also expected to contain {@code null} elements)
* @return the single result object
* @throws IncorrectResultSizeDataAccessException if more than one
* element has been found in the given Collection
* @throws EmptyResultDataAccessException if no element at all
* has been found in the given Collection
* @since 5.0.2
*/
@Nullable
public static <T> T nullableSingleResult(@Nullable Collection<T> results) throws IncorrectResultSizeDataAccessException {
// This is identical to the requiredSingleResult implementation but differs in the
// semantics of the incoming Collection (which we currently can't formally express)
if (CollectionUtils.isEmpty(results)) {
throw new EmptyResultDataAccessException(1);
}
if (results.size() > 1) {
throw new IncorrectResultSizeDataAccessException(1, results.size());
}
return results.iterator().next();
}
@@ -91,12 +114,11 @@ public abstract class DataAccessUtils {
*/
@Nullable
public static <T> T uniqueResult(@Nullable Collection<T> results) throws IncorrectResultSizeDataAccessException {
int size = (results != null ? results.size() : 0);
if (size == 0) {
if (CollectionUtils.isEmpty(results)) {
return null;
}
if (!CollectionUtils.hasUniqueObject(results)) {
throw new IncorrectResultSizeDataAccessException(1, size);
throw new IncorrectResultSizeDataAccessException(1, results.size());
}
return results.iterator().next();
}
@@ -104,7 +126,8 @@ public abstract class DataAccessUtils {
/**
* Return a unique result object from the given Collection.
* <p>Throws an exception if 0 or more than 1 instance found.
* @param results the result Collection (can be {@code null})
* @param results the result Collection (can be {@code null}
* but is not expected to contain {@code null} elements)
* @return the unique result object
* @throws IncorrectResultSizeDataAccessException if more than one
* result object has been found in the given Collection
@@ -113,12 +136,11 @@ public abstract class DataAccessUtils {
* @see org.springframework.util.CollectionUtils#hasUniqueObject
*/
public static <T> T requiredUniqueResult(@Nullable Collection<T> results) throws IncorrectResultSizeDataAccessException {
int size = (results != null ? results.size() : 0);
if (size == 0) {
if (CollectionUtils.isEmpty(results)) {
throw new EmptyResultDataAccessException(1);
}
if (!CollectionUtils.hasUniqueObject(results)) {
throw new IncorrectResultSizeDataAccessException(1, size);
throw new IncorrectResultSizeDataAccessException(1, results.size());
}
return results.iterator().next();
}
@@ -128,7 +150,8 @@ public abstract class DataAccessUtils {
* Throws an exception if 0 or more than 1 result objects found,
* of if the unique result object is not convertible to the
* specified required type.
* @param results the result Collection (can be {@code null})
* @param results the result Collection (can be {@code null}
* but is not expected to contain {@code null} elements)
* @return the unique result object
* @throws IncorrectResultSizeDataAccessException if more than one
* result object has been found in the given Collection
@@ -167,7 +190,8 @@ public abstract class DataAccessUtils {
* 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 convertible to an int.
* @param results the result Collection (can be {@code null})
* @param results the result Collection (can be {@code null}
* but is not expected to contain {@code null} elements)
* @return the unique int result
* @throws IncorrectResultSizeDataAccessException if more than one
* result object has been found in the given Collection
@@ -186,7 +210,8 @@ public abstract class DataAccessUtils {
* 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 convertible to a long.
* @param results the result Collection (can be {@code null})
* @param results the result Collection (can be {@code null}
* but is not expected to contain {@code null} elements)
* @return the unique long result
* @throws IncorrectResultSizeDataAccessException if more than one
* result object has been found in the given Collection
@@ -204,11 +229,11 @@ public abstract class DataAccessUtils {
/**
* Return a translated exception if this is appropriate,
* otherwise return the input exception.
* @param rawException exception we may wish to translate
* otherwise return the given exception as-is.
* @param rawException an exception that we may wish to translate
* @param pet PersistenceExceptionTranslator to use to perform the translation
* @return a translated exception if translation is possible, or
* the raw exception if it is not
* @return a translated persistence exception if translation is possible,
* or the raw exception if it is not
*/
public static RuntimeException translateIfNecessary(
RuntimeException rawException, PersistenceExceptionTranslator pet) {