Package org.springframework.util

Class ObjectUtils

java.lang.Object

org.springframework.util.ObjectUtils

public abstract class ObjectUtils
extends Object

Miscellaneous object utility methods.

Mainly for internal use within the framework.

Thanks to Alex Ruiz for contributing several enhancements to this class!

Since:

19.03.2004

Author:

Juergen Hoeller, Keith Donald, Rod Johnson, Rob Harrop, Chris Beams, Sam Brannen

See Also:

• ClassUtils
• CollectionUtils
• StringUtils

Constructor Summary

Constructors

Constructor	Description
ObjectUtils()

Method Summary

Modifier and Type	Method	Description
static <A, O extends A> A[]	addObjectToArray(A[] array, O obj)	Append the given object to the given array, returning a new array consisting of the input array contents plus the given object.
static <E extends Enum<?>> E	caseInsensitiveValueOf(E[] enumValues, String constant)	Case insensitive alternative to Enum.valueOf(Class, String).
static boolean	containsConstant(Enum<?>[] enumValues, String constant)	Check whether the given array of enum constants contains a constant with the given name, ignoring case when determining a match.
static boolean	containsConstant(Enum<?>[] enumValues, String constant, boolean caseSensitive)	Check whether the given array of enum constants contains a constant with the given name.
static boolean	containsElement(Object[] array, Object element)	Check whether the given array contains the given element.
static String	getDisplayString(Object obj)	Return a content-based String representation if obj is not null; otherwise returns an empty String.
static String	getIdentityHexString(Object obj)	Return a hex String form of an object's identity hash code.
static String	identityToString(Object obj)	Return a String representation of an object's overall identity.
static boolean	isArray(Object obj)	Determine whether the given object is an array: either an Object array or a primitive array.
static boolean	isCheckedException(Throwable ex)	Return whether the given throwable is a checked exception: that is, neither a RuntimeException nor an Error.
static boolean	isCompatibleWithThrowsClause(Throwable ex, Class<?>... declaredExceptions)	Check whether the given exception is compatible with the specified exception types, as declared in a throws clause.
static boolean	isEmpty(Object obj)	Determine whether the given object is empty.
static boolean	isEmpty(Object[] array)	Determine whether the given array is empty: i.e.
static String	nullSafeClassName(Object obj)	Determine the class name for the given object.
static boolean	nullSafeEquals(Object o1, Object o2)	Determine if the given objects are equal, returning true if both are null or false if only one is null.
static int	nullSafeHashCode(boolean[] array)	Return a hash code based on the contents of the specified array.
static int	nullSafeHashCode(byte[] array)	Return a hash code based on the contents of the specified array.
static int	nullSafeHashCode(char[] array)	Return a hash code based on the contents of the specified array.
static int	nullSafeHashCode(double[] array)	Return a hash code based on the contents of the specified array.
static int	nullSafeHashCode(float[] array)	Return a hash code based on the contents of the specified array.
static int	nullSafeHashCode(int[] array)	Return a hash code based on the contents of the specified array.
static int	nullSafeHashCode(long[] array)	Return a hash code based on the contents of the specified array.
static int	nullSafeHashCode(short[] array)	Return a hash code based on the contents of the specified array.
static int	nullSafeHashCode(Object obj)	Return as hash code for the given object; typically the value of Object#hashCode()}.
static int	nullSafeHashCode(Object[] array)	Return a hash code based on the contents of the specified array.
static String	nullSafeToString(boolean[] array)	Return a String representation of the contents of the specified array.
static String	nullSafeToString(byte[] array)	Return a String representation of the contents of the specified array.
static String	nullSafeToString(char[] array)	Return a String representation of the contents of the specified array.
static String	nullSafeToString(double[] array)	Return a String representation of the contents of the specified array.
static String	nullSafeToString(float[] array)	Return a String representation of the contents of the specified array.
static String	nullSafeToString(int[] array)	Return a String representation of the contents of the specified array.
static String	nullSafeToString(long[] array)	Return a String representation of the contents of the specified array.
static String	nullSafeToString(short[] array)	Return a String representation of the contents of the specified array.
static String	nullSafeToString(Object obj)	Return a String representation of the specified Object.
static String	nullSafeToString(Object[] array)	Return a String representation of the contents of the specified array.
static Object[]	toObjectArray(Object source)	Convert the given array (which may be a primitive array) to an object array (if necessary of primitive wrapper objects).
static Object	unwrapOptional(Object obj)	Unwrap the given object which is potentially a Optional.

Methods inherited from class java.lang.Object

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

Constructor Details

ObjectUtils

public ObjectUtils()

Method Details

isCheckedException

public static boolean isCheckedException(Throwable ex)

Return whether the given throwable is a checked exception: that is, neither a RuntimeException nor an Error.

Parameters:

ex - the throwable to check

Returns:

whether the throwable is a checked exception

See Also:

• Exception
• RuntimeException
• Error

isCompatibleWithThrowsClause

public static boolean isCompatibleWithThrowsClause(Throwable ex,
 @Nullable
 Class<?>... declaredExceptions)

Check whether the given exception is compatible with the specified exception types, as declared in a throws clause.

Parameters:

ex - the exception to check

declaredExceptions - the exception types declared in the throws clause

Returns:

whether the given exception is compatible

isArray

public static boolean isArray(@Nullable
 Object obj)

Determine whether the given object is an array: either an Object array or a primitive array.

Parameters:

obj - the object to check

isEmpty

public static boolean isEmpty(@Nullable
 Object[] array)

Determine whether the given array is empty: i.e. null or of zero length.

Parameters:

array - the array to check

See Also:

• isEmpty(Object)

isEmpty

public static boolean isEmpty(@Nullable
 Object obj)

Determine whether the given object is empty.

This method supports the following object types.

• Optional: considered empty if not Optional.isPresent()
• Array: considered empty if its length is zero
• CharSequence: considered empty if its length is zero
• Collection: delegates to Collection.isEmpty()
• Map: delegates to Map.isEmpty()

If the given object is non-null and not one of the aforementioned supported types, this method returns false.

Parameters:

obj - the object to check

Returns:

true if the object is null or empty

Since:

4.2

See Also:

• Optional.isPresent()
• isEmpty(Object[])
• StringUtils.hasLength(CharSequence)
• CollectionUtils.isEmpty(java.util.Collection)
• CollectionUtils.isEmpty(java.util.Map)

unwrapOptional

@Nullable
public static Object unwrapOptional(@Nullable
 Object obj)

Unwrap the given object which is potentially a Optional.

Parameters:

obj - the candidate object

Returns:

either the value held within the Optional, null if the Optional is empty, or simply the given object as-is

Since:

5.0

containsElement

public static boolean containsElement(@Nullable
 Object[] array,
 Object element)

Check whether the given array contains the given element.

Parameters:

array - the array to check (may be null, in which case the return value will always be false)

element - the element to check for

Returns:

whether the element has been found in the given array

containsConstant

public static boolean containsConstant(Enum<?>[] enumValues,
 String constant)

Check whether the given array of enum constants contains a constant with the given name, ignoring case when determining a match.

Parameters:

enumValues - the enum values to check, typically obtained via MyEnum.values()

constant - the constant name to find (must not be null or empty string)

Returns:

whether the constant has been found in the given array

containsConstant

public static boolean containsConstant(Enum<?>[] enumValues,
 String constant,
 boolean caseSensitive)

Check whether the given array of enum constants contains a constant with the given name.

Parameters:

enumValues - the enum values to check, typically obtained via MyEnum.values()

constant - the constant name to find (must not be null or empty string)

caseSensitive - whether case is significant in determining a match

Returns:

whether the constant has been found in the given array

caseInsensitiveValueOf

public static <E extends Enum<?>> E caseInsensitiveValueOf(E[] enumValues,
 String constant)

Case insensitive alternative to Enum.valueOf(Class, String).

Type Parameters:

E - the concrete Enum type

Parameters:

enumValues - the array of all Enum constants in question, usually per Enum.values()

constant - the constant to get the enum value of

Throws:

IllegalArgumentException - if the given constant is not found in the given array of enum values. Use containsConstant(Enum[], String) as a guard to avoid this exception.

addObjectToArray

public static <A,
O extends A> A[] addObjectToArray(@Nullable
 A[] array,
 @Nullable
 O obj)

Append the given object to the given array, returning a new array consisting of the input array contents plus the given object.

Parameters:

array - the array to append to (can be null)

obj - the object to append

Returns:

the new array (of the same component type; never null)

toObjectArray

public static Object[] toObjectArray(@Nullable
 Object source)

Convert the given array (which may be a primitive array) to an object array (if necessary of primitive wrapper objects).

A null source value will be converted to an empty Object array.

Parameters:

source - the (potentially primitive) array

Returns:

the corresponding object array (never null)

Throws:

IllegalArgumentException - if the parameter is not an array

nullSafeEquals

public static boolean nullSafeEquals(@Nullable
 Object o1,
 @Nullable
 Object o2)

Determine if the given objects are equal, returning true if both are null or false if only one is null.

Compares arrays with Arrays.equals, performing an equality check based on the array elements rather than the array reference.

Parameters:

o1 - first Object to compare

o2 - second Object to compare

Returns:

whether the given objects are equal

See Also:

• Object.equals(Object)
• Arrays.equals(long[], long[])

nullSafeHashCode

public static int nullSafeHashCode(@Nullable
 Object obj)

Return as hash code for the given object; typically the value of Object#hashCode()}. If the object is an array, this method will delegate to any of the nullSafeHashCode methods for arrays in this class. If the object is null, this method returns 0.

See Also:

• Object.hashCode()
• nullSafeHashCode(Object[])
• nullSafeHashCode(boolean[])
• nullSafeHashCode(byte[])
• nullSafeHashCode(char[])
• nullSafeHashCode(double[])
• nullSafeHashCode(float[])
• nullSafeHashCode(int[])
• nullSafeHashCode(long[])
• nullSafeHashCode(short[])

nullSafeHashCode

public static int nullSafeHashCode(@Nullable
 Object[] array)

Return a hash code based on the contents of the specified array. If array is null, this method returns 0.

nullSafeHashCode

public static int nullSafeHashCode(@Nullable
 boolean[] array)

Return a hash code based on the contents of the specified array. If array is null, this method returns 0.

nullSafeHashCode

public static int nullSafeHashCode(@Nullable
 byte[] array)

Return a hash code based on the contents of the specified array. If array is null, this method returns 0.

nullSafeHashCode

public static int nullSafeHashCode(@Nullable
 char[] array)

Return a hash code based on the contents of the specified array. If array is null, this method returns 0.

nullSafeHashCode

public static int nullSafeHashCode(@Nullable
 double[] array)

Return a hash code based on the contents of the specified array. If array is null, this method returns 0.

nullSafeHashCode

public static int nullSafeHashCode(@Nullable
 float[] array)

Return a hash code based on the contents of the specified array. If array is null, this method returns 0.

nullSafeHashCode

public static int nullSafeHashCode(@Nullable
 int[] array)

Return a hash code based on the contents of the specified array. If array is null, this method returns 0.

nullSafeHashCode

public static int nullSafeHashCode(@Nullable
 long[] array)

Return a hash code based on the contents of the specified array. If array is null, this method returns 0.

nullSafeHashCode

public static int nullSafeHashCode(@Nullable
 short[] array)

Return a hash code based on the contents of the specified array. If array is null, this method returns 0.

identityToString

public static String identityToString(@Nullable
 Object obj)

Return a String representation of an object's overall identity.

Parameters:

obj - the object (may be null)

Returns:

the object's identity as String representation, or an empty String if the object was null

getIdentityHexString

public static String getIdentityHexString(Object obj)

Return a hex String form of an object's identity hash code.

Parameters:

obj - the object

Returns:

the object's identity code in hex notation

getDisplayString

public static String getDisplayString(@Nullable
 Object obj)

Return a content-based String representation if obj is not null; otherwise returns an empty String.

Differs from nullSafeToString(Object) in that it returns an empty String rather than "null" for a null value.

Parameters:

obj - the object to build a display String for

Returns:

a display String representation of obj

See Also:

• nullSafeToString(Object)

nullSafeClassName

public static String nullSafeClassName(@Nullable
 Object obj)

Determine the class name for the given object.

Returns a "null" String if obj is null.

Parameters:

obj - the object to introspect (may be null)

Returns:

the corresponding class name

nullSafeToString

public static String nullSafeToString(@Nullable
 Object obj)

Return a String representation of the specified Object.

Builds a String representation of the contents in case of an array. Returns a "null" String if obj is null.

Parameters:

obj - the object to build a String representation for

Returns:

a String representation of obj

nullSafeToString

public static String nullSafeToString(@Nullable
 Object[] array)

Return a String representation of the contents of the specified array.

The String representation consists of a list of the array's elements, enclosed in curly braces ("{}"). Adjacent elements are separated by the characters ", " (a comma followed by a space). Returns a "null" String if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static String nullSafeToString(@Nullable
 boolean[] array)

Return a String representation of the contents of the specified array.

The String representation consists of a list of the array's elements, enclosed in curly braces ("{}"). Adjacent elements are separated by the characters ", " (a comma followed by a space). Returns a "null" String if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static String nullSafeToString(@Nullable
 byte[] array)

Return a String representation of the contents of the specified array.

The String representation consists of a list of the array's elements, enclosed in curly braces ("{}"). Adjacent elements are separated by the characters ", " (a comma followed by a space). Returns a "null" String if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static String nullSafeToString(@Nullable
 char[] array)

Return a String representation of the contents of the specified array.

The String representation consists of a list of the array's elements, enclosed in curly braces ("{}"). Adjacent elements are separated by the characters ", " (a comma followed by a space). Returns a "null" String if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static String nullSafeToString(@Nullable
 double[] array)

Return a String representation of the contents of the specified array.

The String representation consists of a list of the array's elements, enclosed in curly braces ("{}"). Adjacent elements are separated by the characters ", " (a comma followed by a space). Returns a "null" String if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static String nullSafeToString(@Nullable
 float[] array)

Return a String representation of the contents of the specified array.

The String representation consists of a list of the array's elements, enclosed in curly braces ("{}"). Adjacent elements are separated by the characters ", " (a comma followed by a space). Returns a "null" String if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static String nullSafeToString(@Nullable
 int[] array)

Return a String representation of the contents of the specified array.

The String representation consists of a list of the array's elements, enclosed in curly braces ("{}"). Adjacent elements are separated by the characters ", " (a comma followed by a space). Returns a "null" String if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static String nullSafeToString(@Nullable
 long[] array)

Return a String representation of the contents of the specified array.

The String representation consists of a list of the array's elements, enclosed in curly braces ("{}"). Adjacent elements are separated by the characters ", " (a comma followed by a space). Returns a "null" String if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static String nullSafeToString(@Nullable
 short[] array)

Return a String representation of the contents of the specified array.

The String representation consists of a list of the array's elements, enclosed in curly braces ("{}"). Adjacent elements are separated by the characters ", " (a comma followed by a space). Returns a "null" String if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array