org.springframework.util
Class ObjectUtils

java.lang.Object
  org.springframework.util.ObjectUtils

public abstract class ObjectUtils
extends java.lang.Object

Miscellaneous object utility methods.

Mainly for internal use within the framework; consider Jakarta's Commons Lang for a more comprehensive suite of object utilities.

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

See Also:

org.apache.commons.lang.ObjectUtils

Field Summary

private static java.lang.String	ARRAY_ELEMENT_SEPARATOR
private static java.lang.String	ARRAY_END
private static java.lang.String	ARRAY_START
private static java.lang.String	EMPTY_ARRAY
private static java.lang.String	EMPTY_STRING
private static int	INITIAL_HASH
private static int	MULTIPLIER
private static java.lang.String	NULL_STRING

Constructor Summary

ObjectUtils()

Method Summary

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 java.lang.Enum<?>> E	caseInsensitiveValueOf(E[] enumValues, java.lang.String constant) Case insensitive alternative to Enum.valueOf(Class, String).
static boolean	containsConstant(java.lang.Enum<?>[] enumValues, java.lang.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(java.lang.Enum<?>[] enumValues, java.lang.String constant, boolean caseSensitive) Check whether the given array of enum constants contains a constant with the given name.
static boolean	containsElement(java.lang.Object[] array, java.lang.Object element) Check whether the given array contains the given element.
static java.lang.String	getDisplayString(java.lang.Object obj) Return a content-based String representation if obj is not null; otherwise returns an empty String.
static java.lang.String	getIdentityHexString(java.lang.Object obj) Return a hex String form of an object's identity hash code.
static int	hashCode(boolean bool) Return the same value as Boolean.hashCode().
static int	hashCode(double dbl) Return the same value as Double.hashCode().
static int	hashCode(float flt) Return the same value as Float.hashCode().
static int	hashCode(long lng) Return the same value as Long.hashCode().
static java.lang.String	identityToString(java.lang.Object obj) Return a String representation of an object's overall identity.
static boolean	isArray(java.lang.Object obj) Determine whether the given object is an array: either an Object array or a primitive array.
static boolean	isCheckedException(java.lang.Throwable ex) Return whether the given throwable is a checked exception: that is, neither a RuntimeException nor an Error.
static boolean	isCompatibleWithThrowsClause(java.lang.Throwable ex, java.lang.Class[] declaredExceptions) Check whether the given exception is compatible with the exceptions declared in a throws clause.
static boolean	isEmpty(java.lang.Object[] array) Determine whether the given array is empty: i.e.
static java.lang.String	nullSafeClassName(java.lang.Object obj) Determine the class name for the given object.
static boolean	nullSafeEquals(java.lang.Object o1, java.lang.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(java.lang.Object obj) Return as hash code for the given object; typically the value of Object.hashCode().
static int	nullSafeHashCode(java.lang.Object[] 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 java.lang.String	nullSafeToString(boolean[] array) Return a String representation of the contents of the specified array.
static java.lang.String	nullSafeToString(byte[] array) Return a String representation of the contents of the specified array.
static java.lang.String	nullSafeToString(char[] array) Return a String representation of the contents of the specified array.
static java.lang.String	nullSafeToString(double[] array) Return a String representation of the contents of the specified array.
static java.lang.String	nullSafeToString(float[] array) Return a String representation of the contents of the specified array.
static java.lang.String	nullSafeToString(int[] array) Return a String representation of the contents of the specified array.
static java.lang.String	nullSafeToString(long[] array) Return a String representation of the contents of the specified array.
static java.lang.String	nullSafeToString(java.lang.Object obj) Return a String representation of the specified Object.
static java.lang.String	nullSafeToString(java.lang.Object[] array) Return a String representation of the contents of the specified array.
static java.lang.String	nullSafeToString(short[] array) Return a String representation of the contents of the specified array.
static java.lang.Object[]	toObjectArray(java.lang.Object source) Convert the given array (which may be a primitive array) to an object array (if necessary of primitive wrapper objects).

Methods inherited from class java.lang.Object

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

Field Detail

INITIAL_HASH

private static final int INITIAL_HASH

See Also:

Constant Field Values

MULTIPLIER

private static final int MULTIPLIER

See Also:

Constant Field Values

EMPTY_STRING

private static final java.lang.String EMPTY_STRING

See Also:

Constant Field Values

NULL_STRING

private static final java.lang.String NULL_STRING

See Also:

Constant Field Values

ARRAY_START

private static final java.lang.String ARRAY_START

See Also:

Constant Field Values

ARRAY_END

private static final java.lang.String ARRAY_END

See Also:

Constant Field Values

EMPTY_ARRAY

private static final java.lang.String EMPTY_ARRAY

See Also:

Constant Field Values

ARRAY_ELEMENT_SEPARATOR

private static final java.lang.String ARRAY_ELEMENT_SEPARATOR

See Also:

Constant Field Values

Constructor Detail

ObjectUtils

public ObjectUtils()

Method Detail

isCheckedException

public static boolean isCheckedException(java.lang.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(java.lang.Throwable ex,
                                                   java.lang.Class[] declaredExceptions)

Check whether the given exception is compatible with the exceptions declared in a throws clause.

Parameters:

ex - the exception to checked

declaredExceptions - the exceptions declared in the throws clause

Returns:

whether the given exception is compatible

isArray

public static boolean isArray(java.lang.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(java.lang.Object[] array)

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

Parameters:

array - the array to check

containsElement

public static boolean containsElement(java.lang.Object[] array,
                                      java.lang.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(java.lang.Enum<?>[] enumValues,
                                       java.lang.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 the product of a call to 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(java.lang.Enum<?>[] enumValues,
                                       java.lang.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 the product of a call to 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 java.lang.Enum<?>> E caseInsensitiveValueOf(E[] enumValues,
                                                                     java.lang.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:

java.lang.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(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.

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 java.lang.Object[] toObjectArray(java.lang.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:

java.lang.IllegalArgumentException - if the parameter is not an array

nullSafeEquals

public static boolean nullSafeEquals(java.lang.Object o1,
                                     java.lang.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:

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

nullSafeHashCode

public static int nullSafeHashCode(java.lang.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:

nullSafeHashCode(Object[]), nullSafeHashCode(boolean[]), nullSafeHashCode(byte[]), nullSafeHashCode(char[]), nullSafeHashCode(double[]), nullSafeHashCode(float[]), nullSafeHashCode(int[]), nullSafeHashCode(long[]), nullSafeHashCode(short[])

nullSafeHashCode

public static int nullSafeHashCode(java.lang.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(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(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(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(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(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(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(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(short[] array)

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

hashCode

public static int hashCode(boolean bool)

Return the same value as Boolean.hashCode().

See Also:

Boolean.hashCode()

hashCode

public static int hashCode(double dbl)

Return the same value as Double.hashCode().

See Also:

Double.hashCode()

hashCode

public static int hashCode(float flt)

Return the same value as Float.hashCode().

See Also:

Float.hashCode()

hashCode

public static int hashCode(long lng)

Return the same value as Long.hashCode().

See Also:

Long.hashCode()

identityToString

public static java.lang.String identityToString(java.lang.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 java.lang.String getIdentityHexString(java.lang.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 java.lang.String getDisplayString(java.lang.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 java.lang.String nullSafeClassName(java.lang.Object obj)

Determine the class name for the given object.

Returns "null" if obj is null.

Parameters:

obj - the object to introspect (may be null)

Returns:

the corresponding class name

nullSafeToString

public static java.lang.String nullSafeToString(java.lang.Object obj)

Return a String representation of the specified Object.

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

Parameters:

obj - the object to build a String representation for

Returns:

a String representation of obj

nullSafeToString

public static java.lang.String nullSafeToString(java.lang.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 "null" if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static java.lang.String nullSafeToString(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 "null" if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static java.lang.String nullSafeToString(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 "null" if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static java.lang.String nullSafeToString(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 "null" if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static java.lang.String nullSafeToString(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 "null" if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static java.lang.String nullSafeToString(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 "null" if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static java.lang.String nullSafeToString(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 "null" if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static java.lang.String nullSafeToString(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 "null" if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array

nullSafeToString

public static java.lang.String nullSafeToString(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 "null" if array is null.

Parameters:

array - the array to build a String representation for

Returns:

a String representation of array