Package org.apache.wicket.util.lang

Class Objects

java.lang.Object

org.apache.wicket.util.lang.Objects

public final class Objects
extends Object

Object utilities.

Author:

Jonathan Locke

Method Summary

Modifier and Type	Method	Description
static BigDecimal	bigDecValue(Object value)	Evaluates the given object as a BigDecimal.
static BigInteger	bigIntValue(Object value)	Evaluates the given object as a BigInteger.
static boolean	booleanValue(Object value)	Evaluates the given object as a boolean: if it is a Boolean object, it's easy; if it's a Number or a Character, returns true for non-zero objects; and otherwise returns true for non-null objects.
static int	compareWithConversion(Object v1, Object v2)	Compares two objects for equality, even if it has to convert one of them to the other type.
static <T> T	convertValue(Object value, Class<T> toType)	Convert between basic Java types, i.e.
static <T> T	defaultIfNull(T originalObj, T defaultObj)	Returns the original object if this one is != null.
static double	doubleValue(Object value)	Evaluates the given object as a double-precision floating-point number.
static boolean	equal(Object a, Object b)	Returns true if a and b are equal.
static int	getNumericType(int t1, int t2, boolean canBeNonNumeric)	Returns the constant from the NumericTypes interface that best expresses the type of an operation, which can be either numeric or not, on the two given types.
static int	getNumericType(Object value)	Returns a constant from the NumericTypes interface that represents the numeric type of the given object.
static int	getNumericType(Object v1, Object v2)	Returns the constant from the NumericTypes interface that best expresses the type of a numeric operation on the two given objects.
static int	getNumericType(Object v1, Object v2, boolean canBeNonNumeric)	Returns the constant from the NumericTypes interface that best expresses the type of an operation, which can be either numeric or not, on the two given objects.
static int	hashCode(Object... obj)	returns hashcode of the objects by calling obj.hashcode().
static boolean	isEqual(Object object1, Object object2)	Returns true if object1 is equal to object2 in either the sense that they are the same object or, if both are non-null if they are equal in the equals() sense.
static long	longValue(Object value)	Evaluates the given object as a long integer.
static Number	newInteger(int type, long value)	Returns a new Number object of an appropriate type to hold the given integer value.
static String	stringValue(Object value)	Evaluates the given object as a String.
static String	stringValue(Object value, boolean trim)	Evaluates the given object as a String and trims it if the trim flag is true.

Methods inherited from class java.lang.Object

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

Method Detail

bigDecValue

public static BigDecimal bigDecValue(Object value)
                              throws NumberFormatException

Evaluates the given object as a BigDecimal.

Parameters:

value - an object to interpret as a BigDecimal

Returns:

the BigDecimal value implied by the given object

Throws:

NumberFormatException - if the given object can't be understood as a BigDecimal

bigIntValue

public static BigInteger bigIntValue(Object value)
                              throws NumberFormatException

Evaluates the given object as a BigInteger.

Parameters:

value - an object to interpret as a BigInteger

Returns:

the BigInteger value implied by the given object

Throws:

NumberFormatException - if the given object can't be understood as a BigInteger

booleanValue

public static boolean booleanValue(Object value)

Evaluates the given object as a boolean: if it is a Boolean object, it's easy; if it's a Number or a Character, returns true for non-zero objects; and otherwise returns true for non-null objects.

Parameters:

value - an object to interpret as a boolean

Returns:

the boolean value implied by the given object

compareWithConversion

public static int compareWithConversion(Object v1,
                                        Object v2)

Compares two objects for equality, even if it has to convert one of them to the other type. If both objects are numeric they are converted to the widest type and compared. If one is non-numeric and one is numeric the non-numeric is converted to double and compared to the double numeric value. If both are non-numeric and Comparable and the types are compatible (i.e. v1 is of the same or superclass of v2's type) they are compared with Comparable.compareTo(). If both values are non-numeric and not Comparable or of incompatible classes this will throw and IllegalArgumentException.

Parameters:

v1 - First value to compare

v2 - second value to compare

Returns:

integer describing the comparison between the two objects. A negative number indicates that v1 < v2. Positive indicates that v1 > v2. Zero indicates v1 == v2.

Throws:

IllegalArgumentException - if the objects are both non-numeric yet of incompatible types or do not implement Comparable.

convertValue

public static <T> T convertValue(Object value,
                                 Class<T> toType)

Convert between basic Java types, i.e. primitives and their wrappers, numbers and strings.

This method also detects when arrays are being converted and converts the components of one array to the type of the other.

Type Parameters:

T - target type

Parameters:

value - an object to be converted to the given type

toType - class type to be converted to

Returns:

converted value of the type given, or null if the value cannot be converted to the given type.

doubleValue

public static double doubleValue(Object value)
                          throws NumberFormatException

Evaluates the given object as a double-precision floating-point number.

Parameters:

value - an object to interpret as a double

Returns:

the double value implied by the given object

Throws:

NumberFormatException - if the given object can't be understood as a double

equal

public static boolean equal(Object a,
                            Object b)

Returns true if a and b are equal. Either object may be null.

Parameters:

a - Object a

b - Object b

Returns:

True if the objects are equal

getNumericType

public static int getNumericType(int t1,
                                 int t2,
                                 boolean canBeNonNumeric)

Returns the constant from the NumericTypes interface that best expresses the type of an operation, which can be either numeric or not, on the two given types.

Parameters:

t1 - type of one argument to an operator

t2 - type of the other argument

canBeNonNumeric - whether the operator can be interpreted as non-numeric

Returns:

the appropriate constant from the NumericTypes interface

getNumericType

public static int getNumericType(Object value)

Returns a constant from the NumericTypes interface that represents the numeric type of the given object.

Parameters:

value - an object that needs to be interpreted as a number

Returns:

the appropriate constant from the NumericTypes interface

getNumericType

public static int getNumericType(Object v1,
                                 Object v2)

Returns the constant from the NumericTypes interface that best expresses the type of a numeric operation on the two given objects.

Parameters:

v1 - one argument to a numeric operator

v2 - the other argument

Returns:

the appropriate constant from the NumericTypes interface

getNumericType

public static int getNumericType(Object v1,
                                 Object v2,
                                 boolean canBeNonNumeric)

Returns the constant from the NumericTypes interface that best expresses the type of an operation, which can be either numeric or not, on the two given objects.

Parameters:

v1 - one argument to an operator

v2 - the other argument

canBeNonNumeric - whether the operator can be interpreted as non-numeric

Returns:

the appropriate constant from the NumericTypes interface

isEqual

public static boolean isEqual(Object object1,
                              Object object2)

Returns true if object1 is equal to object2 in either the sense that they are the same object or, if both are non-null if they are equal in the equals() sense.

Parameters:

object1 - First object to compare

object2 - Second object to compare

Returns:

true if v1 == v2

longValue

public static long longValue(Object value)
                      throws NumberFormatException

Evaluates the given object as a long integer.

Parameters:

value - an object to interpret as a long integer

Returns:

the long integer value implied by the given object

Throws:

NumberFormatException - if the given object can't be understood as a long integer

newInteger

public static Number newInteger(int type,
                                long value)

Returns a new Number object of an appropriate type to hold the given integer value. The type of the returned object is consistent with the given type argument, which is a constant from the NumericTypes interface.

Parameters:

type - the nominal numeric type of the result, a constant from the NumericTypes interface

value - the integer value to convert to a Number object

Returns:

a Number object with the given value, of type implied by the type argument

stringValue

public static String stringValue(Object value)

Evaluates the given object as a String.

Parameters:

value - an object to interpret as a String

Returns:

the String value implied by the given object as returned by the toString() method, or "null" if the object is null.

hashCode

public static int hashCode(Object... obj)

returns hashcode of the objects by calling obj.hashcode(). safe to use when obj is null.

Parameters:

obj -

Returns:

hashcode of the object or 0 if obj is null

stringValue

public static String stringValue(Object value,
                                 boolean trim)

Evaluates the given object as a String and trims it if the trim flag is true.

Parameters:

value - an object to interpret as a String

trim - whether to trim the string

Returns:

the String value implied by the given object as returned by the toString() method, or "null" if the object is null.

defaultIfNull

public static <T> T defaultIfNull(T originalObj,
                                  T defaultObj)

Returns the original object if this one is != null. If the original object is null the default one is returned. The default object has no restriction, it might be itself null.

Parameters:

originalObj - the original object

defaultObj - the default object

Returns:

the original object if not null, the default one otherwise.