org.apache.commons.lang
Class ObjectUtils
Operations on
Object
.
This class tries to handle
null
input gracefully.
An exception will generally not be thrown for a
null
input.
Each method documents its behaviour in more detail.
$Id: ObjectUtils.java 161243 2005-04-14 04:30:28Z ggregory $static class | ObjectUtils.Null - Class used as a null placeholder where
null
has another meaning.
|
ObjectUtils() -
ObjectUtils instances should NOT be constructed in
standard programming.
|
static StringBuffer | appendIdentityToString(StringBuffer buffer, Object object) - Appends the toString that would be produced by
Object
if a class did not override toString itself.
|
static Object | defaultIfNull(Object object, Object defaultValue) - Returns a default value if the object passed is
null .
|
static boolean | equals(Object object1, Object object2) - Compares two objects for equality, where either one or both
objects may be
null .
|
static int | hashCode(Object obj) - Gets the hash code of an object returning zero when the
object is
null .
|
static String | identityToString(Object object) - Gets the toString that would be produced by
Object
if a class did not override toString itself.
|
static String | toString(Object obj) - Gets the
toString of an Object returning
an empty string ("") if null input.
|
static String | toString(Object obj, String nullStr) - Gets the
toString of an Object returning
a specified text if null input.
|
NULL
public static final ObjectUtils.Null NULL
Singleton used as a
null
placeholder where
null
has another meaning.
For example, in a
HashMap
the
HashMap.get(java.lang.Object)
method returns
null
if the
Map
contains
null
or if there is no matching key. The
Null
placeholder can be used to distinguish between
these two cases.
Another example is
Hashtable
, where
null
cannot be stored.
This instance is Serializable.
ObjectUtils
public ObjectUtils()
ObjectUtils
instances should NOT be constructed in
standard programming. Instead, the class should be used as
ObjectUtils.defaultIfNull("a","b");
.
This constructor is public to permit tools that require a JavaBean instance
to operate.
appendIdentityToString
public static StringBuffer appendIdentityToString(StringBuffer buffer,
Object object)
Appends the toString that would be produced by
Object
if a class did not override toString itself.
null
will return
null
.
ObjectUtils.appendIdentityToString(*, null) = null
ObjectUtils.appendIdentityToString(null, "") = "java.lang.String@1e23"
ObjectUtils.appendIdentityToString(null, Boolean.TRUE) = "java.lang.Boolean@7fa"
ObjectUtils.appendIdentityToString(buf, Boolean.TRUE) = buf.append("java.lang.Boolean@7fa")
buffer
- the buffer to append to, may be null
object
- the object to create a toString for, may be null
- the default toString text, or
null
if
null
passed in
defaultIfNull
public static Object defaultIfNull(Object object,
Object defaultValue)
Returns a default value if the object passed is
null
.
ObjectUtils.defaultIfNull(null, null) = null
ObjectUtils.defaultIfNull(null, "") = ""
ObjectUtils.defaultIfNull(null, "zz") = "zz"
ObjectUtils.defaultIfNull("abc", *) = "abc"
ObjectUtils.defaultIfNull(Boolean.TRUE, *) = Boolean.TRUE
object
- the Object
to test, may be null
defaultValue
- the default value to return, may be null
object
if it is not null
, defaultValue otherwise
equals
public static boolean equals(Object object1,
Object object2)
Compares two objects for equality, where either one or both
objects may be
null
.
ObjectUtils.equals(null, null) = true
ObjectUtils.equals(null, "") = false
ObjectUtils.equals("", null) = false
ObjectUtils.equals("", "") = true
ObjectUtils.equals(Boolean.TRUE, null) = false
ObjectUtils.equals(Boolean.TRUE, "true") = false
ObjectUtils.equals(Boolean.TRUE, Boolean.TRUE) = true
ObjectUtils.equals(Boolean.TRUE, Boolean.FALSE) = false
object1
- the first object, may be null
object2
- the second object, may be null
true
if the values of both objects are the same
hashCode
public static int hashCode(Object obj)
Gets the hash code of an object returning zero when the
object is
null
.
ObjectUtils.hashCode(null) = 0
ObjectUtils.hashCode(obj) = obj.hashCode()
obj
- the object to obtain the hash code of, may be null
- the hash code of the object, or zero if null
identityToString
public static String identityToString(Object object)
Gets the toString that would be produced by
Object
if a class did not override toString itself.
null
will return
null
.
ObjectUtils.identityToString(null) = null
ObjectUtils.identityToString("") = "java.lang.String@1e23"
ObjectUtils.identityToString(Boolean.TRUE) = "java.lang.Boolean@7fa"
object
- the object to create a toString for, may be
null
- the default toString text, or
null
if
null
passed in
toString
public static String toString(Object obj)
Gets the
toString
of an
Object
returning
an empty string ("") if
null
input.
ObjectUtils.toString(null) = ""
ObjectUtils.toString("") = ""
ObjectUtils.toString("bat") = "bat"
ObjectUtils.toString(Boolean.TRUE) = "true"
obj
- the Object to toString
, may be null
- the passed in Object's toString, or nullStr if
null
input
toString
public static String toString(Object obj,
String nullStr)
Gets the
toString
of an
Object
returning
a specified text if
null
input.
ObjectUtils.toString(null, null) = null
ObjectUtils.toString(null, "null") = "null"
ObjectUtils.toString("", "null") = ""
ObjectUtils.toString("bat", "null") = "bat"
ObjectUtils.toString(Boolean.TRUE, "null") = "true"
obj
- the Object to toString
, may be nullnullStr
- the String to return if null
input, may be null
- the passed in Object's toString, or nullStr if
null
input
Copyright © 2001-2005 - Apache Software Foundation