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java.lang.Object | +--org.apache.commons.lang.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.
| Inner Class Summary | |
static class |
ObjectUtils.Null
Class used as a null placeholder where null
has another meaning. |
| Field Summary | |
static ObjectUtils.Null |
NULL
Singleton used as a null placeholder where
null has another meaning. |
| Constructor Summary | |
ObjectUtils()
ObjectUtils instances should NOT be constructed in
standard programming. |
|
| Method Summary | |
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. |
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Field Detail |
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.
| Constructor Detail |
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.
| Method Detail |
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 nulldefaultValue - the default value to return, may be nullobject if it is not null, defaultValue otherwise
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 nullobject2 - the second object, may be nulltrue if the values of both objects are the samepublic 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 nullpublic 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
nullnull if
null passed in
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 nullobject - the object to create a toString for, may be nullnull if
null passed inpublic 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 nullnull inputStringUtils.defaultString(String),
String.valueOf(Object)
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 nullnull inputStringUtils.defaultString(String,String),
String.valueOf(Object)
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