| java.lang.Object
 org.apache.commons.lang.ObjectUtils
| ObjectUtils | | public class ObjectUtils (Code) | | 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.
author:
Nissim Karpenstein
author:
Janek Bogucki
author:
Daniel Rall
author:
Stephen Colebourne
author:
Gary Gregory
author:
Mario Winterer
author:
David J. M. Karlsen
since:
1.0
version:
$Id: ObjectUtils.java 491050 2006-12-29 17:04:00Z scolebourne $ |
| Inner Class :public static class Null implements Serializable | |
| Field Summary | |
| final public static Null | NULL
Singleton used as a null placeholder where
null has another meaning.
For example, in a HashMap the
java.util.HashMap.get(java.lang.Object) method returns
null if the Map contains
null or if there is no matching key. |
| Constructor Summary | |
| public | ObjectUtils()
ObjectUtils instances should NOT be constructed in
standard programming.
|
| NULL | | final public static Null NULL(Code) | | Singleton used as a null placeholder where
null has another meaning.
For example, in a HashMap the
java.util.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()(Code) | | 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)(Code) | | 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")
Parameters:
buffer - the buffer to append to, may be null
Parameters:
object - the object to create a toString for, may be null the default toString text, or null ifnull passed in
since:
2.0 |
| defaultIfNull | | public static Object defaultIfNull(Object object, Object defaultValue)(Code) | | 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
Parameters:
object - the Object to test, may be null
Parameters:
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)(Code) | | 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
Parameters:
object1 - the first object, may be null
Parameters:
object2 - the second object, may be null true if the values of both objects are the same |
| hashCode | | public static int hashCode(Object obj)(Code) | | Gets the hash code of an object returning zero when the
object is null.
ObjectUtils.hashCode(null) = 0
ObjectUtils.hashCode(obj) = obj.hashCode()
Parameters:
obj - the object to obtain the hash code of, may be null the hash code of the object, or zero if null
since:
2.1 |
| identityToString | | public static String identityToString(Object object)(Code) | | 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"
Parameters:
object - the object to create a toString for, may benull the default toString text, or null ifnull passed in |
| max | | public static Object max(Comparable c1, Comparable c2)(Code) | | Null safe comparison of Comparables.
Parameters:
c1 - the first comparable, may be null
Parameters:
c2 - the second comparable, may be null- If both objects are non-null and unequal, the greater object.
- If both objects are non-null and equal, c1.
- If one of the comparables is null, the non-null object.
- If both the comparables are null, null is returned.
|
| min | | public static Object min(Comparable c1, Comparable c2)(Code) | | Null safe comparison of Comparables.
Parameters:
c1 - the first comparable, may be null
Parameters:
c2 - the second comparable, may be null- If both objects are non-null and unequal, the lesser object.
- If both objects are non-null and equal, c1.
- If one of the comparables is null, the non-null object.
- If both the comparables are null, null is returned.
|
| toString | | public static String toString(Object obj)(Code) | | 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"
See Also: StringUtils.defaultString(String)
See Also: String.valueOf(Object)
Parameters:
obj - the Object to toString, may be null the passed in Object's toString, or nullStr if null input
since:
2.0 |
| toString | | public static String toString(Object obj, String nullStr)(Code) | | 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"
See Also: StringUtils.defaultString(StringString)
See Also: String.valueOf(Object)
Parameters:
obj - the Object to toString, may be null
Parameters:
nullStr - the String to return if null input, may be null the passed in Object's toString, or nullStr if null input
since:
2.0 |
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