org.apache.commons.lang.ObjectUtils

This class tries to handle null input gracefully. An exception will generally not be thrown for a null input. Each method documents its behavior in more detail.

Nested Class Summary

static class ObjectUtils.Null

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

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 public static java.lang.Object defaultIfNull(java.lang.Object object, java.lang.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 

Parameters: objectthe Object to test, may be null

defaultValuethe default value to return, may be null

Returns: object if it is not null, defaultValue otherwise

 public static boolean equals(java.lang.Object object1, java.lang.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 

Parameters: object1the first object, may be null

object2the second object, may be null

Returns: true if the values of both objects are the same

 public static java.lang.String identityToString(java.lang.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" 

Parameters: objectthe object to create a toString for, may be null

Returns: the default toString text, or null if null passed in

 public static java.lang.StringBuffer appendIdentityToString(java.lang.StringBuffer buffer, java.lang.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") 

Parameters: bufferthe buffer to append to, may be null

objectthe object to create a toString for, may be null

Returns: the default toString text, or null if null passed in

 public static java.lang.String toString(java.lang.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" 

Parameters: objthe Object to toString, may be null

Returns: the passed in Object's toString, or nullStr if null input

See Also: StringUtils.defaultString(String), String.valueOf(Object)

 public static java.lang.String toString(java.lang.Object obj, java.lang.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" 

Parameters: objthe Object to toString, may be null

nullStrthe String to return if null input, may be null

Returns: the passed in Object's toString, or nullStr if null input

See Also: StringUtils.defaultString(String,String), String.valueOf(Object)