public class ObjectUtils extends Object
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.
#ThreadSafe#
| Modifier and Type | Class and Description |
|---|---|
static class |
ObjectUtils.Null
Class used as a null placeholder where
null
has another meaning. |
| Modifier and Type | Field and Description |
|---|---|
static ObjectUtils.Null |
NULL
Singleton used as a
null placeholder where
null has another meaning. |
| Constructor and Description |
|---|
ObjectUtils()
ObjectUtils instances should NOT be constructed in
standard programming. |
| Modifier and Type | Method and Description |
|---|---|
static <T> T |
clone(T obj)
Clone an object.
|
static <T> T |
cloneIfPossible(T obj)
Clone an object if possible.
|
static <T extends Comparable<? super T>> |
compare(T c1,
T c2)
Null safe comparison of Comparables.
|
static <T extends Comparable<? super T>> |
compare(T c1,
T c2,
boolean nullGreater)
Null safe comparison of Comparables.
|
static byte |
CONST_BYTE(int v)
This method returns the provided value unchanged.
|
static short |
CONST_SHORT(int v)
This method returns the provided value unchanged.
|
static boolean |
CONST(boolean v)
This method returns the provided value unchanged.
|
static byte |
CONST(byte v)
This method returns the provided value unchanged.
|
static char |
CONST(char v)
This method returns the provided value unchanged.
|
static double |
CONST(double v)
This method returns the provided value unchanged.
|
static float |
CONST(float v)
This method returns the provided value unchanged.
|
static int |
CONST(int v)
This method returns the provided value unchanged.
|
static long |
CONST(long v)
This method returns the provided value unchanged.
|
static short |
CONST(short v)
This method returns the provided value unchanged.
|
static <T> T |
CONST(T v)
This method returns the provided value unchanged.
|
static <T> T |
defaultIfNull(T object,
T defaultValue)
Returns a default value if the object passed is
null. |
static boolean |
equals(Object object1,
Object object2)
Deprecated.
this method has been replaced by
java.util.Objects.equals(Object, Object) in Java 7 and will
be removed from future releases. |
static <T> T |
firstNonNull(T... values)
Returns the first value in the array which is not
null. |
static int |
hashCode(Object obj)
Deprecated.
this method has been replaced by
java.util.Objects.hashCode(Object) in Java 7 and will be
removed in future releases |
static int |
hashCodeMulti(Object... objects)
Deprecated.
this method has been replaced by
java.util.Objects.hash(Object...) in Java 7 and will be
removed in future releases. |
static void |
identityToString(Appendable appendable,
Object object)
Appends the toString that would be produced by
Object
if a class did not override toString itself. |
static String |
identityToString(Object object)
Gets the toString that would be produced by
Object
if a class did not override toString itself. |
static void |
identityToString(StrBuilder builder,
Object object)
Appends the toString that would be produced by
Object
if a class did not override toString itself. |
static void |
identityToString(StringBuffer buffer,
Object object)
Appends the toString that would be produced by
Object
if a class did not override toString itself. |
static void |
identityToString(StringBuilder builder,
Object object)
Appends the toString that would be produced by
Object
if a class did not override toString itself. |
static <T extends Comparable<? super T>> |
max(T... values)
Null safe comparison of Comparables.
|
static <T> T |
median(Comparator<T> comparator,
T... items)
Find the "best guess" middle value among comparables.
|
static <T extends Comparable<? super T>> |
median(T... items)
Find the "best guess" middle value among comparables.
|
static <T extends Comparable<? super T>> |
min(T... values)
Null safe comparison of Comparables.
|
static <T> T |
mode(T... items)
Find the most frequently occurring item.
|
static boolean |
notEqual(Object object1,
Object object2)
Compares two objects for inequality, where either one or both
objects may be
null. |
static String |
toString(Object obj)
Deprecated.
this method has been replaced by
java.util.Objects.toString(Object) in Java 7 and will be
removed in future releases. Note however that said method will return "null" for null references, while this
method returns and empty String. To preserve behavior use java.util.Objects.toString(myObject, "") |
static String |
toString(Object obj,
String nullStr)
Deprecated.
this method has been replaced by
java.util.Objects.toString(Object, String) in Java 7 and
will be removed in future releases. |
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.
public ObjectUtils()
ObjectUtils instances should NOT be constructed in
standard programming. Instead, the static methods on the class should
be used, such as ObjectUtils.defaultIfNull("a","b");.
This constructor is public to permit tools that require a JavaBean instance to operate.
public static <T> T defaultIfNull(T object, T 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
T - the type of the objectobject - the Object to test, may be nulldefaultValue - the default value to return, may be nullobject if it is not null, defaultValue otherwisepublic static <T> T firstNonNull(T... values)
Returns the first value in the array which is not null.
If all the values are null or the array is null
or empty then null is returned.
ObjectUtils.firstNonNull(null, null) = null
ObjectUtils.firstNonNull(null, "") = ""
ObjectUtils.firstNonNull(null, null, "") = ""
ObjectUtils.firstNonNull(null, "zz") = "zz"
ObjectUtils.firstNonNull("abc", *) = "abc"
ObjectUtils.firstNonNull(null, "xyz", *) = "xyz"
ObjectUtils.firstNonNull(Boolean.TRUE, *) = Boolean.TRUE
ObjectUtils.firstNonNull() = null
T - the component type of the arrayvalues - the values to test, may be null or emptyvalues which is not null,
or null if there are no non-null values@Deprecated public static boolean equals(Object object1, Object object2)
java.util.Objects.equals(Object, Object) in Java 7 and will
be removed from future releases.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 boolean notEqual(Object object1, Object object2)
Compares two objects for inequality, where either one or both
objects may be null.
ObjectUtils.notEqual(null, null) = false
ObjectUtils.notEqual(null, "") = true
ObjectUtils.notEqual("", null) = true
ObjectUtils.notEqual("", "") = false
ObjectUtils.notEqual(Boolean.TRUE, null) = true
ObjectUtils.notEqual(Boolean.TRUE, "true") = true
ObjectUtils.notEqual(Boolean.TRUE, Boolean.TRUE) = false
ObjectUtils.notEqual(Boolean.TRUE, Boolean.FALSE) = true
object1 - the first object, may be nullobject2 - the second object, may be nullfalse if the values of both objects are the same@Deprecated public static int hashCode(Object obj)
java.util.Objects.hashCode(Object) in Java 7 and will be
removed in future releasesGets 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@Deprecated public static int hashCodeMulti(Object... objects)
java.util.Objects.hash(Object...) in Java 7 and will be
removed in future releases.Gets the hash code for multiple objects.
This allows a hash code to be rapidly calculated for a number of objects.
The hash code for a single object is the not same as hashCode(Object).
The hash code for multiple objects is the same as that calculated by an
ArrayList containing the specified objects.
ObjectUtils.hashCodeMulti() = 1 ObjectUtils.hashCodeMulti((Object[]) null) = 1 ObjectUtils.hashCodeMulti(a) = 31 + a.hashCode() ObjectUtils.hashCodeMulti(a,b) = (31 + a.hashCode()) * 31 + b.hashCode() ObjectUtils.hashCodeMulti(a,b,c) = ((31 + a.hashCode()) * 31 + b.hashCode()) * 31 + c.hashCode()
objects - the objects 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 inpublic static void identityToString(Appendable appendable, Object object) throws IOException
Appends the toString that would be produced by Object
if a class did not override toString itself. null
will throw a NullPointerException for either of the two parameters.
ObjectUtils.identityToString(appendable, "") = appendable.append("java.lang.String@1e23"
ObjectUtils.identityToString(appendable, Boolean.TRUE) = appendable.append("java.lang.Boolean@7fa"
ObjectUtils.identityToString(appendable, Boolean.TRUE) = appendable.append("java.lang.Boolean@7fa")
appendable - the appendable to append toobject - the object to create a toString forIOException - if an I/O error occurspublic static void identityToString(StrBuilder builder, Object object)
Appends the toString that would be produced by Object
if a class did not override toString itself. null
will throw a NullPointerException for either of the two parameters.
ObjectUtils.identityToString(builder, "") = builder.append("java.lang.String@1e23"
ObjectUtils.identityToString(builder, Boolean.TRUE) = builder.append("java.lang.Boolean@7fa"
ObjectUtils.identityToString(builder, Boolean.TRUE) = builder.append("java.lang.Boolean@7fa")
builder - the builder to append toobject - the object to create a toString forpublic static void identityToString(StringBuffer buffer, Object object)
Appends the toString that would be produced by Object
if a class did not override toString itself. null
will throw a NullPointerException for either of the two parameters.
ObjectUtils.identityToString(buf, "") = buf.append("java.lang.String@1e23"
ObjectUtils.identityToString(buf, Boolean.TRUE) = buf.append("java.lang.Boolean@7fa"
ObjectUtils.identityToString(buf, Boolean.TRUE) = buf.append("java.lang.Boolean@7fa")
buffer - the buffer to append toobject - the object to create a toString forpublic static void identityToString(StringBuilder builder, Object object)
Appends the toString that would be produced by Object
if a class did not override toString itself. null
will throw a NullPointerException for either of the two parameters.
ObjectUtils.identityToString(builder, "") = builder.append("java.lang.String@1e23"
ObjectUtils.identityToString(builder, Boolean.TRUE) = builder.append("java.lang.Boolean@7fa"
ObjectUtils.identityToString(builder, Boolean.TRUE) = builder.append("java.lang.Boolean@7fa")
builder - the builder to append toobject - the object to create a toString for@Deprecated public static String toString(Object obj)
java.util.Objects.toString(Object) in Java 7 and will be
removed in future releases. Note however that said method will return "null" for null references, while this
method returns and empty String. To preserve behavior use java.util.Objects.toString(myObject, "")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"" if null inputStringUtils.defaultString(String),
String.valueOf(Object)@Deprecated public static String toString(Object obj, String nullStr)
java.util.Objects.toString(Object, String) in Java 7 and
will be removed in future releases.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 nullnullStr if null inputStringUtils.defaultString(String,String),
String.valueOf(Object)public static <T extends Comparable<? super T>> T min(T... values)
Null safe comparison of Comparables.
T - type of the values processed by this methodvalues - the set of comparable values, may be nullpublic static <T extends Comparable<? super T>> T max(T... values)
Null safe comparison of Comparables.
T - type of the values processed by this methodvalues - the set of comparable values, may be nullpublic static <T extends Comparable<? super T>> int compare(T c1, T c2)
Null safe comparison of Comparables.
null is assumed to be less than a non-null value.
T - type of the values processed by this methodc1 - the first comparable, may be nullc2 - the second comparable, may be nullpublic static <T extends Comparable<? super T>> int compare(T c1, T c2, boolean nullGreater)
Null safe comparison of Comparables.
T - type of the values processed by this methodc1 - the first comparable, may be nullc2 - the second comparable, may be nullnullGreater - if true null is considered greater
than a non-null value or if false null is
considered less than a Non-null valueComparator.compare(Object, Object)public static <T extends Comparable<? super T>> T median(T... items)
T - type of values processed by this methoditems - to compareNullPointerException - if items is nullIllegalArgumentException - if items is empty or contains null valuespublic static <T> T median(Comparator<T> comparator, T... items)
T - type of values processed by this methodcomparator - to use for comparisonsitems - to compareNullPointerException - if items or comparator is nullIllegalArgumentException - if items is empty or contains null valuespublic static <T> T mode(T... items)
T - type of values processed by this methoditems - to checknull if non-unique or no items suppliedpublic static <T> T clone(T obj)
Clone an object.
T - the type of the objectobj - the object to clone, null returns nullCloneable otherwise nullCloneFailedException - if the object is cloneable and the clone operation failspublic static <T> T cloneIfPossible(T obj)
Clone an object if possible.
This method is similar to clone(Object), but will return the provided
instance as the return value instead of null if the instance
is not cloneable. This is more convenient if the caller uses different
implementations (e.g. of a service) and some of the implementations do not allow concurrent
processing or have state. In such cases the implementation can simply provide a proper
clone implementation and the caller's code does not have to change.
T - the type of the objectobj - the object to clone, null returns nullCloneable otherwise the object itselfCloneFailedException - if the object is cloneable and the clone operation failspublic static boolean CONST(boolean v)
public final static boolean MAGIC_FLAG = ObjectUtils.CONST(true);
This way any jars that refer to this field do not
have to recompile themselves if the field's value
changes at some future date.v - the boolean value to returnpublic static byte CONST(byte v)
public final static byte MAGIC_BYTE = ObjectUtils.CONST((byte) 127);
This way any jars that refer to this field do not
have to recompile themselves if the field's value
changes at some future date.v - the byte value to returnpublic static byte CONST_BYTE(int v) throws IllegalArgumentException
public final static byte MAGIC_BYTE = ObjectUtils.CONST_BYTE(127);
This way any jars that refer to this field do not
have to recompile themselves if the field's value
changes at some future date.v - the byte literal (as an int) value to returnIllegalArgumentException - if the value passed to v
is larger than a byte, that is, smaller than -128 or
larger than 127.public static char CONST(char v)
public final static char MAGIC_CHAR = ObjectUtils.CONST('a');
This way any jars that refer to this field do not
have to recompile themselves if the field's value
changes at some future date.v - the char value to returnpublic static short CONST(short v)
public final static short MAGIC_SHORT = ObjectUtils.CONST((short) 123);
This way any jars that refer to this field do not
have to recompile themselves if the field's value
changes at some future date.v - the short value to returnpublic static short CONST_SHORT(int v) throws IllegalArgumentException
public final static short MAGIC_SHORT = ObjectUtils.CONST_SHORT(127);
This way any jars that refer to this field do not
have to recompile themselves if the field's value
changes at some future date.v - the short literal (as an int) value to returnIllegalArgumentException - if the value passed to v
is larger than a short, that is, smaller than -32768 or
larger than 32767.public static int CONST(int v)
public final static int MAGIC_INT = ObjectUtils.CONST(123);
This way any jars that refer to this field do not
have to recompile themselves if the field's value
changes at some future date.v - the int value to returnpublic static long CONST(long v)
public final static long MAGIC_LONG = ObjectUtils.CONST(123L);
This way any jars that refer to this field do not
have to recompile themselves if the field's value
changes at some future date.v - the long value to returnpublic static float CONST(float v)
public final static float MAGIC_FLOAT = ObjectUtils.CONST(1.0f);
This way any jars that refer to this field do not
have to recompile themselves if the field's value
changes at some future date.v - the float value to returnpublic static double CONST(double v)
public final static double MAGIC_DOUBLE = ObjectUtils.CONST(1.0);
This way any jars that refer to this field do not
have to recompile themselves if the field's value
changes at some future date.v - the double value to returnpublic static <T> T CONST(T v)
public final static String MAGIC_STRING = ObjectUtils.CONST("abc");
This way any jars that refer to this field do not
have to recompile themselves if the field's value
changes at some future date.T - the Object typev - the genericized Object value to return (typically a String).Copyright © 2001–2015 The Apache Software Foundation. All rights reserved.