Java SE 7, Objects class, http://download.java.net/jdk7/docs/api/java/util/Objects.html Objects 類別提供全為 Static 方法,
java.util
|
修飾子與型別 | 方法描述與描述 | |
---|---|---|
static
|
compare(T a,
T b,
Comparator<? super T> c)
Returns 0 if the arguments are identical and c.compare(a,
b) otherwise. |
|
static boolean |
deepEquals(Object a,
Object b)
Returns true if the arguments are deeply equal to
each other
and false otherwise. |
|
static boolean |
equals(Object a,
Object b)
Returns true if the arguments are equal to each
other
and false otherwise. |
|
static int |
hash(Object... values)
Generates a hash code for a sequence of input values. |
|
static int |
hashCode(Object o)
Returns the hash code of a non- null argument and 0
for
a null argument. |
|
static
|
nonNull(T obj)
Checks that the specified object reference is not null . |
|
static
|
nonNull(T obj,
String message)
Checks that the specified object reference is not null
and
throws a customized NullPointerException if it
is. |
|
static String |
toString(Object o)
Returns the result of calling toString for a non-null
argument and "null" for a null argument. |
|
static String |
toString(Object o,
String nullDefault)
Returns the result of calling toString on the
first
argument if the first argument is not null and returns
the second argument otherwise. |
一個空安全(null-safe)的equals(arg1, arg2)方法,如果兩個參數都為null返回true,如果只有一個為 null 返回 false,其他情況則調用arg1.equals(arg2)
一套針對所有原生類型(int、long等)的compareTo(arg1, arg2)方法
toString(arg),通過反射將對象中的所有屬性都寫到返回的輸出字符串中
對clone()方法的一個輔助實現
一個空安全的hashCode()實現,對於值為null的對象該方法返回0。
References
- http://www.baptiste-wicht.com/2010/04/java-7-the-new-java-util-objects-class/
- http://63.246.7.136/cn/news/2009/09/jdk7-java-utils-object