PorterDuffColorFilter

PorterDuffColorFilter

PorterDuffColorFilter (int color, 
                PorterDuff.Mode mode)

创建一个使用指定颜色和Porter-Duff模式的颜色过滤器。

equals

boolean equals (Object object)

指示其他某个对象是否“等于”这一个。

equals方法在非空对象引用上实现等价关系：

• It is reflexive: for any non-null reference value x, x.equals(x) should return true.
• It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
• It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x, x.equals(null) should return false.

类Object的equals方法实现了对象上最可能的等价关系; 也就是说，对于任何非空引用值x和y ，此方法返回true当且仅当x和y指代相同的对象（ x == y具有值true ）。

请注意，无论何时覆盖此方法，通常都必须覆盖 hashCode方法，以便维护 hashCode方法的一般合同，该方法声明相等对象必须具有相同的散列代码。

hashCode

int hashCode ()

返回对象的哈希码值。 此方法支持哈希表的好处，例如由HashMap提供的哈希表。

hashCode的总合同是：

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

尽可能合理实用，由类Object定义的hashCode方法确实为不同的对象返回不同的整数。 （这通常通过将对象的内部地址转换为整数来实现，但Java ^TM编程语言不需要此实现技术。）