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When do I need to rewrite equals ()?Equals () returns a true value only if an instance equals itself. In layman's words, the comparison at this point is whether the two references point to the same object in memory, or whether the instances are equal. When we use Equals () to compare two references to value objects, we
comparison reference is the same).Hashcode () is a local method, and its implementation is dependent on the local machine.2. The Java language requirements for Equals () are as follows, and these requirements must be followed:A symmetry: If X.equals (y) returns "true", then Y.equals (x) should also return "true".B reflectivity: x.equals (x) must return is "true"
) = true I = i2 = true I1.equals (I) = true I = i4 = true I4.equals (I) = true 3> hashcode and equals of the object1) to understand the role of hashcode, we can understand it in java. lang. Object. Every time a new JVM Object is
A Brief Introduction to the correct method for evaluating hashCode in Java and the value of hashcode This article focuses on the relevant content of the correct hashCode Evaluate Method in Java, as detailed below. The hash list has an optimization function to cache the
First, why should have hash algorithmThere are two types of collections in Java , one is list, and the other is set. The elements in the list are ordered and the elements can be duplicated. The set element is unordered, but the element is not repeatable. If you want to ensure that the elements are not duplicated, should the two elements be repeated according to what to judge? Use the Object.Equals method. However, if each additional element is checked
into the collection, how do you determine if the object already exists in the collection? Perhaps most people would have thought of calling the Equals method to make comparisons on a case by case basis. However, if there are already 10,000 or more data in the collection, if the Equals method is used to compare each other, efficiency must be a problem. At this point the function of the
Turn http://blog.csdn.net/fenglibing/article/details/8905007the role of hashcode in Java2013-05-09 13:54 64351 people read review (+) Collection report Classification:Java Utility Note (142)Copyright Notice: This article for Bo Master original article, without Bo Master permission not Reproduced.The following is an official document definition for hashcode:[plain]View PlainCopy The
Original May 09, 2013 13:54:53 147528 The following is an official document definition for hashcode:[Plain]View PlainCopy The Hashcode method returns the hash code value of the object. This method is supported to provide some advantages to the hash table, for example, the Hashtable provided by Java.util.Hashtable. The general agreement of Hashcod
The following is an official definition of hashcode document: The hashcode method returns the hash code value of this object. This method provides some advantages for the hash table, such as the hash table provided by Java. util. hashtable. The conventional hashcode protocol is that, when calling the
The following is an official document definition for hashcode:[Plain]View Plaincopy The Hashcode method returns the hash code value of the object. This method is supported to provide some advantages to the hash table, for example, the Hashtable provided by Java.util.Hashtable. The general agreement of Hashcode is: During
Java Basics (1) hashcode ()See an article about Hashcode (), written in a very detailed understanding, a sudden feeling of an epiphany, so specifically turned around. Original:http://blog.csdn.net/fenglibing/article/details/8905007Reference:http://www.importnew.com/11334.htmlThe following is an official document definition for hashcode:The
Introduction to the hashcode method in Java The hash table data structure is certainly not unfamiliar to most people, and hash tables are used in many places to improve the search efficiency. There is a method in the Object class of Java: public native int hashCode(); According to the declaration of this method, this m
Hash table This data structure presumably most people are not unfamiliar, and in many places will use hash tables to improve the search efficiency. There is a method in the object class in Java:public native int hashcode ();According to the declaration of this method, the method returns a numeric value of type int and is a local method, so no specific implementation is given in the object class.Why does the object class need such a method? What role d
On the Hashcode method in Java Hash table This data structure presumably most people are not unfamiliar, and in many places will use hash tables to improve the search efficiency. There is a method in the object class in Java: public native int hashcode (); Why does the object class need such a method? What role does it
Hash table This data structure presumably most people are not unfamiliar, and in many places will use hash tables to improve the search efficiency. There is a method in the object class in Java:public native int hashcode ();According to the declaration of this method, the method returns a numeric value of type int and is a local method, so no specific implementation is given in the object class.Why does the object class need such a method? What role d
First, to understand the role of hashcode, you must first know the collection in Java.In general, there are two types of collections (Collection) in Java, one is list, and the other is set. Do you know the difference between them? The elements within the set are ordered, the elements can be repeated, the latter elements are unordered, but the elements are not repeatable. So here is a more serious problem: t
A hash table This data structure must be familiar to most people, and in many places, hash tables are used to improve search efficiency. There is a method in the Java object class: According to the declaration of this method, the method returns a numeric value of type int and is a local method, so no specific implementation is given in the object class. Why does the object class need such a method? How does it work? Today we will discus
except 8 of the remainder is 1, then we put the class exists 1 this position, if the ID is 13, the remainder is 5, then we put the class at 5 this position.In this way, the remainder can be found directly by ID in addition to 8 when the class is looked up. 2. But if the two classes have the same hashcode what to do (we assume that the ID of the class above is no
The reason why we write hashcode, because usually we always hear it. But do you really know hashcode? Where will it be used? How should it be written?I believe reading this article, can let you see different hashcode.The purpose of using hashcode is to use one object to find another object. For data structures that use hashing, for example HashSet、HashMap、LinkedH
HashCode (); It is a local method, and its implementation is related to the local machine. Here we temporarily think that the physical location of the Object Storage is returned (actually not, it is easy to understand here ). When we add an element to a set, the set will first call the hashCode method, so that we can directly locate the location it stores. If there are no other elements, it will be saved di
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