hashcode and equals in java

and double encapsulation classes are also suitable for this principle. Of course, it has not been rewritten.Class. This principle is also observed after the equals () and hashcode () Methods of the object class are inherited. 4. When talking about hashcode () and equals (), we can't help but talk about the usage of ha

Equals () method.Look at the code:Java.lang.String public final class String implements Java.io.Serializable, Comparable　　It can be seen that this is a rewrite of equals (), and here is a comparison of whether two strings are the same, OK, but one thing to remember is that if you rewrite equals () it is necessary to rewrite

. Wait, these classes are all overriding the Equals () method, thus making a comparison of the content. Of course, the basic type is the comparison of values, this is nothing to say.We should also note that the Java language requirements for Equals () are as follows, and these requirements must be followed:• Symmetry: If X.equals (y) returns "true", then Y.equals

Summary:This paper mainly records my hashcode and equals two knowledge points of the learning Process.From the time of students to learn java, know hashcode and equals the two methods, the use of the Equals method is particularly

"; x.equals (and x objects of different types) will always return "false" 4. Summarytherefore, for the Equals method: It is intended to compare the content of two objects with the same When necessary, we need to rewrite this method to avoid breaking the original intention and to follow the above principles Iv. Methods of Hashcode1, the source of HashcodeThe Hashcode method is the ins

Java --- hashCode () and equals (),1. hashCode () and equals () APIs HashCode() AndEquals() All come from the god classObject,All classes have these two methods: special timing and re-writing. They are used for comparison in the s

Tips"Effective Java, third Edition" an English version has been published, the second edition of this book presumably many people have read, known as one of the four major Java books, but the second edition of 2009 published, to now nearly 8 years, but with Java 6, 7, 8, and even 9 of the release, the Java language has

information used in the Equals comparison on the object has not been modified.X,x.equals (NULL) should return FALSE for any non-null reference value.The Equals method of the object class implements the most differentiated equality relationship on the object, that is, for any non-null reference value x and Y, this method returns True if and only if X and Y refer to the same object (x = = Y has a value of tr

The Equals method and the Hashcode method in Java are in object, so each object has these two methods, sometimes we need to implement the specific requirements, we may have to rewrite the two methods, today we will introduce some of the effects of these two methods. The Equals () and

The Hashcode method returns the hash code value of the object.The Hashcode () method can be used to improve the efficiency of the search in the map, map will be based on different hashcode () in different locations, map in the search for an object by Hashcode () to find the corresponding position, and then according to

.(3) Default.= = Compares the address of the object in the JVM by default.　　hashcode Default returns the storage address of the object in the JVM.Equal compare objects, the default is to compare objects in the JVM address, with = =Reference:http://docs.oracle.com/javase/7/docs/api/java = =, Equals (), hashcode () Sourc

Note hashcode only when hashtable, hashmap, hashset, and linkedhashmap are used. hashcode is useless in other places. (This is not necessarily true) Whether two objects are equal requires that hashcode () be equal. Is the following statement true? In a Java set, the rule for determining whether two objects are equal is

field in the object. Returns true if all of these tests are successful, otherwise false.5. After writing completes the Equals method, check for symmetry, transitivity, and consistency.3, HashcodeThe Hashcode () method returns a numeric value, as can be seen from the name of the method, and its purpose is to generate a hash code. The main purpose of hash code is to hash the object as a key input, it is easy

Equals, =, and hashcode in javaI. = explanation 1. simple background everything in Java is an object. When running a program, the storage location of each object has the following options: 1) Register: the fastest speed, the smallest capacity, in Java, the memory is completely transparent-it cannot be controlled or rec

First of all, to understand the role of hashcode, you must first know the collection in Java. In general, the set in Java (Collection) has two classes, one is list, and the other is set. The elements in the former set are ordered, the elements can be duplicated, the latter elements are unordered, but the elements cannot be duplicated. So here is a more serious

directly on the source!public native int hashcode ();/*** Returns a hash code value for the object. This method is* Supported for the benefit of hashes tables such as those provided by* {@link Java.util.HashMap}.* * The general contract of {@code hashcode} are:* * * An execution of a Java application, the {@code Hashcode