blocks|key|677302|text|不一定。来自文档+(重点雷)：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|677303|根据合理的实际情况，类对象定义的hashCode方法确实返回不同对象的不同整数。(这通常是通过将对象的内部地址转换为整数来实现的，但是JavaTM编程语言并不需要这种实现技术。)|blockquote|style|BOLD|677304|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/6/docs/api/java/lang/Object.html#hashCode%2528%2529^0|6|2|0|0|1O|H|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@$A|V|B|W|G|H]]|9|@]|C|$]]|$1|I|3|-4|5|6|7|X|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Not necessarily. From the <a href="http://docs.oracle.com/javase/6/docs/api/java/lang/Object.html#hashCode%28%29" rel="noreferrer">documentation</a> (emphasis mine):

<blockquote>
 As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)
</blockquote>

blocks|key|1370084|text|始终可以通过查看JDK附带的源代码来进行检查。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1370085|我的java.lang.Object将hashCode显示为本机方法。这里是javadocs。|offset|length|style|CODE|1370086|/**
+*+Returns+a+hash+code+value+for+the+object.+This+method+is+
+*+supported+for+the+benefit+of+hashtables+such+as+those+provided+by+
+*+<code>java.util.Hashtable</code>.+
+*+
+*+The+general+contract+of+<code>hashCode</code>+is:+
+*+<ul>
+*+<li>Whenever+it+is+invoked+on+the+same+object+more+than+once+during+
+*+++++an+execution+of+a+Java+application,+the+<tt>hashCode</tt>+method+
+*+++++must+consistently+return+the+same+integer,+provided+no+information+
+*+++++used+in+<tt>equals</tt>+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.+
+*+<li>If+two+objects+are+equal+according+to+the+<tt>equals(Object)</tt>
+*+++++method,+then+calling+the+<code>hashCode</code>+method+on+each+of+
+*+++++the+two+objects+must+produce+the+same+integer+result.+
+*+<li>It+is+not+required+that+if+two+objects+are+unequal+
+*+++++according+to+the+{@link+java.lang.Object#equals(java.lang.Object)}+
+*+++++method,+then+calling+the+<tt>hashCode</tt>+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+hashtables.
+*+</ul>
+*+
+*+As+much+as+is+reasonably+practical,+the+hashCode+method+defined+by+
+*+class+<tt>Object</tt>+does+return+distinct+integers+for+distinct+
+*+objects.+(This+is+typically+implemented+by+converting+the+internal+
+*+address+of+the+object+into+an+integer,+but+this+implementation+
+*+technique+is+not+required+by+the+
+*+Java<font+size="-2">TM+programming+language.)
+*
+*+@return++a+hash+code+value+for+this+object.
+*+@see+++++java.lang.Object#equals(java.lang.Object)
+*+@see+++++java.util.Hashtable
+*/
public+native+int+hashCode();|code-block|syntax|javascript|1370087|entityMap^0|0|2|G|J|8|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@$D|Q|E|R|F|G]|$D|S|E|T|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|U|8|@]|9|@]|A|$K|L]]|$1|M|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|N|$]]

You can always check by looking at the source that ships with your JDK.

My <code>java.lang.Object</code> shows <code>hashCode</code> as a native method. Here are the javadocs.

<pre><code>/**
 * Returns a hash code value for the object. This method is 
 * supported for the benefit of hashtables such as those provided by 
 * &lt;code&gt;java.util.Hashtable&lt;/code&gt;. 
 * &lt;p&gt;
 * The general contract of &lt;code&gt;hashCode&lt;/code&gt; is: 
 * &lt;ul&gt;
 * &lt;li&gt;Whenever it is invoked on the same object more than once during 
 * an execution of a Java application, the &lt;tt&gt;hashCode&lt;/tt&gt; method 
 * must consistently return the same integer, provided no information 
 * used in &lt;tt&gt;equals&lt;/tt&gt; 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. 
 * &lt;li&gt;If two objects are equal according to the &lt;tt&gt;equals(Object)&lt;/tt&gt;
 * method, then calling the &lt;code&gt;hashCode&lt;/code&gt; method on each of 
 * the two objects must produce the same integer result. 
 * &lt;li&gt;It is &lt;em&gt;not&lt;/em&gt; required that if two objects are unequal 
 * according to the {@link java.lang.Object#equals(java.lang.Object)} 
 * method, then calling the &lt;tt&gt;hashCode&lt;/tt&gt; 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 hashtables.
 * &lt;/ul&gt;
 * &lt;p&gt;
 * As much as is reasonably practical, the hashCode method defined by 
 * class &lt;tt&gt;Object&lt;/tt&gt; does return distinct integers for distinct 
 * objects. (This is typically implemented by converting the internal 
 * address of the object into an integer, but this implementation 
 * technique is not required by the 
 * Java&lt;font size="-2"&gt;&lt;sup&gt;TM&lt;/sup&gt;&lt;/font&gt; programming language.)
 *
 * @return a hash code value for this object.
 * @see java.lang.Object#equals(java.lang.Object)
 * @see java.util.Hashtable
 */
public native int hashCode();
</code></pre>

blocks|key|675355|text|正如文档+on+Object.hashCode()所述，|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|675356|根据合理的实际情况，类对象定义的hashCode方法确实返回不同对象的不同整数。(这通常是通过将对象的内部地址转换为整数来实现的，但是JavaTM编程语言并不需要这种实现技术。)|blockquote|675357|因此，Java语言不需要对象类的哈希代码返回对象的内存地址，因此不应该依赖于此。|675358|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/6/docs/api/java/lang/Object.html#hashCode%2528%2529^0|2|2|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$]]|$1|G|3|H|5|6|7|V|8|@]|9|@]|C|$]]|$1|I|3|-4|5|6|7|W|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

As the <a href="http://docs.oracle.com/javase/6/docs/api/java/lang/Object.html#hashCode%28%29" rel="nofollow">documentation</a> on Object.hashCode() states,

<blockquote>
 As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.) 
</blockquote>

So, the Java language has no requirement for the hashcode of the Object class to return the memory address of the object and therefore you should not rely on this.

blocks|key|890672|text|不，HashCode()函数返回一个整数。如果您没有为对象定义HashCode()函数，Java可以将对象的内存地址转换为整数并返回该整数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|890673|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

No, the HashCode() function returns an integer. If you have not defined a HashCode() function for your object, Java MAY transcode the memory address of the object to an integer and return that.

<blockquote>
 Possible Duplicate: 
 <a href="https://stackoverflow.com/questions/2237720/what-is-an-objects-hashcode">what is an objects hashcode</a> 
 <a href="https://stackoverflow.com/questions/4930781/how-do-hashcode-and-identityhashcode-work-at-the-back-end">How do hashCode() and identityHashCode() work at the back end?</a> 
</blockquote>



I'm not talking about String class or any other class where the hashcode is overridden. Say if I just create a new object of the <code>Object</code> class, then will the <code>hashcode()</code> or to be true in any case, <code>identityHashCode(Object x)</code> return the memory address of that object?

Does hashcode return the memory address?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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可能重复：我说的不是字符串类，也不是重写哈希代码的任何其他类。假设我刚刚为Object类创建了一个新对象，那么hashcode()或者在任何情况下都是真，identityHashCode(Object x)会返回该对象的内存地址吗？

问哈希码返回内存地址吗？
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问哈希码返回内存地址吗？
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