hashCode和equals的关系中,hashCode不相等,equals是肯定不相等。

hashCode和equals的关系中,hashCode不相等,equals是肯定不相等。


参考答案和解析
equals()不相等的两个对象,却并不能证明他们的hashcode()不相等。;hashcode()相等,equals()可能相等,也可能不等

相关考题:

WhatistheappropriatedefinitionofthehashCodemethodinclassPerson?() A.returnsuper.hashCode();B.returnname.hashCode()+age*7;C.returnname.hashCode()+comment.hashCode()/2;D.returnname.hashCode()+comment.hashCode()/2-age*3;

classSock{Stringsize;Stringcolor;publicbooleanequals(Objecto){Socks=(Sock)o;returncolor.equals(s.color);}//insertcodehere}哪两个满足hashCode的约定?() A.publicinthashCode(){return343;}B.publicinthashCode(){returnsize.hashCode();}C.publicinthashCode(){returncolor.hashCode();}D.publicinthashCode(){return(int)(Math.random()*1000);

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publicclassPerson{privateStringname,comment;privateintage;publicPerson(Stringn,inta,Stringc){name=n;age=a;comment=c;}publicbooleanequals(Objecto){if(!(oinstanceofPerson))returnfalse;Personp=(Person)o;returnage==p.agename.equals(p.name);}}WhatistheappropriatedefinitionofthehashCodemethodinclassPerson?()A.returnsuper.hashCode();B.returnname.hashCode()+age*7;C.returnname.hashCode()+comment.hashCode()/2;D.returnname.hashCode()+comment.hashCode()/2-age*3;

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YouwanttouseteCoherenceJavaAPIstodirectlycachedPOJOs.Considerthissnippetofcode:NamedCachecache-CacheFactory.getCache(mycache);cache.put(newInteger(I)fhello);cache.put(T,hi);cache.put(newLong(II),hey);Thiscodeinsertsthreeobjectsintothecache.Why?()A.hashCode()andequals()methodforeachobjecttypeisdifferentsoadifferentkeyisusedB.eachobjectvaluestringisdifferentsoadifferentvalueisinsertedoneachputC.equals()andcompare()methodisdifferentforeachputD.POFneedtobeimplementedforthistoworkproperly

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Which two statements are true about the hashCode method?()A、 The hashCode method for a given class can be used to test for object equality and object inequality for that class.B、 The hashCode method is used by the java.util.SortedSet collection class to order theelements within that set.C、 The hashCode method for a given class can be used to test for object inequality, but NOT object equality, for that class.D、 The only important characteristic of the values returned by a hashCode method is that the distribution of values must follow a Gaussian distribution.E、 The hashCode method is used by the java.util.HashSet collection class to group the elements within that set into hash buckets for swift retrieval.

程序员正在进行一个项目,必须实现equals方法与所给的hashCode方法协调运行:()  public int hashCode() {   return (size.hashCode() + color.hashCode()) * 17;   }   哪一个equals方法支持此目标?()  A、 无法确定B、 public boolean equals(Object o) {  Sock s = (Sock) o;return size.equals(s.size);  } C、 public boolean equals(Object o) {  Sock s = (Sock) o;return color.equals(s.color); }D、 public boolean equals(Object o) {  Sock s = (Sock) o;return size.equals(s.size) color.equals(s.color); }

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多选题Which two statements are true regarding the return values of property written hashCode and equals methods from two instances of the same class?()AIf the hashCode values are different, the objects might be equal.BIf the hashCode values are the same, the object must be equal.CIf the hashCode values are the same, the objects might be equal.DIf the hashCode values are different, the objects must be unequal.

单选题如下关于Java编码描述不正确的是()A除了构建器外,不要使用和类名相同的方法名B使用equals()比较两个类的值是否相同C不要使用嵌套赋值,即在一个表达式中使用多个=D重载equals()方法时,不必要重载hashCode()方法

单选题You want to use te Coherence Java APIs to directly cached POJOs. Consider this snippet of code: NamedCache cache - CacheFactory.getCache("mycache");  cache.put(new Integer(I)f "hello"); cache.put(T,"hi");  cache.put(new Long(II),"hey");  This code inserts three objects into the cache.  Why ?()A hashCode() and equals() method for each object type is different so a different key is usedB each object value string is different so a different value is inserted on each putC equals() and compare() method is different for each putD POF need to be implemented for this to work properly

问答题两个对像值相同(x.equals(y)==true),但却可有不同的hashcode,这句话对不对?

多选题Which two statements are true about the hashCode method?()AThe hashCode method for a given class can be used to test for object equality and object inequality for that class.BThe hashCode method is used by the java.util.SortedSet collection class to order theelements within that set.CThe hashCode method for a given class can be used to test for object inequality, but NOT object equality, for that class.DThe only important characteristic of the values returned by a hashCode method is that the distribution of values must follow a Gaussian distribution.EThe hashCode method is used by the java.util.HashSet collection class to group the elements within that set into hash buckets for swift retrieval.

单选题程序员正在进行一个项目,必须实现equals方法与所给的hashCode方法协调运行:  public int hashCode() {    return (size.hashCode() + color.hashCode()) * 17;    }    哪一个equals方法支持此目标?()A 无法确定B public boolean equals(Object o) {  Sock s = (Sock) o; return size.equals(s.size);}C public boolean equals(Object o) {  Sock s = (Sock) o; return color.equals(s.color);}D public boolean equals(Object o) {  Sock s = (Sock) o; return size.equals(s.size) color.equals(s.color);  }