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hashCode() method

 
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hi
Can anybody tell me when hashCode() method gets invoked and
When do we need to override it?

And what value is returned for custom object in SOP, if we dont overrride
toString() method in that particular class. Its something like name of Object followed by a number. What does tht mean.
 
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"Shaily S,"

Welcome to JavaRanch!

First, please revise your display name to meet the JavaRanch Naming Policy. To maintain the friendly atmosphere here at the ranch, we like folks to use real (or at least real-looking) names, with a first and last name. The first name can be an initial, but the last name cannont. You can edit your display name here.

In general, hashCode() is called whenever an object is added to or retrieved from a container using hashing (for example, a HashSet or HashMap). So if instances of your class have the potential to be stored in such a container, you should override hashCode (and equals).

hashcode() is also invoked in the default bahavior of toString(), which is described in the API documentation for java.lang.Object...

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character '@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

getClass().getName() + '@' + Integer.toHexString(hashCode())

 
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