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Let's not look at the most fundamental class in Java because the object plus object glass is considered

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as the mother of all.

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And by that we mean that it is the superclass or her writing that is every class directly or indirectly

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and implicitly extends the Object class.

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For example we know that the user class is the top most class in our inheritance tree.

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So use that class directly and also implicitly extends the Object class.

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Who are the staff class also extends object but it does that in an indirect way.

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The other use a class since object class is a fundamental class.

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We know that it should be in the OR doglike package and there are two reasons for having the Object

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class.

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First one is that it acts as a polymorphic.

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That is you can assign any Jawa object to a variable whose reference type is Object class Unadilla job

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designers who create classes with methods that would pick any type that never existed when the first

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produced Garces.

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Second reason is it I think several code methods that are inherited by every class since the object

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class is the most super class on some of these methods can be used directly or can be overridden while

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others are Margret's whiner which means that they cannot be overridden.

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Now let's look at some of the most frequently used methods in the Object class.

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First one is the string method and as a name so just ignore it and say string representation of the

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object.

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And by default it includes the class name on some weird number as we can see here.

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In the case of stuff class let me just show this in the code.

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OK here we are creating a staff instance and we're simply printing out stuff got to string so we are

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invoking the string method on the staff reference so then I ran it.

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It just bends the staff class name followed by this weird number.

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So let's just go back.

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I come in from Effective Java.

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Actually it recommends to always override that boosting matter.

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And the reason is it is very useful for debugging and boosting is automatically in-road when the object

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reference is passed to the system dot dot Pentlands me.

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That is you don't have to invoke the string method explicitly.

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The printed matter does it automatically.

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The item also recommends that this mother children and all of the interesting information contained

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in the object.

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Let me also show this where the staff object in our class me just common default.

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Let me just uncommon this display use that info which was used in one of the previous day.

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So it's just going to the user class and the User class I'm HAVERTON this goosestepping matter.

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Just don't worry about this and not in it's quality and notation under Chancellery want.

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So the posting that there simply prints the data the attributes.

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So this whole piece of code was previously inside that display user informatic.

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So we are right we have it and disgusting method and this glue string method actually what right the

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string method in the superclass in the object class which is the superclass of user and display in the

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display use informatively or simply passing this object.

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And then we pass this the print Ellenwood automatically invoke the string method it wanted this dark

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blue string and at that instance this method would be invoked and this distinguished get printed.

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So we had this entire string inside display use info earlier.

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Now we are we have changed the implementation so that it would involve the two string matter.

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So let me just go ahead and run this as you can see it is amending the user info on its printing border

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attributes in the class.

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Next is a hash code matter.

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Undertreatment something called hash quote off an object which is basically the objects memory address

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and hexadecimal one.

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So two object differences pointing to the same object will have the same high score.

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And as you can see here the staff object is being referenced by two object references on both of them

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have identical hash codes and this method is supported for the benefit of hash tables which we will

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discuss in the collections framework chapter.

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Let's look at this method in code.

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So here we have the staff instance and we are simply printing the hash code and then we are creating

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a new area be able call staff.

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And we are assigning the same reference to it.

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So this way both of them refer to the same object.

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And when we opened the hash code for staff too it should be same as staff as a hash court for stuff

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.

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So let me run this.

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And as you can see both of them have the same high score.

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Next is equal to murder.

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And it compares two objects for equanimity and accrue if they are equal.

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So it compares the object on which the matter is invoked to the object that just passed us argument

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and by default this method uses the equality operator.

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You may recall the equality operator when applied on object references would return accrue only if both

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the object or Francis refer to the same object.

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But sometimes two different objects may be logical equaling that is and how identical contents.

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But they're still two different objects.

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Like in the example shown here.

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Here we have two different user objects which are initialized at the same ID and name.

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So they are logically equal and on Indicus up just like Haast tables you would want to create such kind

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of objects as equal.

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In that case you would have to override the equals method thereby overwriting its default behavior of

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using the equality operator.

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In this example you could add an equals method in the User class as shown here here only ID field is

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used as typically ID feels uniquely identify objects.

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Note is that the user parameter has to be Doncaster KREM object to use a class in order to use the get

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ID method as obviously Object class will not have this method.

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Next is the get class metric and it is basically a final method.

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And they did and something called a class object which encapsulates all the Mattei information about

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the class that is a class off the object on which this method is in work and meta information would

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include details like the class name superclass name method names and so on.

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And we will discuss it in more detail when we get to the GBM in the next chapter.

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Next to the clone method and it simply returns a copy of this object that is a clone of this object

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.

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And this matter is a protected matter and it must be overridden if we want to use its functionality

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.

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But let's not worry about it for now as we will look at it soon.

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When discussing a concept called interfaces so that's about the object last.

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There are a few other interesting methods but they're related to threads and will be discussed when

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we get to concurrency.

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Thank you