CODEWITHSUNDEEP
javaoopobject
Flame of udun
Flame of udun

Reputation: 2237

When is a reference to the object class required?

What is the function of the class Object in java? All the "objects" of any user defined class have the same function as the aforementioned class .So why did the creators of java create this class? In which situations should one use the class 'Object'?

Upvotes: 0

Views: 107

Answers (4)

Mike Braun
Mike Braun

Reputation: 3769

What Java implements is sometimes called a "cosmic hierarchy". It means that all classes in Java share a common root.

This has merit by itself, for use in "generic" containers. Without templates or language supported generics these would be harder to implement.

It also provides some basic behaviour that all classes automatically share, like the toString method.

Having this common super class was back in 1996 seen as a bit of a novelty and cool thing, that helped Java get popular (although there were proponents for this cosmic hierarchy as well).

Upvotes: 1

lreeder
lreeder

Reputation: 12206

Object provides an interface with functionality that the Java language designers felt all Java objects should provide. You can use Object when you don't know the subtype of a class, and just want to treat it in a generic manner. This was especially important before the Java language had generics support.

There's an interesting post on programmers.stackexchange.com about why this choice was made for .NET, and those decisions most likely hold relevance for the Java language.

Upvotes: 1

chrylis -cautiouslyoptimistic-
chrylis -cautiouslyoptimistic-

Reputation: 77177

Pretty much the only time that Object is used raw is when it's used as a lock object (as in Object foo = new Object(); synchronized(foo){...}. The ability to use an object as the subject of a synchronized block is built in to Object, and there's no point to using anything more heavyweight there.

Upvotes: 2

pamphlet
pamphlet

Reputation: 2104

Since all classes in Java are obligated to derive (directly or indirectly) from Object, it allows for a default implementation for a number of behaviours that are needed or useful for all objects (e.g. conversion to a string, or a hash generation function).

Furthermore, having all objects in the system with a common lineage allows one to work with objects in a general sense. This is very useful for developing all sorts of general applications and utilities. For example, you can build a general purpose cache utility that works with any possible object, without requiring users to implement a special interface.

Upvotes: 3

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