Why does every object in Java implicitly extend java.lang.Object class?

Question

I have been programming in Java for quite some time, but when I tried to explain what an java.lang.Object class is to a friend, I could not come up with more th

Answer 1

I would say Design. Common/Mandatory methods which every Object should support written there and extending that class as a language specification.

You find the reasons here in Official Docs.

If we are saying this is an Object ,They must have the common methods, Which defined/decided by API.

Imagine the below methods for every class on your Own.

protected Object clone() throws CloneNotSupportedException
      Creates and returns a copy of this object.


public boolean equals(Object obj)
      Indicates whether some other object is "equal to" this one.


protected void finalize() throws Throwable
      Called by the garbage collector on an object when garbage
      collection determines that there are no more references to the object


public final Class getClass()
      Returns the runtime class of an object.


public int hashCode()
      Returns a hash code value for the object.


public String toString()
      Returns a string representation of the object.

The notify, notifyAll, and wait methods of Object all play a part in synchronizing the activities of independently running threads in a program:

public final void notify()
public final void notifyAll()
public final void wait()
public final void wait(long timeout)
public final void wait(long timeout, int nanos) 

So to reduce the pain, created a common and standard API.