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How this print() method works?

Debapriya Mukherjee
Greenhorn

Joined: Mar 07, 2012
Posts: 4
When I am Trying to Print an Object
Suppose,

It gives me
A@19821f
This seems to be a output of toString() method.
How this internal call happening?
I tried seeing the class hierarchy but getting confused?

Regards,
Deb
Jesper de Jong
Java Cowboy
Saloon Keeper

Joined: Aug 16, 2005
Posts: 14420
    
  23

This is how you find out:

- Look at the API documentation of class java.lang.System
- You see that it has a static member variable called "out", which is a java.io.PrintStream
- Look at the API documentation of class java.io.PrintStream
- You see that it has several overloaded versions of the print(...) method
- For your A object, it uses the print(Object) version
- Look at the API documentation for that method; it says:
API documentation wrote:Prints an object. The string produced by the String.valueOf(Object) method is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

So now you know that it calls String.valueOf(...) with your object as the argument. The API documentation of String.valueOf(...) says:
API documentation wrote:Returns:
if the argument is null, then a string equal to "null"; otherwise, the value of obj.toString() is returned.

In other words, this calls toString() on your object.

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Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 40027
    
  28
Read about toString() here.
 
It is sorta covered in the JavaRanch Style Guide.
 
subject: How this print() method works?