Is Java 100% object oriented? [closed]

Answer 1

"Why java doesn't design primitive data types as object way ?"

At Sun developer days, quite a few years ago I remember James Gosling answering this. He said that they'd liked to have totally abstracted away from primitives - to leave only standard objects, but then ran out of time and decided to ship with what they had. Very sad.

Answer 2

So can we consider java as 100% object oriented language?

No.

Another question : Why java doesn't design primitive data types as object way?

Mainly for performance reasons, possibly also to be more familiar to people coming from C++.

Answer 3

To get to true 100% OO think Smalltalk for instance, where everything is an object, including the compiler itself, and even if statements: ifTrue: is a message sent to a Boolean with a block of code parameter.

Answer 4

No, because it has data types that are not objects (such as int and byte). I believe Smalltalk is truly object-oriented but I have only a little experience with that language (about two months worth some five years ago).

I've also heard claims from the Ruby crowd but I have zero experience with that language.

This is, of course, using the definition of "truly OO" meaning it only has objects and no other types. Others may not agree with this definition.

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It appears, after a little research into Python (I had no idea about the name/object distinction despite having coded in it for a year or so - more fool me, I guess), that it may indeed be truly OO.

The following code works fine:

#!/usr/bin/python
i = 7
print id(i)
print type(i)
print i.__str__()

outputting:

6701648
<type 'int'>
7

so even the base integers are objects here.

Answer 5

Java, for the reason you mentioned, having primitives, doesn't make it a purely object-oriented programming language. However, the enforcement of having every program be a class makes it very oriented toward object-oriented programming.

Ruby, as you mentioned, and happened to be the first language that came to my mind as well, is a language that does not have primitives, and all values are objects. This certainly does make it more object-oriented than Java. On the other hand, to my knowledge, there is no requirement that a piece of code must be associated with a class, as is the case with Java.

That said, Java does have objects that wrap around the primitives such as Integer, Boolean, Character and such. The reason for having primitives is probably the reason given in Peter's answer -- back when Java was introduced in the mid-90's, memory on systems were mostly in the double-digit megabytes, so having each and every value be an object was large overhead.

(Large, of course is relative. I can't remember the exact numbers, but an object overhead was around 50-100 bytes of memory. Definitely more than the minimum of several bytes required for primitive values)

Today, with many desktops with multiple gigabytes of memory, the overhead of objects are less of an issue.

Answer 6

I'd say that full-OO languages are those which have their elements (classes, methods) accessible as objects to work with.

From this POV, Java is not fully OOP language, and JavaScript is (no matter it has primitives).