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In the next several videos we're going to
apply what we've learned in the class to

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analysis of various features of Java. This
will give us a chance to both look at a

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real programming language and how it's
designed and been done. And also to talk

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about some features that art in Cool that
we haven't been able to cover thus far in

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the course. For the perspective of this
class, Java is a kind of Cool on steroids.

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It's Cool plus more features, many more
features. At, at their core Java and Cool

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are very similar. Java and Cool are both
typed object oriented garbage collected

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languages. They were both designed in the
early 1990s and so they share a common

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culture there with the ideas that were
current at that time. So in this video,

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I'm just going to give a little bit of
history of Java so that will be the focus

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really of this rather short video. And
then in the subsequent videos, we'll talk

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about all the features or some of the
features of Java that are not in Cool. And

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we'll use the ideas of course that we've
been discussing all along through the

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class, to explain a little bit about those
ideas. But I think these are all important

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language constructs that are unfortunately
were too time consuming or too complicated

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to add to the course project. So I think
it's useful to use a language like

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[inaudible] to illustrate how these ideas
work and what some of the issues are. So

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Java began as a project called Oak at SUN
Microsystems and it was originally

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targeted at set top devices. And so what
was a set top device? This was a little

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box that was gonna sit on top of your TV
So you had your TV screen, and then there

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was going to be this little thing up here
that was going to sit on top of the TV

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that was going to control all your cable
programming. So this would essentially

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would connect to some kind of network and
it would help you to do, you know to make

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your TV more interactive. Okay, so this
was back in the days before every TV was

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really a computer by itself. The initial
develo pment of, of Oak took several

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years. I believe the project ran from
about 91 to 94 and what happened, at least

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as I understand it, is that this set top
device market just never took off. So this

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never became a popular never, never became
a popular idea with consumers and, and so

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there really was a kind of limited up side
or a limited potential for, for Oak at the

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time. And then something happened, the
Internet happened. So also in the early

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90s the Internet revolution was really
gathering steam. Everybody was getting on

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the Internet and it became obvious
sometime 93, 94 that there was going to be

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a need for programming languages that
really addressed these specific issues on

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the Internet. And in particular people
were very concerned about security. And,

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they didn't want to be downloading lots of
binaries that were programs written in C

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and passing those around on the Internet
because it was just really no guarantee

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that those programs would work as intended
and not crash your machine. So you know,

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they needed to be able to share code over
the Internet from other people that you

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didn't necessarily trust completely meant
that we needed safer languages than

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languages like C and C++ and so there was
an opportunity there for a, a new language

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and there were several candidates
actually. Besides Java, Tickle and Python

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were very serious candidates to become the
Internet programming language eventually

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the backing of SUN Microsystems, the
backing of SUN gave to Java helped it to

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really gain a very, very strong presence
on the Internet. But you know, the point

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of this story is that every new language
needs a killer app. Every programming

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language rides into the world on the back
of some application. So there has to be

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some kind of new application that people
want to write that the existing languages

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don't serve very well and that provides
the opportunity and therefore makes it

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worthwhile for people to learn a new
programming language. And so the fact that

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Ja va was a very safe language, it had the
garbage collection. It had the type system

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that made it well suited at the time to
the, the needs of the emerging needs of

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internet programming. And it became very
popular I think primarily because of that

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reason. And if you if you recall there was
a lecture or a video early on, on the

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economy of programming languages. And I
would recommend actually that if you

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haven't watched that one, then you go back
and take a look because there I discuss

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some of these ideas about how languages
are adopted in more detail. So Java also

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came into existence in a particular
technical environment and it's very

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common. In fact, it's normal for new
programming languages to borrow heavily

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from their predecessors and new languages
are often mostly recombinations of ideas

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from previous languages in a new design
perhaps with some innovations thrown in.

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And the particular influences on Java.
Again this is at least so far as I

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understand it so the type system in Java,
or its, its commitment to types probably

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is traceable to Modula-3 and the ideas
there where people try to build a sort of

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programming language that would scale in a
realistic way to large systems but also be

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strongly typed. The object orientation of
Java is traceable to languages like

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Objective C and C++ and, and also Eiffel
which also had the idea of interfaces

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which is a prominent feature in Java. And
finally Java is quite a dynamic language

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meaning that there many things that are
not done staticly. They're done

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dynamically so features like reflection
would be one example of that. And there

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are actually quite a few other features
and there is some history there. There's

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some shared culture there with Lisp. This
was a or is a functional family language

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but is also a very, very dynamic language.
As I said at the beginning this video is

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just an introduction and overview and in
the next few videos, we'll be looking at

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specific features of Java and how they
work. And that will includes things like

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exceptions, interfaces, and threads. As
well as a bunch of other features that

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we'll discuss at least, briefly. One thing
to realize is that Java is a big language.

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It is not simple. The language manual for
Java runs to hundreds and hundreds of

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pages. It has lots of features. And
perhaps more importantly, lots of feature

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interactions. So. The hard part of
designing a language of course is getting

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all the feature interactions right. All
the combinations of the features and, you

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know making sure there are no surprising
interactions between them.