Download interpreted language

INTRODUCTION
TO
PROGRAMMING
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ICS 3U
WHAT IS A PROGRAM?
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A program is a set of instructions that makes the
computer do something.
There are two ways to supply a program to a
computer:
1) Buy a program written by somebody else (Future
Shop, Google Play Store, etc.).
2) Write the program yourself!
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HISTORY OF PROGRAMMING
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Computer circuits are in one of two binary states:
on when a signal is present
or
off when there is no signal present.
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Accordingly, computer programs are represented
in binary (1’s and 0’s) at the lowest level.
Called machine code, these strings of 1’s and 0’s
are long and difficult to understand! Not only are
they difficult to read, but they’re just as tough to
write!
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ASSEMBLY LANGUAGES
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As microprocessor development continued in the
1950s, symbolic machine languages called
assembly languages came into the scene.
Assembly languages allow the programmer to use
symbolic commands rather than cryptic binary to
accomplish tasks.
A program called the assembler translates the
source program (written in assembly) into an
object program (encoded in binary) which can
then be executed by your computer.
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HIGH-LEVEL LANGUAGES
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Problem: Assembly languages are designed to
work on certain microprocessors. A program
written on one machine will not necessarily work
on another.
A high-level programming language provides
easy-to-use shortcut commands to the
programmer with minimal drawbacks.
High-level source code needs to be compiled into
machine code before execution. The program that
does this translation is called a compiler. Highlevel languages can be compiled to run on the
most common types of microprocessor.
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EXAMPLE PROGRAM
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INTERPRETED LANGUAGES
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Problem: If I want my software to run on both
Windows and Mac, I have to program and
compile for two separate platforms!
Solution: Interpreted languages
An interpreted language uses a program called an
interpreter to translate the source code in
machine language statement-by-statement – it is
not compiled to run on any one particular
platform.
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THE JAVA PROGRAMMING
LANGUAGE
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Released in 1995.
An interpreted language, Java source code is
compiled into Java bytecode.
The Java Virtual Machine (JVM) interprets and
runs the Java bytecode regardless of the
computer architecture.
Supports Object-Oriented Programming (OOP), a
programming concept that allows us to represent
concepts as “objects” which we can instantiate
and use.
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JAVA FUN FACTS
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Most Android smartphone apps are written using
Java. A large amount of the Android operating
system is also written in Java
Javascript, commonly used in web-based settings,
is nothing like Java. Kind of.
The Java syntax is very similar to C/C++. Since
Java is platform-independent, it does not permit
as much communication with the computer
hardware as C/C++.
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JAVA FUN FACTS
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Some argue that Java is not efficient in comparison to
C/C++. In Java, you can free up memory by simply
not using it anymore. In C/C++, memory must be
cleared by the programmer. This allows for stronger
control over resources.
Java has several classes that programmers can
override and manipulate for special uses:
Applet - programs that are embedded in other applications
(commonly in web pages)
 Servlets – allows programmers to handle web server
requests in a custom manner
 JavaServer Pages (JSPs) – allow for dynamic webpage
creation
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WHERE DO I TYPE MY PROGRAMS?
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We will be typing our Java programs in one of
two IDEs (Integrated Developer Environments):
Eclipse by IBM
 NetBeans, an open source IDE sponsored by Oracle
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Both IDEs are installed on the lab computers.
Last year, students used Eclipse and it was slow.
 This year, we’ll try NetBeans.
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A Java program written using Eclipse will work
in NetBeans – it’s your choice!
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