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CMSC 150
INTRODUCTION
TO
COMPUTING
CS 150: Wed 11 Jan 2012
Quote of the Day
“A smartphone today has more computing power than
all of NASA did when it put a man on the moon in
1969.”
- Paul Otellini, Intel CEO
Quoted from Michael J. Miller’s ForwardThinking blog
Homework, due Wednesday 1/18
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p. 39 - 40: 2, 3, 7, 9
p. 127 - 129: 4, 6, 7, 8, 10, 11
p. 130: #4 and 5 (can be done on pencil and
paper or as a BlueJ project - use project name
hw1_<your_netid> as your project name, and be
sure to put your name in the comment at the top of
the .java file if you do this in BlueJ)
Bonus problem: p. 128: #6
Compiling & Executing
Java
Program
Compiler
(Source)
(Source)
You write the .java source code
into a text file using an IDE,
e.g., BlueJ
Java
Java
Program
Program
(Byte
(Byte Code)
Code)
Java
Virtual
Machine
Compiling & Executing
Java
Program
Compiler
(Source)
(Source)
The compiler is a program that
converts source to binary;
Included as part of Java
Java
Java
Program
Program
(Byte
(Byte Code)
Code)
Java
Virtual
Machine
Compiling & Executing
Java
Program
(Source)
(Source)
Compiler
Java
Java
Program
Program
(Byte
(Byte Code)
Code)
The .class byte code file
(binary) can be executed
Java
Virtual
Machine
Compiling & Executing
Java
Program
(Source)
(Source)
Compiler
Java
Java
Program
Program
(Byte
(Byte Code)
Code)
Java VM is a program that
executes byte code
instructions on the CPU
Java
Virtual
Machine
RAM vs. Hard Drive
Your Program’s State
Your .java source code file
is saved to disk
Your Program’s State
When you compile, the
.class binary file is also
saved to disk
Your Program’s State
When you run the program,
the Java VM loads the
binary version into RAM…
Your Program’s State
so that the instructions can
be executed on the CPU
Let’s Move Into BlueJ…