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CMSC 150INTRODUCTION
TOCOMPUTING
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 CEOQuoted from Michael J. Miller’s ForwardThinking blog
Homework, due Wednesday 1/18 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
Compiler
JavaProgra
m(Source)
JavaProgra
m(Source)
JavaProgram
(Byte Code)
JavaProgram
(Byte Code)
JavaVirtualMachin
e
You write the .java source codeinto a text file using an IDE, e.g., BlueJ
Compiler
The compiler is a program thatconverts source to binary; Included as part of Java
JavaProgra
m(Source)
JavaProgra
m(Source)
JavaProgram
(Byte Code)
JavaProgram
(Byte Code)
JavaVirtualMachin
e
Compiling & Executing
Compiler
JavaProgra
m(Source)
JavaProgra
m(Source)
JavaProgram
(Byte Code)
JavaProgram
(Byte Code)
JavaVirtualMachin
e
The .class byte code file (binary) can be executed
Compiling & Executing
Compiler
JavaProgra
m(Source)
JavaProgra
m(Source)
JavaProgram
(Byte Code)
JavaProgram
(Byte Code)
JavaVirtualMachin
e
Java VM is a program thatexecutes byte code instructions on the CPU
Compiling & Executing
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 alsosaved to disk
Your Program’s State
When you run the program,the Java VM loads thebinary version into RAM…
Your Program’s State
so that the instructions canbe executed on the CPU
Let’s Move Into BlueJ…