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…