麻省理工公开课(精选).pdf

: Java for
Lucy Mendel
MIT EECS
MIT IAP 2006
1
Course Staff
z Lucy Mendel
z Corey McCaffrey
z Rob Toscano
z Justin Mazzola Paluska
z Scott Osler
z Ray He
Ask us for help!
MIT IAP 2006 2
Class Goals
z Learn to program in Java
z Java
z Programming (OOP)
z problem sets are not supposed to take
you 20 hours!
z Tools, concepts, thinking
MIT IAP 2006
3
Logistics
z 5 days long, optional second week
z 2 hrs lecture, 1 hr lab
z End of week might be 1 hr lecture, 2 hr lab
z Breaks!
z Labs
z Work on homework with staff assistance (like LA
hours in )
z Mandatory even for listeners
z Each is expected to take ~1-2 hrs
MIT IAP 2006 4
Object Oriented Programming
z Objects have state
z A person is an object and has a name, age, SS#,
mother, &e.
z Programmers call methods on objects to
compute over and potentially modify that
state
z programmer: How old are you?
z object: I am 22.
z programmer: Today is your birthday!
z object: I have incremented my age by 1.
MIT IAP 2006
5
Java Program
package hello;
import ;
class HelloWorld {
String myString;
void shout() {
myString = new String("Hello, World!“);
(myString);
}
public static void main(String[] args) {
HelloWorld myHelloWorld = new HelloWorld();
();
}
}
MIT IAP 2006 6
Class
z Template for making objects
z Java is about objects Æ everything is in a
class
class HelloWorld { // classname
…<everything> …
}
MIT IAP 2006
7
Field
z Object state
class Human {
int age;
}
<class type> <variable name>;
MIT IAP 2006
8
Making objects
Human lucy = new Human();
z All object creation requires a “new”
z objects = instances (of classes)
z lucy is a pointer to the object
z We assign the constructed object to lucy
<type> <variable name> = <new o