CSIS 110 – Lecture 8
Chapter 3
Read Sections 3.1 through 3.3, 3.5
Who remembers what a type is?
What’s an example of a primitive type?
What’s it look like in memory?
Java also has a second variety of types: reference types
Reference Types
Example: String
String has a set of values and operations on those values
- concatenation
- length() : int
- charAt( int i ) : char
- subString( int m, int n ) : String
What's this look like in memory?
String phrase = "My dog has fleas.";
Instead of storing the value in the memory location, Java stores a reference to the value.
We say that an object variable 'references' or 'points to' an object of that type. Thus, a
String variable references an object whose type is String.
Another example:
Scanner stdin = new Scanner( System.in );
And another:
int x = 4;
int y = 7;
int width = 5;
int height = 3;
Rectangle box = new Rectangle( x, y, width, height );
with operations (methods) such as setSize, translate, contains, equals,...
