Chapter 2
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
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Object
Something with which we can interact with the program
Class
defines objects
System.out is an
object
print is different than println because
it does not advance to the next line
Objects are abstract because
we don’t have to think about it’s internal details
Encapsulation
Each object handles its own state
getter
used to ask an object the value of a variable
setter
allows you to ask an object to change the value
String is an object
yes
concatenation
when you use the + operator to connect a very long string
An escape sequence
begins with back slash, tell program to treat next letter specially
tab
\t
newline
\n
double quote
"
three steps to make a variable
instantiate: declare initialize: store use
assignment
stores a value into a variable
declaring multiple variable at once is
bad form
constant
final
type
a category or set of data values
3 primitive types
int double boolean
widening conversions
safe, do not lose information (int to double)
narrowing conversions
often lost information (double to in)
casting
we want a floating point result when dividing them, we cast a total result = (double) total / count;
pointer
a reference in the address, points to where the object is