// DrJava saved history v2

2.0

5 + 3

// Java has 8 primitive types.

5 / 2

5.0 / 2.0

5 / 2.0

5.0 / 2

1.0 / 3

// A type is a set of values and a set of operations that 

// can be performed on those values.

// So far we've seen type int and type double 
// here is type float:
1.0f / 3

// type double has twice as many significant digits as float

'a'
// 'a' is a character literal (character value)

'a' + 1

'a' + 'b'

// each character has a numeric value

// 'a' has the value 97

// 'b' has the value 98

'a' + 'b'

'a' / 2

// some values can be converted from one type to another

// int, double, float, char

// type boolean

// values: true, false

// operations: &&, ||, ! (and, or, not)

!true

!false

4 < 2
! 4 < 2
! (4 < 2)
! ((4) < 2)
! (((4) < 2))
true && false

false && true

false && false

true && true

// && evaluates to true if both operands are true, and 

// if evaluates to false otherwise

true || false

false || true

false || false

true || true

// || evaluates to true if at least on of the operands is

// true, and evaluates to false otherwise

!true && true

// order of precendence:! && ||

true + 8

true && 0

// Three more types: short, long, byte

// These are all able to store integer values, but have

// smaller ranges than type int.
10000000000
10000000000L

Integer.MIN_VALUE

Integer.MAX_VALUE

Short.MIN_VALUE

Short.MAX_VALUE


// A non-primitive type: String

"hello"

"hello" + '!' // + is concatenation

"hello everybody!"

"hello everybody!" + ' '

int n;

// In the statement above, we declared a variable named n,

// which can hold int values.

n = 8;

n

n + 1

// Variable: a name with an associated type.

// Variable declaration: <type> <name>;

// Variable assignment: <name> = <value>;

double x;

x

x = 4.5;

x + 1

x = 1.2;

x + 1

// If we declare a double variable, but don't assign it

// a value, then it will have the value 0.0

int mynum
mynum
int 0abc
//varaible name cannot start with a number
int a0
iny mySalary
int mySalary
int day = 2
mySalary
day+5
mySalary*day
int _sfsafdfldsakjf9320432493214ewj
day
day = 2.3   
day = 2.3f   //enforcing a float
day = (int 2.3f)
day = (int 2.3)    
day = int 2.3   
day = int (2.3)   
(int 2.3)  
(int) 2.3  
day = (int) 2.3f    //explicit casting a float into int
day = (int) 2.9f    //it is truncated!
day = (int) 2.9     //explicit casting a double into int
day = (int) 2.9E201 //too big!
day
int d
d =1
day
day = 5
day
d
day = d + 5
d   
day 
day
day;  //in the "interaction pane" a ; at the end of statement mean don't display the result.
day