Slide1 : Chapter 3
Arithmetic Expressions
Chapter 3 Topics : Chapter 3 Topics Overview of Java Data Types
Numeric Data Types
Declarations for Numeric Expressions
Simple Arithmetic Expressions
Compound Arithmetic Expressions
Additional Mathematical Methods
Value-Returning Class Methods
Additional String Operations
Applications with Multiple Class File
Slide3 : Java Data Types reference array interface class primitive integral boolean byte char short int long floating point float double
Primitive and Reference Types : Primitive and Reference Types
letter
char letter;
String title;
String book;
letter = ‘J’;
title = “Problem Solving”;
book = title;
Primitive and Reference Types : Primitive and Reference Types
letter
title
char letter;
String title;
String book;
letter = ‘J’;
title = “Problem Solving”;
book = title;
Primitive and Reference Types : Primitive and Reference Types
letter
title
book
char letter;
String title;
String book;
letter = ‘J’;
title = “Problem Solving”;
book = title;
Primitive and Reference Types : Primitive and Reference Types
letter
title
book
char letter;
String title;
String book;
letter = ‘J’;
title = “Problem Solving”;
book = title; ‘J’
Primitive and Reference Types : Primitive and Reference Types
letter
title
book
char letter;
String title;
String book;
letter = ‘J’;
title = “Problem Solving”;
book = title; 2003 “Problem Solving” Memory Location 2003 ‘J’
Primitive and Reference Types : Primitive and Reference Types
letter
title
book
char letter;
String title;
String book;
letter = ‘J’;
title = “Problem Solving”;
book = title; 2003 “Problem Solving” Memory Location 2003 2003 ‘J’
Primitive and Reference Types : Primitive and Reference Types
letter
title
book
char letter;
String title;
String book;
letter = ‘J’;
title = “Problem Solving”;
book = title; 2003 “Problem Solving” Memory Location 2003 2003 ‘J’
Primitive Data Types in Java : Primitive Data Types in Java Integral Types
can represent whole numbers and their negatives when declared as short, int, or long
can represent single characters when declared as char
Floating Point Types
represent real numbers with a decimal point
declared as float or double
Samples of Java Data Values : Samples of Java Data Values int sample values
4578 -4578 0
double sample values
95.274 95. .265
char sample values
‘B’ ‘d’ ‘4’ ‘?’ ‘*’
Exponential (Scientific) Notation : Exponential (Scientific) Notation 2.7E4 means 2.7 x 10 4 =
2.7000 =
27000.0
2.7E-4 means 2.7 x 10 - 4 =
0002.7 =
0.00027
More About Floating Point Types : More About Floating Point Types Floating-point types have an integer part and a fractional part, with a decimal point in between; either the integer part or the fractional part, but not both, may be missing
EXAMPLES 18.4 500. .8 -127.358
Alternatively, floating point values can have an exponent, as in scientific notation; the number preceding the letter E doesn’t need to include a decimal point.
EXAMPLES 1.84E1 5E2 8E-1 -.127358E3
Recall ... : Recall ... Named constant declaration
final double PI = 3.14159;
final String HOME = “Texas”;
final int TEXAS_TEMP = 95;
Variable declaration
String address;
char initial;
int dailyTemp;
What is an Arithmetic Expression? : What is an Arithmetic Expression? An arithmetic expression is a valid arrangement of variables, constants, operators and parentheses
An expression can be evaluated to compute a value of a given type
The value of the expression
9.3 * 4.5 is 41.85
Division Operator : Division Operator The result of the division operator depends on the type of its operands
If one or both operands has a floating type, the result is a floating point type (float or double); otherwise, the result is an integral type
EXAMPLES
11 / 4 has value 2
11.0 / 4.0 has value 2.75
11 / 4.0 has value 2.75
Modulus Operator : Modulus Operator The modulus operator % when used with integer type operands has an integer type result
Its result is the integer type remainder of an integer division
EXAMPLE
11 % 4 has value 3 because ) 4 11 2 and Remainder = ?
Some Java Operators : Some Java Operators Precedence Operator Description
Higher () Parentheses
+ Positive
- Negative
* Multiplication
/ Division
% Modulus (remainder)
+ Addition
- Subtraction
Lower = Assignment
Precedence : Precedence Precedence determines which operator is applied first in an expression having several operators
Associativity : Associativity Left to right Associativity means that in an expression having 2 operators with the same priority, the left operator is applied first
In Java, the binary operators
* , / , % , + , - are all left associative
Expression 9 - 5 - 1 means (9 - 5) - 1
4 - 1
3
Evaluate the Expression : 7 * 10 - 5 % 3 * 4 + 9
means (7 * 10) - 5 % 3 * 4 + 9
70 - 5 % 3 * 4 + 9
70 - (5 % 3) * 4 + 9
70 - 2 * 4 + 9
70 - (2 * 4) + 9
70 - 8 + 9 (70 - 8) + 9
62 + 9
71 Evaluate the Expression
Parentheses : Parentheses Parentheses can be used to change the usual order
Parts in () are evaluated first
Evaluate
(7 * (10 - 5) % 3) * 4 + 9
(7 * 5 % 3) * 4 + 9
(35 % 3) * 4 + 9
2 * 4 + 9
8 + 9
17
Slide24 : More Java Operators 8 int age;
age = 8;
age = age + 1; age 9 age
Slide25 : Prefix Form: Increment Operator 8 int age;
age = 8;
++age; age 9 age
Slide26 : Postfix form: Increment Operator 8 int age;
age = 8;
age++; age 9 age
Slide27 : Decrement Operator 100 int dogs;
dogs = 100;
dogs--; dogs 99 dogs
Which form to use? : Which form to use? When the increment (or decrement) operator is used in a “stand alone” statement solely to add one (or subtract one) from a variable’s value, it can be used in either prefix or postfix form. dogs--; --dogs; USE EITHER
BUT... : BUT... When the increment (or decrement) operator is used in a statement with other operators, the prefix and postfix forms can yield different results. LET’S SEE HOW. . .
Slide30 : int alpha;
int num;
num = 13;
alpha = ++num * 3; “First increment, then use”
“Use, then increment” : int alpha;
int num;
num = 13;
alpha = num++ * 3; 13 13 39 14 “Use, then increment”
Integral Types : Integral Types Type Size in Bits Minimum Value to Maximum Value
byte 8 -128 to 127
short 16 -32,768 to 32,767
int 32 -2,147,483,648 to 2,147,483,647
long 64 -9,223,372,036,854,775,808 to
+9,223,372,036,854,775,807
Sizes of Integral Java Types : Sizes of Integral Java Types byte 8 bits
short 16 bits
int 32 bits
long 64 bits
Using one byte (= 8 bits), : Using one byte (= 8 bits), HOW MANY DIFFERENT NUMBERS CAN BE REPRESENTED USING 0’s and 1’s?
Each bit can hold either a 0 or a 1. So there are just two choices for each bit, and there are 8 bits.
2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 = 28 = 256
0 1 1 0 0 0 1 1
Similarly, using two bytes (= 16 bits), : Similarly, using two bytes (= 16 bits), 216 = 65536
DIFFERENT NUMBERS CAN BE REPRESENTED.
If we wish to have only one number representing the integer zero, and half of the remaining numbers positive, and half negative, we can obtain the 65,536 numbers in the range below :
-32768 . . . . 0 . . . . 32767
More about Floating-Point Types : More about Floating-Point Types
In Java floating-point literals like 94.6 without a suffix are of type double by default
To obtain another floating point type constant a suffix must be used
The suffix F or f denotes float type, as in 94.6F
Floating Point Types :
Type Size in Bits Range of Values
float 32 +1.4E - 45 to
+3.4028235E+38
double 64 +4.9E - 324 to
+1.7976931348623157E+308 Floating Point Types
Assignment Operator Syntax : Variable = Expression
First, Expression on right is evaluated
Then the resulting value is stored in the memory location of Variable on left
NOTE: An automatic type conversion occurs after evaluation but before the value is stored if the types differ for Expression and Variable Assignment Operator Syntax
What value is stored? : What value is stored? double a;
double b;
a = 8.5;
b = 9.37;
a = b; a b a b 8.5 9.37 ? ?
Slide40 : What is stored? ? float someDouble;
someDouble
someDouble = 12; // implicit type conversion someDouble 12.0
Slide41 : What is stored? ? int someInt;
someInt
someInt = 4.8; // implicit type conversion someInt 4
Type Casting is Explicit Conversion of Type : Type Casting is Explicit Conversion of Type int(4.8) has value 4
double(5) has value 5.0
double(7/4) has value 1.0
double(7) / double(4) has value 1.75
Some Expressions : Some Expressions int age;
EXAMPLE VALUE
5 + 8 13
5 / 8 0
6.0 / 5.0 1.2
double (4 / 8) 0.0
double (4) / 8 0.5
What values are stored? : What values are stored? double loCost;
double hiCost;
loCost = 12.342;
hiCost = 12.348;
loCost = (double) ((int) (loCost * 100.0 + 0.5)) / 100.0;
hiCost = (double) ((int) (hiCost * 100.0 + 0.5)) / 100.0;
Slide45 : Values were rounded to 2 decimal places 12.34 hiCost 12.35
loCost
Write a Java expression . . . : Write a Java expression . . . To find the larger of myAge and yourAge and place it in variable older
int older;
?
Write a Java expression . . . : Write a Java expression . . . To find the larger of myAge and yourAge and place it in variable older
int older;
. . .
older = Math.max(myAge, yourAge);
class method parameters
max is a class method
Write a Java expression . . . : Write a Java expression . . . To find the square root of b2 - 4ac and place it in variable d
double a, b, c, d;
?
Write a Java expression . . . : Write a Java expression . . . To find the square root of b2 - 4ac and place it in variable d.
double a, b, c, d;
. . .
d = Math.sqrt(b*b - 4.0*a* c);
sqrt is a _________ method
Additional String Methods : Additional String Methods Method length returns an int value that is the number of characters in the string
String name = “Donald Duck”;
numChars;
numChars = name.length();
instance method
length is an instance method
String Methods Continued : String Methods Continued Method indexOf searches a string to find a particular substring, and returns an int value that is the beginning position for the first occurrence of that substring within the string
Character positions begin at 0 (not 1)
The substring argument can be a literal String, a String expression, or a char value
If the substring could not be not found, method indexOf returns value -1
String Methods Continued : String Methods Continued Method substring returns a substring of a string, but does not change the string itsel
The first parameter is an int that specifies a starting position within the string
The second parameter is an int that is 1 more than the ending position of the substring
Remember: positions of characters within a string are numbered starting from 0, not from 1.
Slide53 : What value is returned? // Using methods length, indexOf, substring
String stateName = “Mississippi”;
stateName.length(); ?
stateName.indexOf(“is”); ?
stateName.substring(0, 4); ?
stateName.substring(4, 6); ?
stateName.substring(9, 11); ?
Inputting Numeric Values : Inputting Numeric Values If readLine inputs strings, how can we input numbers?
We convert the strings to the numbers they represent.
“69.34” becomes 69.34
“12354” becomes 12354
Yes, but how?
Predefined Numeric Classes : Predefined Numeric Classes Built-in Type Class
int Integer
long Long
float Float
double Double
parseInt, parseLong, parseFloat, parseDouble
are class methods for translating strings to numeric values
Converting Strings to Numbers : Converting Strings to Numbers int intNumber;
System.out.println(“Enter an integer: “);
intNumber = Integer.parseInt(inData.readLine());
class method Buffered- method
Reader
object argument to parseInt method
Applications Programming Interface : Applications Programming Interface Public methods of a class provide the interface between the programmer’s code and the Java class objects. Applications Programming Interface (API) programmer’s
code predefined
class shared
boundary
An object of class Double : An object of class Double Private data
and
methods .
.
. doubleValue MAX_VALUE MIN_VALUE parseDouble API
Converting a String to a Double Value : Converting a String to a Double Value
double price ;
price = Double.parseDouble(inData.readLine());
string converted to double value String object
Interacting Classes : Interacting Classes class Name
{…}
class Employee
{import Name;
…}
public class Payroll
{import Employee;
public static void main(…)…{}
…)