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An Introduction to Java
Programming and
Object-Oriented Application
Development
Chapter 7
Characters, Strings, and Formatting
Brief Review of the char Data Type
• Recall a char is one of eight _________ types
• A character is any symbol represented by
Unicode
• A char is always expressed inside single quotes
• Every individual character has an equivalent
________ value
• The methods of the Character class
manipulate characters
An Introduction to Java Programming and Object-Oriented
Application Development
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Brief Review of the char Data
Type (continued)
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Application Development
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Methods in the Character Class
• The Character class is a __________ class
• The Integer and Double classes are also
wrapper classes
• Each primitive type has a corresponding
wrapper class
• A wrapper class ‘wraps’ the value of a primitive
type within an object so methods can be applied
An Introduction to Java Programming and Object-Oriented
Application Development
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Methods in the Character Class
(continued)
• charValue retrieves the character stored in the
Character object
• compareTo returns the difference in _________
values for two characters
• equals is true if two characters are identical
• isDigit is true if a character is in [0-9]
• isLetter is true if a character is in [a-z or A-Z]
An Introduction to Java Programming and Object-Oriented
Application Development
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Methods in the Character Class
(continued)
• isWhiteSpace is true if the character is a
space
• isWhiteSpace returns false if the character is
newline, tab, etc.
• toLowerCase changes uppercase to lowercase
• toUpperCase changes lowercase to uppercase
An Introduction to Java Programming and Object-Oriented
Application Development
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Brief Review of the String Class
• Recall a string is an object
– String myStr = “Johnson”
– String myStr = new String( “Johnson” )
• Recall the methods equals, length and
substring
• A string is a __________ variable that contains the
memory address of an array of characters
• Two classes StringBuilder and
StringTokenizer manipulate strings
An Introduction to Java Programming and Object-Oriented
Application Development
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Brief Review of the String Class
(continued)
• StringBuilder provides methods to
manipulate and build strings
• StringTokenizer breaks strings into _______
• A token is a group of characters within a string
• Tokens are separated by ___________
• The tokens in this sentence are delimited by
white space
An Introduction to Java Programming and Object-Oriented
Application Development
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The StringBuilder Class
• A String object is ____________
– i.e., once created it can never be changed
• StringBuilder allows strings to be modified
• StringBuilder is in the java.lang package
• All methods in StringBuilder are _________
(i.e., can be called only by objects, not the class)
An Introduction to Java Programming and Object-Oriented
Application Development
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The StringBuilder Class
(continued)
• append adds text to an existing
StringBuilder object
• insert inserts a second argument just after the
position given by the first argument
• deleteCharAt deletes a single character from
a StringBuilder at a given position
• replace replaces all occurrences of one
character with another
• toString creates a _______ that contains the
data from the StringBuilder object
An Introduction to Java Programming and Object-Oriented
Application Development
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The StringTokenizer Class
• StringTokenizer is in the _________ package
• StringTokenizer breaks a string into tokens
– Create the string to be tokenized
– Create the StringTokenizer object linked to the
string
– Apply the StringTokenizer object to the string to
get a token
• nextToken and countTokens are nonstatic
An Introduction to Java Programming and Object-Oriented
Application Development
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The printf and format Methods
• We have been using System.out.println
and string concatenation ( + )
• Instead of print and println, you can use
printf and format
An Introduction to Java Programming and Object-Oriented
Application Development
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The printf and format Methods
(continued)
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Application Development
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The printf and format Methods
(continued)
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Application Development
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The printf and format Methods
(continued)
• printf takes a format string and a string
variable: printf(“Cost: $%.2f\n”, cost );
• The format specifier begins with %, ends with a
conversion character: %.2f
• Conversion suffix characters may follow the
conversion characters
• Integers use conversion characters d and x
• Floating points use conversion characters e, E,
f, and g
An Introduction to Java Programming and Object-Oriented
Application Development
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The printf and format Methods
(continued)
• Characters and strings use the conversion
characters C and S
• Dates and times use the conversion character
t, possibly with suffix characters C, A, B, d, Y
• The argument index specifies the argument to
which the format specifier applies
– $1 is the first, $2 is the second,…, $n is the nth
• The field width is the number of spaces an
argument occupies
• The precision is the number of decimal places
An Introduction to Java Programming and Object-Oriented
Application Development
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The format Method
• The printf method displays to the command
window
• printf cannot be used to output to a GUI or file
• The format method in the Formatter class
can output to a GUI or file
• format is identical to printf
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Application Development
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The format Method (continued)
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Application Development
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