An Introduction to Java Programming and Object-Oriented Application Development

1. An Introduction to Java Programming and Object-Oriented Application Development Chapter 7 Characters, Strings, and Formatting

2. 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

3. Brief Review of the char Data Type (continued) An Introduction to Java Programming and Object-Oriented Application Development

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. The printf and format Methods (continued) An Introduction to Java Programming and Object-Oriented Application Development

14. The printf and format Methods (continued) An Introduction to Java Programming and Object-Oriented Application Development

15. 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

16. 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

17. 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 An Introduction to Java Programming and Object-Oriented Application Development

18. The format Method (continued) An Introduction to Java Programming and Object-Oriented Application Development