1. Comp 114 Foundations of Programming Instructor: Prasun Dewan (Pr  sün Divän)

2. Hello World

3. Topics Assumed & Reviewed Types –int, double, char, String Variables, constants, expressions Arrays Assignment, conditionals, loops Procedures/Functions/Subroutines/Methods Parameters/arguments

4. Hello World package warmup; public class AHelloWorldGreeter { public static void main (String[] args) { System.out.println ("Hello World"); } Array of user-supplied arguments main header directory/library

5. Main Arguments user-supplied argument

6. Main Arguments package warmup; public class AnArgPrinter { public static void main (String[] args) { System.out.println (args[0]); } First argument args[0] args[1] Second argument...

7. Main Arguments user- supples no argument package warmup; public class AnArgPrinter { public static void main (String[] args) { System.out.println (args[0]); } program refers to argument array element exception!

8. Safe Arg Printer

9. Safe Arg Printer (edit in class) package warmup; public class ASafeArgPrinter { public static void main (String[] args) { //args.length gives number of elements in args array. }

10. Safe Arg Printer package warmup; public class ASafeArgPrinter { public static void main (String[] args) { if (args.length = = 1) System.out.println (args[0]); else { System.out.println("Illegal no of arguments:" + args.length + ". Terminating program"); System.exit(-1); }

11. If-else Statement if ( ) else

12. If-Else Statement true false

13. Compound Statement if (args.length = = 1) System.out.println (args[0]); else { System.out.println("Illegal no of arguments:" + args.length + ". Terminating program"); System.exit(-1); }

14. Nested if-else public static char toLetterGrade (int score) { if (score >= A_CUTOFF) return 'A'; else if (score >= B_CUTOFF) return 'B'; else if (score >= C_CUTOFF) return 'C'; else if (score >= D_CUTOFF) return 'D'; else return 'F'; }

15. Nested If-Else if (score >= A_CUTOFF) return 'A'; else if (score >= B_CUTOFF) return 'B'; else if (score >= C_CUTOFF) return 'C'; else if (score >= D_CUTOFF) return 'D'; else return 'F';

16. Nested If-Else

17. If Statement if (args.length = = 1) System.out.println (”args[0]”); if ( ) ;

18. Printing Multiple Arguments

19. Printing Multiple Arguments (edit in class) package warmup; public class AnArgsPrinter { public static void main(String[] args){ }

20. Printing Multiple Arguments package warmup; public class AnArgsPrinter { public static void main(String[] args){ int argNo = 0; while (argNo < args.length) { System.out.println(args[argNo]); argNo++; }

21. If Vs While Statement if ( ) ; while ( ) ;

22. if Statement true false

23. while Statement true false

24. while loop true false

25. Scanning Problem

26. char Constants char {letters, digits, operators...} ‘a’ ‘A‘ ‘1’ ‘< ‘ ‘’ 16 bits ‘ ‘’’ ‘\’’ Escape sequence ‘\n’ newline ‘ ‘\’ ‘\\’

27. Useful Escape Sequences

28. Ordering Characters ‘’‘a’…. position in ordered character list ordinal number (integer code) ….

29. Ordering Characters ‘’‘a’…. ‘b’‘c’‘z’…. ‘’‘A’…. ‘B’‘C’‘Z’…. ‘’‘0’…. ‘1’‘2’‘3’…. ‘a’ > ‘b’  false ‘B’ > ‘A’  true ‘4’ > ‘0’  true ‘0’ > ‘’  true ‘a’ > ‘A’  ??? ‘a’ > ‘0’  ???

30. Converting between Characters and their Ordinal Numbers (int) ‘a’  ordinal number of ’a’ (char) 55  character whose ordinal number is 55 (int) ‘’  0 0 (char) 0  ‘’ (int) ‘d’  ??? (char) 1  ??? (char) -1 (int) ‘c’ - (int) ‘a’  2 2 ‘c’ - ‘a’  2 2 Implicit cast to wider type (char) (‘c’ - 2)  ‘a’ (char) (‘A’ + 2)  ‘C’ (char) (‘C’ - ‘A’ + ‘a’)  ‘c’

31. String constants String{sequences of characters} “hello” “123” “hello 123” “a” variable size ‘a’ “” “hello\n\n123” “\”“\\” Object Type

32. Accessing String Components String s = “hello world”; s[0] s[1]... s.charAt(0)  ‘h’ s.charAt(1)  ‘e’ s.charAt(-1) s.charAt(11) StringIndexBounds exceptiom index s.length()  11 “ ”.length()  1 1  0 0

33. Accessing SubString “hello world”.substring(4,7)  s.charAt(beginIndex).. s.charAt(endIndex-1) s.substring(beginIndex, endIndex)  “o w” “hello world”.substring(4,4)  “” “hello world”.substring(7,4) StringIndexBounds exceptiom

34. String Processing int i = 0; while (i < s.length()) { System.out.println (s.charAt(i)); i++; } prints each character on separate line

35. Dissecting a Loop int i = 0; while (i < s.length()) { System.out.println (s.charAt(i)); i++; } loop condition loop body

36. Finer-grained Dissection int i = 0; while (i < s.length()) { System.out.println (s.charAt(i)); i++; } loop condition real body Resetting loop variable initalizing loop variables for (int i=0; i<s.length(); i++) System.out.println(s.charAt(i));

37. Meaning of For Loop S1; while ( E) { S3; S2; } for (S1; E; S2) S3 for (; E; S2) S3 while ( E) { S3; S2; } for (; E; ) S3 while ( E) { S3; } for (; ; ) S3 while ( true) S3;

38. Scanning Problem

39. Scanning Scanning image for text. Scanning frequencies for radio stations. Finding words in a sentence Finding identifiers, operators, in a program

40. Scanning JohnF.Kenndye token Input stream Token Stream token

41. Algorithm JohnF.Kenndye marker 0 Output: J

42. Algorithm JohnF.Kenndye marker 1 Output: J String inputLine

43. Algorithm JohnF.Kenndye marker 2 Output: J

44. Algorithm JohnF.Kenndye marker 5 Output: JF

45. Algorithm JohnF.Kenndye marker 6 Output: JF

46. Algorithm JohnF.Kenndye marker 8 Output: JFK

47. Algorithm JohnF.Kenndye marker 9 Output: JFK

48. Algorithm JohnF.Kenndye marker 14 Output: JFK

49. Solution (edit in class) package warmup; public class AnUpperCasePrinter { public static void main(String[] args){ }

50. Solution package warmup; public class AnUpperCasePrinter { public static void main(String[] args){ if (args.length != 1) { System.out.println("Illegal number of arguments:" + args.length + ". Terminating program."); System.exit(-1); } System.out.println("Upper Case Letters:"); int index = 0; while (index < args[0].length()) { if (isUpperCase(args[0].charAt(index))) System.out.print(args[0].charAt(index)); index++; } System.out.println(); } public static boolean isUpperCase(char c) { return (c >= 'A') && (c <= 'Z'); }

51. Printing Scanned Characters Backwards

52. Strings = Char Sequences JohnF.Kenndye hello String{sequences of characters} 143l0

53. Other Sequences as Predefined Types 100989910090 604050 {sequences of integers} 80 JFKFDR {sequence of Strings} JCBCRRGB 3.83.1 {sequences of doubles} 3.73.13.63.9 IntSequence DoubleSequence StringSequence

54. Other Sequences as Array Types 100989910090 604050 {sequences of integers} 80 {sequence of strings} 3.83.1 {sequences of doubles} 3.73.13.63.9 int[] double[] String[] JFKFDRJCBCRRGB

55. Initializing Array Declarations 10098991009080 int[] assignmentScores = {100, 98, 99, 100, 90 80}; 3.83.13.73.13.63.9 double[] gpas = {3.8, 3.1, 3.7, 3.1, 3.6, 3.9};String[] initials = {“JFK”, “FDR”, “JC”, “BC”, “GW”, “WW”}; JFKFDRJCBCGWWW assignmentScores Array Type Element Type Array Literal Array Variable

56. Array Operations String[] initials = {“JFK”, “FDR”, “JC”, “BC”, “GW”, “WW”}; JFKFDRJCBCGWWW initials.length  6 initials[0] initials[initials.length - 1] initials[initials.length]  ArrayIndexOutOfBoundsException public named constant initials[0] = “HT” HT initials[initials.length] = “HT”  ArrayIndexOutOfBoundsException Array Instance Size Fixed

57. Array Types have Variable-Size 100989910090 604050 80 int[] 10098991009080 int[] assignmentScores = {100, 98, 99, 100, 99, 80}; assignmentScores assignmentScores = {60, 40, 50}; assignmentScores 604050

58. Uninitializing Array Declaration int[] assignmentScores; assignmentScores null assignmentScores = {60, 40, 50}; assignmentScores 604050

59. Array Elements Uninitialized int[] assignmentScores = new int[3]; assignmentScores 000

60. Printing Scanned Characters Backwards

61. Variable-Size Collection filled part unfilled part current size maximum size

62. 3 J F K sizearray Variable-Size Collection filled part unfilled part current size maximum size

63. Variable-Size Collection static final int MAX_CHARS = 7; static char[] upperCaseLetters = new char[MAX_CHARS]; static int numberOfUpperCaseLetters = 0;

64. Solution package warmup; public class AReverseUpperCasePrinter { static final int MAX_CHARS = 5; static char[] upperCaseLetters = new char[MAX_CHARS]; static int numberOfUpperCaseLetters = 0; public static void main(String[] args){ if (args.length != 1) { System.out.println("Illegal number of arguments:" + args.length + ". Terminating program."); System.exit(-1); } int index = 0; System.out.println("Upper Case Letters:"); while (index < args[0].length()) { if (isUpperCase(args[0].charAt(index))) { System.out.print(args[0].charAt(index)); storeChar(args[0].charAt(index)); } index++; } System.out.println(); printReverse(); }

65. Solution (contd.) public static void storeChar(char c) { if (numberOfUpperCaseLetters == MAX_CHARS) { System.out.println("Too many upper case letters. Terminating program. "); System.exit(-1); } upperCaseLetters[numberOfUpperCaseLetters] = c; numberOfUpperCaseLetters++; } public static void printReverse() { System.out.println("Upper Case Letters in Reverse:"); for (int index =numberOfUpperCaseLetters - 1; index >= 0; index--) { System.out.print(upperCaseLetters[index]); }

66. Creating JBuilder Project

70. Adding a Class

73. Editing the Class

74. Saving the Class

75. Running the Class

76. Viewing the Results

77. Running with arguments

83. Setting a break point

84. Running in debugging mode

85. Stopping at breakpoint

86. Examining the call stack

87. Navigating main parameters

88. Stepping to next statement (F8)

89. Stepping to next statement

90. Variable values

91. Stepping Over

92. Stepping Into (F9)

93. Stepping Out

94. Resuming normal execution

95. Program termination