SORTING - Introduction to Java Programming: Comprehensive Version - page 888

39 merge((numberOfSegments + 1 ) / 2 , segmentSize * 2 , merge recursively

40 f3, f1, f2, targetfile);

41 }
42 else { // Rename f1 as the final sorted file
43 File sortedFile = new File(targetfile);
44

final sorted file

if (sortedFile.exists()) sortedFile.delete();

45 new File(f1).renameTo(sortedFile);

46 }
47 }
48
49 private static void mergeOneStep( int numberOfSegments,
50 int segmentSize, String f1, String f2, String f3)
51 throws Exception {
52 DataInputStream f1Input = new DataInputStream(
53 new BufferedInputStream( new FileInputStream(f1), BUFFER_SIZE));
54 DataOutputStream f2Output = new DataOutputStream(
55 new BufferedOutputStream( new FileOutputStream(f2), BUFFER_SIZE));
56
57 // Copy half number of segments from f1.dat to f2.dat
58 copyHalfToF2(numberOfSegments, segmentSize, f1Input, f2Output);
59 f2Output.close();
60
61 // Merge remaining segments in f1 with segments in f2 into f3
62 DataInputStream f2Input = new DataInputStream(
63 new BufferedInputStream( new FileInputStream(f2), BUFFER_SIZE));
64 DataOutputStream f3Output = new DataOutputStream(
65 new BufferedOutputStream( new FileOutputStream(f3), BUFFER_SIZE));
66
67

input stream f1Input

output stream f2Output

copy half segments to f2
close f2Output

input stream f2Input

output stream f3Output

mergeSegments(numberOfSegments / 2 , merge two segments

68 segmentSize, f1Input, f2Input, f3Output);

69
70 f1Input.close();
71 f2Input.close();
72 f3Output.close();
73 }
74
75

close streams

/** Copy first half number of segments from f1.dat to f2.dat */

76 private static void copyHalfToF2( int numberOfSegments,

77 int segmentSize, DataInputStream f1, DataOutputStream f2)

78 throws Exception {

79 // Same as Listing 23.13, so omitted

80 }
81
82 /** Merge all segments */
83 private static void mergeSegments( int numberOfSegments,
84 int segmentSize, DataInputStream f1, DataInputStream f2,
85 DataOutputStream f3) throws Exception {
86

// Same as Listing 23.14, so omitted

87 }
88
89 /** Merges two segments */
90 private static void mergeTwoSegments( int segmentSize,
91 DataInputStream f1, DataInputStream f2,
92 DataOutputStream f3) throws Exception {
93

// Same as Listing 23.15, so omitted

94 }
95
96

/** Display the first 100 numbers in the specified file */

97 public static void displayFile(String filename) {

display file

98 try {