Java IO.pdf - Nguyen Dang Binh

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7.9 Thread Safety Java I/O The LittleEndianInputStream class is not perfectly thread-safe. Consider the readInt() method: public int readInt() throws IOException { } int byte1 = in.read(); int byte2 = in.read(); int byte3 = in.read(); int byte4 = in.read(); if (byte4 == -1 || byte3 == -1 || byte2 == -1 || byte1 == -1) { throw new EOFException(); } return (byte4
public void writeInt(int i) throws IOException { } out.write(i & 0xFF); out.write((i >>> 8) & 0xFF); out.write((i >>> 16) & 0xFF); // What happens if another thread preempts here? out.write((i >>> 24) & 0xFF); written += 4; Java I/O Suppose a second thread preempts the running thread where indicated in the previous code and writes unrelated data onto the output stream. The entire stream can be corrupted, because the bytes of the int are separated. The same synchronization tricks work here as well. However, all the problems I've noted here are shared by DataInputStream and DataOutputStream. Similar problems crop up in other filter stream classes. This leads to the following general principle for thread-safe programming: Never allow two threads to share a stream. The principle is most obvious for filter streams, but it applies to regular streams as well. Although writing or reading a single byte can be treated as an atomic operation, many programs will not be happy to read and write individual bytes. They'll want to read or write a particular group of bytes and will not react well to being interrupted. 7.10 File Viewer, Part 3 In Chapter 4, I introduced a FileDumper program that could print the raw bytes of a file in ASCII, hexadecimal, or decimal. In this chapter, I'm going to expand that program so that it can interpret the file as containing binary numbers of varying widths. In particular I'm going to make it possible to dump a file as shorts, unsigned shorts, ints, longs, floats, and doubles. Integer types may be either big-endian or little-endian. The main class, FileDumper3, is shown in Example 7.10. As in Chapter 4, this program reads a series of filenames and arguments from the command line in the main() method. Each filename is passed to a method that opens a file input stream from the file. Depending on the commandline arguments, a particular subclass of DumpFilter from Chapter 6 is selected and chained to the input stream. Finally, the StreamCopier.copy() method pours data from the input stream onto System.out. Example 7.10. The FileDumper3 Class import java.io.*; import com.macfaq.io.*; public class FileDumper3 { public static final int ASC = 0; public static final int DEC = 1; public static final int HEX = 2; public static final int SHORT = 3; public static final int INT = 4; public static final int LONG = 5; public static final int FLOAT = 6; public static final int DOUBLE = 7; 124
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Java I/O Elliotte Rusty Harold Publ
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III: Filter Streams ...............
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V: Appendixes .....................
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Preface Java I/O In many ways this
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Java I/O operations from moving byt
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Chapter 9 Chapter 10 Java I/O Chapt
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Chapter 17 Java I/O lining up the d
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Security Issues Java I/O I don't kn
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Java I/O Finally, although many of
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Part I: Basic I/O Java I/O 13
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Java I/O The word stream is derived
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Java I/O The java.util.jar package
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Java I/O For instance, according to
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Java I/O Java understands several d
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Java I/O commonly use an eight-bit
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Java I/O For the most part, these c
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Figure 1.1. An xterm console on Uni
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Java I/O If you absolutely must use
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Java I/O in Apple's Macintosh Runti
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Java I/O to work inside a web brows
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Java I/O bit pattern to a particula
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Java I/O The output is the same as
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OutputStream out = new NullOutputSt
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Figure 2.1. The StreamedTextArea co
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Java I/O When you call read(), you
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Java I/O try { byte[] b = new byte[
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Java I/O Once you have closed an in
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public class StreamCopier { } publi
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Chapter 4. File Streams Java I/O Un
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} } for (int i = 0; i < args.length
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Java I/O The FileOutputStream class
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Java I/O ASCII format is the defaul
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} } } Java I/O if (hex >= 16) Syste
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Java I/O Finally, many HTML files c
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Java I/O In particular, URL connect
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Java I/O Example 5.3 uses these ste
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Java I/O many available ports but o
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Java I/O inspecting the port. It kn
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} } } String response = "Hello " +
Page 80 and 81: } public void actionPerformed(Actio
Page 82 and 83: Chapter 6. Filter Streams Java I/O
Page 84 and 85: Java I/O output stream, out. Among
Page 86 and 87: Java I/O SourceFile???StringExtract
Page 88 and 89: 6.3 Buffered Streams Java I/O Buffe
Page 90 and 91: public boolean markSupported() Java
Page 92 and 93: The compiler rewrites this complica
Page 94 and 95: public class TeeCopier { } public s
Page 96 and 97: } } try { FileInputStream fin = new
Page 98 and 99: } public int available() throws IOE
Page 100 and 101: public class HexFilter extends Dump
Page 102 and 103: } } StreamCopier.copy(in, out); in.
Page 104 and 105: Java I/O the java.io.DataOutput int
Page 106 and 107: Java I/O Although other schemes are
Page 108 and 109: } public static void main(String ar
Page 110 and 111: Java I/O Since Java has no unsigned
Page 112 and 113: dout.close(); } catch (IOException
Page 114 and 115: Java I/O The DataInputStream class
Page 116 and 117: Java I/O The readLine() method read
Page 118 and 119: 7.7 Miscellaneous Methods Java I/O
Page 120 and 121: public synchronized void write(int
Page 122 and 123: ** * Writes a 4 byte Java float to
Page 124 and 125: } * possible that this number is te
Page 126 and 127: */ public byte readByte(int b) thro
Page 128 and 129: } Java I/O long byte4 = in.read();
Page 132 and 133: public static void main(String[] ar
Page 134 and 135: Table 7.2. Command-Line Switches fo
Page 136 and 137: } protected void fill() throws IOEx
Page 138 and 139: Chapter 8. Streams in Memory Java I
Page 140 and 141: UDP Byte array input and output str
Page 142 and 143: } } try { // So that the buffer doe
Page 144 and 145: Java I/O Otherwise, these classes j
Page 146 and 147: } } catch (IOException e) { // prob
Page 148 and 149: Java I/O legally unencumbered—tha
Page 150 and 151: Java I/O if it doesn't, it will com
Page 152 and 153: Java I/O The first method fills the
Page 154 and 155: public class DirectDeflater { } pub
Page 156 and 157: 9.1.2.1 Constructing inflaters Ther
Page 158 and 159: 9.1.2.7 An example Java I/O Example
Page 160 and 161: Java I/O stream itself, without hav
Page 162 and 163: Java I/O Each inflater input stream
Page 164 and 165: Java I/O This writes all remaining
Page 166 and 167: } } } FileOutputStream fout = new F
Page 168 and 169: } } } catch (IOException e) {System
Page 170 and 171: Java I/O Normally, the name argumen
Page 172 and 173: % java FancyZipLister temp.zip test
Page 174 and 175: Java I/O All high-order Unicode byt
Page 176 and 177: Java I/O the files to be stored in
Page 178 and 179: 9.3.3.2 Open the next zip entry Jav
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Java I/O Better checksum schemes us
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} } int b; while ((b = in.read()) !
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Java I/O example, under Unix, to ma
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Java I/O archive. If the signatures
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Java I/O public JarFile(String file
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Java I/O The java.util.jar.Attribut
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9.5.7 Manifest Java I/O What the ja
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public ZipEntry getNextEntry() thro
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Java I/O so throw a java.lang.Unsup
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within the space of the next few li
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Chapter 10. Cryptographic Streams J
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Java I/O • It should be difficult
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Figure 10.1. The four steps to calc
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Java I/O you only want to detect si
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public void reset() Java I/O In pra
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Java I/O After each successful call
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} byte[] result = md.digest(); for
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} } catch (Exception e) {System.err
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public class EasyFileDigest { publi
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Java I/O them your encryption (publ
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Java I/O DES, triple DES (DESede),
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IDEA RC2 RC4 Blowfish Java I/O The
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Figure 10.2. Encrypting data Java I
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} } catch (NoSuchAlgorithmException
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} } Java I/O } catch (InvalidKeySpe
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SecretKey blowfishKey = blowfishKey
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Java I/O public final byte[] doFina
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Java I/O A CipherInputStream object
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10.6.2 CipherOutputStream CipherOut
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} } byte[] newDigest = sha.digest()
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} } else if (args[firstFile].equals
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Java I/O Note how little we had to
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Chapter 11. Object Serialization Ja
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Java I/O To write an object onto a
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Java I/O Needless to say, this is a
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Java I/O java.awt.image.renderable
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Java I/O are not serializable, then
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11.5.1.5 Making nonserializable fie
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Java I/O output streams, but DataIn
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Figure 11.2. The serialver GUI Java
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public SerializableZipFile(File fil
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public class NetworkWindow extends
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private void writeObject(ObjectOutp
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} } Vector v = (Vector) oin.readObj
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Java I/O the resolveClass() method
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Example 11.6. Person import java.ut
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public class SealedPoint { } public
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Chapter 12. Working with Files Java
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Java I/O not begin with an @. Under
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Java I/O placing a minus sign befor
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Java I/O rush to snap up all the go
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System Properties System properties
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Java I/O complete list of the ASCII
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Win32 index.html MacOS index.html N
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Java I/O The path argument should b
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Java I/O assume the array returned
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Example 12.2. Paths import java.io.
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String canonicalPath = f.getCanonic
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Java I/O The isHidden() method, onl
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12.3.4 Manipulating Files Java I/O
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fin.close(); src.delete(); Java I/O
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public int hashCode() public boolea
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public class DirList { } File direc
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12.4 Filename Filters Java I/O You
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} } for (int i = 0; i < htmlFiles.l
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public RandomAccessFile(File file,
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Java I/O • Do not parse pathnames
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Figure 13.2. Motif standard Open di
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Java I/O Example 13.1 is a program
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} } // Work around annoying AWT non
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} // Clean up our windows, they won
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13.2.2 Displaying File Choosers Jav
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13.2.5 Custom Dialogs Java I/O File
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Figure 13.4. The choosable file fil
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Example 13.7. JavaChooser import ja
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13.2.7 Selecting Directories Java I
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public void setFileView(fileView) p
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13.2.12.1 Action events Java I/O Wh
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public TextFilePreview(JFileChooser
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13.3 File Viewer, Part 6 Java I/O W
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} } } theView.setText(""); OutputSt
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} } return deflated.isSelected(); p
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Java I/O Chapter 14. Multilingual C
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Java I/O the upper 128 characters o
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makeBlock("Telugu", 0x0C00, 0x0C7F)
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} } for (int i = 0; i < names.lengt
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14.3 Unicode Escapes Java I/O Curre
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0 0 0 0 0 x10 x9 x8 x7 x6 x5 x4 x3
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Character g = new Character('g'); C
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Java I/O two Latin letters. In uppe
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Java I/O tie, and a few similar cha
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Java I/O The most common type of ch
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Java I/O encoding into a new file c
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Java I/O String openingLineInUnicod
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Java I/O For example, given some Wr
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The flush() and close() methods flu
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15.4 The InputStreamReader Class Th
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Java I/O Similarly, to write text i
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Java I/O These methods behave like
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Java I/O Since string objects are i
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This class has three constructors t
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Do not use the newLine() method if
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Example 15.5. The cat Program impor
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There are four constructors in this
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PipedReader pr = new PipedReader();
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Example 15.7. SourceReader package
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Java I/O question is what to do if
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Java I/O numeric data. If they choo
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} public boolean isText() { if (thi
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default: } } else { LittleEndianInp
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public void init() { } this.addWind
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Chapter 16. Formatted I/O with java
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Java I/O variable salary 12 places
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Hebrew Hebrew Israel iw Hungarian R
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For example: Java I/O NumberFormat
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public void setMaximumIntegerDigits
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Java I/O Like other aspects of text
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Example 16.5. PercentTable import j
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Java I/O align the decimal points i
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Figure 16.1. The PrettiestTable app
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Java I/O This whole class is just a
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Java I/O Most number formats are in
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public int getMultiplier() public v
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Arabic (Saudi Arabia) Arabic (Sudan
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Slovak #,##0.### -1 234,56 #,##0.00
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16.6.2.1 Utility methods Java I/O F
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** * Concrete class for formatting
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} String integerField = digits.subs
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Chapter 17. The Java Communications
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javax.comm.CommPortIdentifier@be4c9
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} } } switch(com.getPortType()) { c
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Java I/O In this example, you see t
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17.2.5 Registering Ports For comple
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} public void run() { } try { byte[
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Java I/O The output buffer size is
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Java I/O Here's the results for bot
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Java I/O If the requested values ar
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Figure 17.1. PC DB-25 serial port t
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public abstract void setRTS(boolean
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Java I/O Steps 1 and 2 should be fa
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Java I/O standard messages on other
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Java I/O serial port events: when t
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17.5.5.3 Step 3 Java I/O In many ci
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Appendix A. Additional Resources Ja
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A.5 Data Compression Java I/O Java
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Java I/O "Developing International
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Appendix B. Character Sets Java I/O
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151 epa (end of guarded area) 183
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Java I/O Cp857 DOS ASCII plus Turki
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Java I/O As extensive as this list
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