1 | /*
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2 | * To change this template, choose Tools | Templates
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3 | * and open the template in the editor.
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4 | */
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5 | package util;
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6 |
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7 | import java.io.BufferedReader;
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8 | import java.io.File;
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9 | import java.io.FileInputStream;
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10 | import java.io.IOException;
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11 | import java.io.InputStreamReader;
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12 | import java.util.NoSuchElementException;
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13 |
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14 | /**
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15 | * A simple buffered text file reader which can read characters from a file.
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16 | *
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17 | * @author John
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18 | */
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19 | public class CharReader {
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20 |
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21 | private static final int CHAR_BUFFER_SIZE = 1000;
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22 | private char[] charBuffer;
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23 | private BufferedReader reader;
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24 | private int currentIndex;
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25 | private int lastIndex;
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26 |
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27 | public CharReader(File file, String charsetEncoding) throws IOException {
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28 | reader = new BufferedReader(new InputStreamReader(new FileInputStream(file), charsetEncoding));
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29 | charBuffer = new char[CHAR_BUFFER_SIZE];
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30 | currentIndex = lastIndex = 0;
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31 | }
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32 |
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33 | /**
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34 | * Returns true if the CharReader has another char in its input.
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35 | * @return true if and only if this CharReader has another char.
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36 | */
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37 | public boolean hasNextChar() {
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38 | if (currentIndex < lastIndex) {
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39 | return true;
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40 | }
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41 | read();
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42 | return currentIndex < lastIndex;
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43 | }
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44 |
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45 | /**
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46 | * Returns the next char from this CharReader.
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47 | * @return the next char.
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48 | * @throws NoSuchElementException if no more chars are available
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49 | */
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50 | public char nextChar() throws NoSuchElementException {
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51 | checkIndex(currentIndex);
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52 | return charBuffer[currentIndex++];
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53 | }
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54 |
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55 | /**
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56 | * Looks at the next char from this CharReader without removing it.
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57 | * @return the next char.
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58 | * @throws NoSuchElementException if no more chars are available
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59 | */
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60 | public char peek() throws NoSuchElementException {
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61 | checkIndex(currentIndex);
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62 | return charBuffer[currentIndex];
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63 | }
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64 |
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65 | /**
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66 | * Close the CharReader.
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67 | */
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68 | public void close() {
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69 | try {
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70 | reader.close();
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71 | } catch (IOException e) {
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72 | e.printStackTrace();
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73 | }
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74 | }
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75 |
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76 | /**
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77 | * Read a portion of characters into an array.
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78 | */
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79 | private void read() {
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80 | try {
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81 | lastIndex = reader.read(charBuffer, 0, charBuffer.length);
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82 | currentIndex = 0;
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83 | } catch (Exception e) {
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84 | e.printStackTrace();
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85 | }
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86 | }
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87 |
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88 | /**
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89 | * Throws a NoSuchElementException if the index is less then 0 or greater
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90 | * then char buffer length.
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91 | * @param index Index to check.
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92 | * @throws NoSuchElementException if the index is less then 0 or greater
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93 | * then the char buffer length.
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94 | */
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95 | private void checkIndex(int index) throws NoSuchElementException {
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96 | if (index < 0 || index >= charBuffer.length) {
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97 | throw new NoSuchElementException();
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98 | }
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99 | }
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100 | }
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