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package project3;
//
// WORDS. An iterator that reads lower case words from a text file.
//
// James Moen
// 19 Apr 17
//
import java.io.FileReader; // Read Unicode chars from a file.
import java.io.IOException; // In case there's IO trouble.
// WORDS. Iterator. Read words, represented as STRINGs, from a text file. Each
// word is the longest possible contiguous series of alphabetic ASCII CHARs.
class Words {
private int ch; // Last CHAR from READER, as an INT.
private FileReader reader; // Read CHARs from here.
private StringBuilder word; // Last word read from READER.
// Constructor. Initialize an instance of WORDS, so it reads words from a file
// whose pathname is PATH. Throw an exception if we can't open PATH.
public Words(String path) {
try {
reader = new FileReader(path);
ch = reader.read();
} catch (IOException ignore) {
throw new IllegalArgumentException("Cannot open '" + path + "'.");
}
}
// HAS NEXT. Try to read a WORD from READER, converting it to lower case as we
// go. Test if we were successful.
public boolean hasNext() {
word = new StringBuilder();
while (ch > 0 && !isAlphabetic((char) ch)) {
read();
}
while (ch > 0 && isAlphabetic((char) ch)) {
word.append(toLower((char) ch));
read();
}
return word.length() > 0;
}
// IS ALPHABETIC. Test if CH is an ASCII letter.
private boolean isAlphabetic(char ch) {
return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z';
}
// NEXT. If HAS NEXT is true, then return a WORD read from READER as a STRING.
// Otherwise, return an undefined STRING.
public String next() {
return word.toString();
}
// READ. Read the next CHAR from READER. Set CH to the CHAR, represented as an
// INT. If there are no more CHARs to be read from READER, then set CH to -1.
private void read() {
try {
ch = reader.read();
} catch (IOException ignore) {
ch = -1;
}
}
// TO LOWER. Return the lower case ASCII letter which corresponds to the ASCII
// letter CH.
private char toLower(char ch) {
if ('a' <= ch && ch <= 'z') {
return ch;
} else {
return (char) (ch - 'A' + 'a');
}
}
// MAIN. For testing. Open a text file whose pathname is the 0th argument from
// the command line. Read words from the file, and print them one per line.
public static void main(String[] args) {
Words words = new Words(args[0]);
while (words.hasNext()) {
System.out.println("'" + words.next() + "'");
}
}
}
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