代码不打印任何内容

Question

I am writing code that reads in a text file through the command line arguments in the main method and prints out each word in it on its own line without printing any word more than once, it will not print anything, can anyone help?

import java.util.*;
import java.io.*;
public class Tokenization {
public static void main(String[] args) throws Exception{
String x = "";
String y = "";

File file = new File(args[0]);
Scanner s = new Scanner(file);



String [] words = null;
while (s.hasNext()){
x = s.nextLine();
}
words = x.split("\\p{Punct}");


String [] moreWords = null;
for (int i = 0; i < words.length;i++){
    y = y + " " + words[i];
}
moreWords = y.split("\\s+");


String [] unique = unique(moreWords);
for (int i = 0;i<unique.length;i++){
    System.out.println(unique[i]);
}
s.close();
}



public static String[] unique (String [] s) {
String [] uniques = new String[s.length];
for (int i = 0; i < s.length;i++){
    for(int j = i + 1; j < s.length;j++){
        if (!s[i].equalsIgnoreCase(s[j])){
        uniques[i] = s[i];  
        }
    }
}
return uniques;
}
}

Answer 1

You have several problems:

1. you're reading whole file line by line, but assign only last line to variable x
2. you're doing 2 splits, both on regexp, it is enough 1
3. in unique - you're filling only some parts of array, other parts are null

Here is shorter version of what you need:

import java.io.File;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Tokenization {
    public static void main(String[] args) throws Exception {
        Set<String> words = new HashSet<String>();
        try {
            File file = new File(args[0]);
            Scanner scanner = new Scanner(file);
            while (scanner.hasNext()) {
                String[] lineWords = scanner.nextLine().split("[\\p{Punct}\\s]+");
                for (String s : lineWords)
                    words.add(s.toLowerCase());
            }
            scanner.close();
        } catch (Exception e) {
            System.out.println("Cannot read file [" + e.getMessage() + "]");
            System.exit(1);
        }

        for (String s : words)
            System.out.println(s);
    }
}