Short conditions, java

Question

Hi,

i want to test if current char current is not ',', '-', '.' or ' ' Is there a shorter expression for:

if((current != ' ') || (current != '.') || ...)

any ideas?

EDIT:

I am just allowed to use the methods nextChar and getChar. I have to loop through the chars.

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;

public class WoerterZaehlen {
    public static void main(String[] args) {
        int wordCount = 0;
        /* Ab hier dürft ihr eigenen Code einfügen */
        char previous = ' ';
        while(hasNextChar()){
            char current = getChar();
            if(current != )
            //if(((current == ' ') || (current == '.') || (current == ',')) && ((previous != ' ') && (previous != ','))){
            //  wordCount++;
            //}
            previous = current;         
        }
        /* Ab hier dürft ihr nichts mehr ändern. */
        System.out.println("Anzahl der Wörter: " + wordCount);
    }

    private static InputStreamReader reader;
    private static int next = -1;

    public static boolean hasNextChar() {
        if(next != -1)
            return true;
        try {
            if(reader == null)
                reader = new InputStreamReader(new FileInputStream("textdatei.txt"));
            next = reader.read();

        } catch (IOException e) {
            System.out.println("Datei wurde nicht gefunden.");
        }
        return next != -1;
    }

    public static char getChar() {
        char c = (char) next;
        next = -1;
        return c;
    }
}

Answer 1

Try

String prohibitedChars = ",-. ";
boolean isProhibited = prohibitedChars.indexOf('-') > -1;

I cleaned it up to appear a bit nice, but if you're really after short then all you need is:

",-. ".indexOf('-') > -1;

EDIT:

You can still use this approach even if you are limited to getChar() and hasNextChar()

while(hasNextChar()){
    char current = getChar();
    if (",-. ".indexOf(current) > -1) {
        wordCount++;
    }
    previous = current;         
}

Answer 2

or if you wanted to be ridiculous put the chars in a static BitSet, and use isSet(current).

Unless this code is going to be executed millions of times, i'd stick with what you have, as code clarity is more important than unmeasurable performance gains.

Answer 3

If it is an entire string you are looping through you might want to consider using regular expressions.

An example of validating with regex: http://stackoverflow.com/questions/878715/checking-string-for-illegal-characters-using-regular-expression

The example is white-listing character rather than blacklisting. This would in most cases be the preferred option as there is far more legal character-ranges than illegal.

Answer 4

    BitSet unwantedChars=new BitSet();
    unwantedChars.set('.');
    unwantedChars.set(',');
    unwantedChars.set('-');
    unwantedChars.set(' ');
    char current=',';
    if(unwantedChars.get(current)) //true if unwanted char else false
    {
     //....
    }

Using Google Guava:

    CharMatcher unwantedChars=CharMatcher.anyOf("-,. ").precomputed();
    unwantedChars.apply(',');//true if unwanted char else false

Answer 5

if you are not allowed to use String.indexOf like in:

    if (" .,".indexOf(ch) != -1) {
        /* do something */
    } else {
        /* do if none of the above */
    }

use a switch like in

    switch (ch) {
        case ' ': case '.': case ',': /* do something */ break;
        default: /* do if none of the above */ break;
    }

(instead of saving the previous char, you could just use a boolean to indicate if the previous char was a word boundary or a legal word character)