Extracting characters and words from a string

I want to scan an input line character by character and produce Strings based on valid tokens which are “true”, “false”, “^” “&”, “!”, “(”, “)”

For example if i was given a string such as String line = true & ! (false ^ true) String line = true & ! (false ^ true)

I would have to produce the tokens "true", "&", "!", "(", "false", "^", "true", ")"

I have been trying to use split() to divide the string into tokens and store them in an array like this String[] result = line.split(" ") , and then just using a bunch of if-statements inside a loop to see if the token at that index matches any of the valid tokens and just returning the token. this is kind of what i have been trying to use so far

for(int i = 0; i < line.length();i++){
    if(result[i].equals("true") || result[i].equals("false") || result[i].equals("^") 
        || result[i].equals("&") || result[i].equals("!") || result[i].equals("(")
        || result[i].equals(")")){
        nextToken = result[i];
}

but obviously this wont extract valid tokens that are adjacent to one another, such as when the string contains something like this (true or this true^false , which should return three tokens being "true", "^", "false" . Is there a way to divide a string that doesn't contain spaces or any special characters into tokens i am interested in?

---

So long as the input is accurate, the following will tokenize your input:

public class Tokenizer {

    public static void main(String[] args) {

        // true, false, ^ &, !, (, )
        String SYMBOLS = "^&!()";

        String line = "true&!(false^true)";
        List<String> tokens = new ArrayList<String>();

        char[] in = line.toCharArray();
        for (int i = 0; i<in.length; i++) {
            if (in[i] == ' ')
                continue;
            if (SYMBOLS.indexOf(in[i]) >= 0) {
                tokens.add(String.valueOf(in[i]));
            } else if (in[i] == 't') {
                tokens.add("true");
                i += "true".length()-1;
            } else if (in[i] == 'f') {
                tokens.add("false");
                i += "false".length()-1;
            }
        }

        for (String token : tokens)
            System.out.println(token);

    }
}

Producing output:

true
&
!
(
false
^
true
)

---

Try using delimiters. They will separate strings based on whatever you set as the tokens. I would take a look at this question for more information: How do I use a delimiter in Java Scanner?

---

Edit :-

if you need the exact count in the exact order you could do this :-

public static void main(String[] args)
{
    final String TOKENS = "true,false,!,),(";
    String [] splittedTokens = TOKENS.split(",");
    String Data = "'true','^','false'";

    ArrayList <String> existingTokens = new ArrayList<String>();
    for(int i = 0; i < splittedTokens.length; i++)
    {
        if(Data.contains(splittedTokens[i]))
        {
            existingTokens.add(splittedTokens[i]);
        }
    }

    for(int i = 0; i < splittedTokens.length; i++)
    {
        int count = 0;
        for(int j = 0; j < existingTokens.size(); j++)
        {
            if(splittedTokens[i].equals(existingTokens.get(j)))
            {
                count++;
            }
        }
        System.out.println("Number of "+splittedTokens[i]+" = "+count);
    }
}

if you only need all the tokens that the string contains :-

public static void main(String[] args)
{
    final String TOKENS = "true,false,!,),(";
    String [] splittedTokens = TOKENS.split(",");
    String Data = "true^false";

    for(int i = 0; i < splittedTokens.length; i++)
    {
        if(Data.contains(splittedTokens[i]))
        {
            System.out.println("The String Contains "+ splittedTokens[i]);
        }
    }
}

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