CODEWITHSUNDEEP
javastringtokenizer
Dio
Dio

Reputation: 21

How to work with the StringTokenizer class

I am supposed to evaluate a string by splitting the string in tokens using the StringTokenizer class. After that I am supposed to convert these tokens to int values, using "Integer.parseInt".

What I don't get is how I am supposed to work with the tokens after splitting them.

public class Tester {

    public static void main(String[] args) {
    String i = ("2+5");
    StringTokenizer st = new StringTokenizer(i, "+-", true);
    while (st.hasMoreTokens()) {
        System.out.println(st.nextToken());
    }
    int x = Integer.parseInt();
//what exactly do I have to type in here, do convert the token(s) to an int value?
}

}

So if I understand this right I now have three tokens. That would be: "2", "+" and "5".

How exactly do I convert these tokens to int values? Do I have to convert each of them seperatly?

Any help is appreciated.

Upvotes: 0

Views: 429

Answers (2)

Sergei Voychuk
Sergei Voychuk

Reputation: 171

To have a possibility to make some calculations with the Integers extracted from the String, you have to put them into an ArrayList. And you have to use try/catch operation to avoid a NumberFormatException. Further you can take the values directly from the ArrayList and do with them what you'd like. For example:

public static void main(String[] args) {
    ArrayList <Integer> myArray = new ArrayList <>();    
    String i = ("2+5");
        StringTokenizer st = new StringTokenizer(i, "+-/*=", true);
        while (st.hasMoreTokens()) {
            try {
            Integer stg = Integer.parseInt(st.nextToken(i));
            myArray.add(stg);
                }
            catch (NumberFormatException nfe) {};
            }

       System.out.println("This is an array of Integers: " + myArray);
       for (int a : myArray) {
           int x = a;
           System.out.println("This is an Integer: " + x);
       }
       int b = myArray.get(0);
       int c = myArray.get(1);
       System.out.println("This is b: " + b);
       System.out.println("This is c: " + c);
       System.out.println("This is a sum of b + c: " + (b + c));

}

As a result you'll get:

This is an array of Integers: [2, 5]
This is an Integer: 2
This is an Integer: 5
This is b: 2
This is c: 5
This is a sum of b + c: 7

Upvotes: 1

Maksim
Maksim

Reputation: 521

Maybe you can use this:

    String i = ("2+5");
    StringTokenizer st = new StringTokenizer(i, "+-", true);
    while (st.hasMoreTokens()) {
        String tok=st.nextToken();
        System.out.println(tok);

        //what exactly do I have to type in here, do convert the token(s) to an int value?
        if ("+-".contains(tok)) {
            //tok is an operand
        }
        else {
            int x = Integer.parseInt(tok);
        }       
    }

Upvotes: 1

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