How to get character one by one from a string using string tokenizer in java

Question

I have a complex string and I just need to get each and every char in this string one by one. Here what I did, but at one place I am getting both /( I know what because there is a no delimiter between them. How can I overcome this?

Hear is my string : 3 + 4 * 2 / ( 1 - 5 )

My code:

StringTokenizer tokenizer = new StringTokenizer(mathExpression , "+-x/()");
StringTokenizer tokenizer2 = new StringTokenizer(mathExpression , "123456789");

while (tokenizer.hasMoreElements()) {           
  System.out.println(tokenizer.nextToken());            
}

while (tokenizer2.hasMoreElements()) {              
  System.out.println(tokenizer2.nextToken());               
}

Output :

3
4
2
1
5
+
x
/(
-
)

Answer 1

An instance of StringTokenizer behaves in one of two ways, depending on whether it was created with the returnDelims flag having the value true or false:

•If the flag is false, delimiter characters serve to separate tokens. A token is a maximal sequence of consecutive characters that are not delimiters.

•If the flag is true, delimiter characters are themselves considered to be tokens. A token is thus either one delimiter character, or a maximal sequence of consecutive characters that are not delimiters.

http://docs.oracle.com/javase/6/docs/api/java/util/StringTokenizer.html

 StringTokenizer(mathExpression , "+-x/()", true);

Answer 2

No need to reinvent the wheel. You can just use String#getChars() or String#toCharArray().

Answer 3

Why do you use a StringTokenizer? Just iterate the String:

for(int i = 0; i < myString.length(); i++) {
    char c = myString.charAt(i);
    // do something with c
}

If you're not directly interested in single chars but want to have all of them at once, you can also request a char[] from the string:

char[] chars = myString.toCharArray();

(Note that this will return a copy of the String-internal char array, so if you just want to process single chars, the first method might be less memory- and performance-intensive).