Splitting string into an array

Question

I am attempting to split the components of a string into an array, so that they can be accessed more easily.

For example: 4+5= should become ['4','+','5','='].

Edit: - I would need consecutive numbers to be joined together, and whitespaces can be ignored. Thanks again!

are your strings always number-operator-number-equals or are there other possible strings? — Philipp
– Philipp, Commented Dec 25, 2012 at 20:20
I guess, you need to edit your question, as you need a parsed result and not just array of single characters. — mtk
– mtk, Commented Dec 25, 2012 at 20:31

Pshemo · Accepted Answer · 2012-12-25 20:55:03Z

2

You can solve it with regex lookaround mechanism.

String str = "10 * 10 - 40 + 100/2 = 110";

//but first lets remove white spaces (it will makes regex easier)
String strWithoutSpaces=str.replaceAll("\\s+", "");

String[] tokens = strWithoutSpaces.split("(?<=[-+*/=])|(?=[-+*/=])");

for (String t:tokens)
    System.out.print(t+",");

Output:

10,*,10,-,40,+,100,/,2,=,110,

answered Dec 25, 2012 at 20:55

Pshemo

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Comments

mtk · Accepted Answer · 2012-12-25 20:24:47Z

2

You can use

String str = "4+5=";
String[] tokens = str.split("(?!^)");
for (String s : tokens) {
    System.out.println(s);
}

This will output

answered Dec 25, 2012 at 20:24

mtk

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Comments

someone · Accepted Answer · 2012-12-25 20:33:50Z

0

You could use toCharArray() method

    String s ="4+5=";
    char [] stArr = s.toCharArray();
    for(char ss: stArr){
        System.out.println(ss);
    }

Out put

4
+
5
=

edited Dec 25, 2012 at 20:33

answered Dec 25, 2012 at 20:19

someone

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5 Comments

Rohit Jain Over a year ago

This will break for 45+45=90

Rohit Jain Over a year ago

Will again break. It now splits on empty string.

mtk Over a year ago

@Rohit I tested. Neither toCharArray broke nor empty split one. Please can you explain, why you envisage it would be wrong?

Rohit Jain Over a year ago

@mtk.. toCharArray will treat 4 and 5 as different characters in case of 45+45=90. OP want them to be together. It returns this array: - ['4', '5', '+', '4', '5'...]

mtk Over a year ago

@Rohit Thanks for that. I misinterpreted the question. My bad... Great answer to the other similar question.

ramesh · Accepted Answer · 2012-12-25 21:12:32Z

You could do something like this:

public static void main(String args[]) {
    String str = "45+5-26";
    String strArr[] = new String[str.length()];
    StringBuffer sb = new StringBuffer();
    int cnt = 0;
    for (int i = 0; i < str.length(); i++) {
        char ch = str.charAt(i);
        if (ch != '\0') {
            if (ch == ' ') {
                continue;
            }
            if (ch >= 48 && ch <= 57) {
                sb.append(ch);
                continue;
            } else {
                strArr[cnt++] = sb.toString();
                sb = new StringBuffer();
                // sb.append(ch);
            }
            strArr[cnt++] = ch + "";
            sb = new StringBuffer();
        }
    }
    strArr[cnt++] = sb.toString();
    sb = new StringBuffer();
    System.out.println("strArray: ");
    for (int i = 0; i < strArr.length; i++) {
        if (strArr[i] == null)
            break;
        System.out.println(strArr[i]);
    }
}

If you have only operators as the separator between the numbers this would be more easy to get the string tokens.
You can modify as below if you want the tokens separated by a comma:

    for (int i = 0; i < strArr.length; i++) {
        if (strArr[i] == null)
            break;
          //    System.out.println(strArr[i]);
        if(i!=0)
            sbResult.append(",");
        sbResult.append(strArr[i]);

    }
    System.out.println("sbResult: "+sbResult.toString());

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