Spliting string by character, returning with null values

Naman Gala

I have below code

String str= new String("aaa,,bbb,,ccc,");
String[] strArray= str.split(",");

From this I am getting below values in strArray

strArray = [aaa,'',bbb,'',ccc];

But I want below output

strArray = [aaa,null,bbb,null,ccc,null];

I have written my own function to do this, but I want to know is there any standard method which can give this output?

If yes then please suggest

If no then please suggest if any improvement for below code.

public List<String> splitStr(String str, char character) {
    List<String> list = null;
    if (StringUtil.isNotEmpty(str)) {
        list = new ArrayList<String>();
        int i;
        char ch;
        int characterIndex, loopStartingIndex = 0;

        if (str.charAt(0) == character) {
            list.add(null);
        } else {
            list.add(str.substring(0, str.indexOf(character)));
            loopStartingIndex = str.indexOf(character);
        }

        int length = str.length();
        for (i = loopStartingIndex; i < length; i++) {
            ch = str.charAt(i);
            if (ch == character) {
                characterIndex = str.indexOf(character, i+1);
                if (characterIndex == i+1 || characterIndex == -1) {
                    list.add(null);
                } else {
                    list.add(str.substring(i+1, characterIndex));
                    i = characterIndex-1;
                }
            }
        }
    }
    /*for (String s : list) {
        System.out.println(s);
    }*/

    return list;
}

Edit:

I had tested the code for abc,,,, string with str.split(",") method and I got [abc] as output so I thought aaa,,bbb,,ccc will give me 3 values by split method. But it is giving [aaa,'',bbb,'',ccc] skipping ending commas.

Elliott Frisch

You can pass a negative value to String.split(String, int) like

String str = "aaa,,bbb,,ccc,";
String[] strArray = str.split(",", -1);
System.out.println(Arrays.toString(strArray));

Output is

[aaa, , bbb, , ccc, ]

This is helpfully documented in the linked javadoc as,

If n is non-positive then the pattern will be applied as many times as possible and the array can have any length

Edit

public static void main(String[] args) {
    String str = "aaa,,bbb,,ccc,";
    String[] strArray = str.split(",", -1);
    for (int i = 0; i < strArray.length; i++) {
        if (strArray[i].isEmpty()) {
            strArray[i] = null;
        }
    }
    System.out.println(Arrays.toString(strArray));
}

Output is

[aaa, null, bbb, null, ccc, null]

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