CODEWITHSUNDEEP
javaregex
Laxmi Kadariya
Laxmi Kadariya

Reputation: 1103

what kind of string is split by the ^ regex

If I have split statement like 

String array1[]= test.split("^");

what could be the possible test string value such that this ("^") regex will split the test string?

I am aware that The ^ is a special character in Java regex - it means "match the beginning" of an input.

Upvotes: 0

Views: 54

Answers (2)

Jacob G.
Jacob G.

Reputation: 29680

what could be the possible test string value such that this ("^") regex will split the test string?

^ matches the beginning of a line in Java.

According to the Pattern documentation:

By default, the regular expressions ^ and $ ignore line terminators and only match at the beginning and the end, respectively, of the entire input sequence. If MULTILINE mode is activated then ^ matches at the beginning of input and after any line terminator except at the end of input. When in MULTILINE mode $ matches just before a line terminator or the end of the input sequence. (Emphasis, mine)

Therefore, the following code will produce the output below:

Pattern pattern = Pattern.compile("^", Pattern.MULTILINE);
System.out.println(Arrays.toString(pattern.split("Test\nTest")));

Output:

[Test
, Test]

As you can see, the String has been split successfully.

Upvotes: 4

PhaseRush
PhaseRush

Reputation: 350

I believe that this will not "split" any string, and instead just match the very first character of any string, making the array length 1 with only the original string inside.

This is the code I used for testing:

public static void main(String[] args) {
        List<String[]> allArrays = new ArrayList<>();

        String[] a1 = "afeafwewa".split("^");
        String[] a2 = "   fwaefawwa   ".split("^");
        String[] a3 = "fawef feawf a".split("^");
        String[] a4 = "L feawf :::".split("^");
        String[] a5 = "awefawefafewf     \\\\\\".split("^");
        String[] a6 = "\"".split("^");
        String[] a7 = "\\".split("^");

        allArrays.add(a1);
        allArrays.add(a2);
        allArrays.add(a3);
        allArrays.add(a4);
        allArrays.add(a5);
        allArrays.add(a6);
        allArrays.add(a7);

        allArrays.forEach(strings -> System.out.println(strings.length + " : " + strings[0]));
    }

Here is the output:

1 : afeafwewa
1 :    fwaefawwa   
1 : fawef feawf a
1 : L feawf :::
1 : awefawefafewf     \\\
1 : "
1 : \

This confirms that the entire string is matched, and that no splitting occurs.

Note: I have tested this with other strings as well, but I didn't paste them all in this code.

Upvotes: 0

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