Split String with multiple continuous comma in Java [duplicate]

Question

String abc = "a,b,c,d,,,";
String[] arr = abc.split(",");
System.out.println(arr.length);

Output is 4. But obviously my expectation is 7. Here is my solution:

String abc = "a,b,c,d,,,";
abc += "\n";
String[] arr = abc.split(",");
System.out.println(arr.length);

Why does it happen? Anyone could give my a better solution?

Answer 1

Use the alternative version of String#split() that takes two arguments to achieve this:

String abc = "a,b,c,d,,,";
String[] arr = abc.split(",", -1);
System.out.println(arr.length);

This prints

7

From the Javadoc linked above:

If n is non-positive then the pattern will be applied as many times as possible and the array can have any length. If n is zero then the pattern will be applied as many times as possible, the array can have any length, and trailing empty strings will be discarded.

Answer 2

You can use lookahead:

String abc = "a,b,c,d,,,";
String[] arr = abc.split("(?=,)");
System.out.println(arr.length); //7

Answer 3

Use:

String[] arr = abc.split("(?=,)");

to split abc