How can I split a string into an array in Java while preserving empty values?

General Discussions
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1

I need help using split() to split string into array java. Given the string:

String values = "0|0|0|1|||0|1|0|||";

I want to store the values in an array, where possible values are "0", "1", and "".

However, when I use:

String[] array = values.split("\\|");

The values are only saved until the last 0, and the "|||" at the end seems to be trimmed.

What am I doing wrong, and how can I ensure empty values are preserved?

2

Use split() with a Negative Limit

If you want to split string into array java and retain empty values, especially the trailing ones, pass -1 as the limit:

String values = "0|0|0|1|||0|1|0|||";
String[] array = values.split("\\|", -1);

:white_check_mark: Why it works:

Java’s split() trims trailing empty strings by default—but with -1 as the limit, it keeps all values, even if they’re empty.

So "|||" at the end doesn’t get lost; it turns into ["", "", ""] just as expected.

3

Use StringTokenizer for Detailed Handling

When you need to split string into array java and handle each delimiter more delicately, go for StringTokenizer:

import java.util.StringTokenizer;
import java.util.ArrayList;
import java.util.List;

String values = "0|0|0|1|||0|1|0|||";
StringTokenizer tokenizer = new StringTokenizer(values, "|", true);
List<String> result = new ArrayList<>();

boolean lastWasDelimiter = false;
while (tokenizer.hasMoreTokens()) {
    String token = tokenizer.nextToken();
    if (token.equals("|")) {
        if (lastWasDelimiter) result.add("");
        lastWasDelimiter = true;
    } else {
        result.add(token);
        lastWasDelimiter = false;
    }
}

String[] array = result.toArray(new String[0]);

:white_check_mark: Why this rocks:

  • Retains empty values between and around delimiters
  • Lets you build exactly the structure you want, with full control over parsing logic
4

Manually Append Missing Values When Needed

If you split string into array java using the regular split("\\|"), but find it trims too much, try this hybrid approach:

String[] array = values.split("\\|", -1);
if (values.endsWith("|")) {
    int expectedSize = values.split("\\|").length + 1;
    array = Arrays.copyOf(array, expectedSize);
}

:white_check_mark: Why bother?

  • It keeps the syntax familiar
  • You still get those trailing empty values without overhauling the code
  • Great workaround when you’re dealing with legacy methods or restricted APIs