Sample Usage

This page contains some code snippets that show you several commono scenarios.

Creating a String from a Code Point

String newString(int codePoint) {
    return new String(Character.toChars(codePoint));
}

Creating a String from a Code Point - Optimized for BMP Characters

The Character.toChars method creates an temporary array that is used once and then discarded. If this negatively affects performance, you can use the following approach that is optimizied for BMP characters (characters that are represented by a single char value). In this method, toChars is invoked only for supplementary characters.

String newString(int codePoint) {
    if (Character.charCount(codePoint) == 1) {
        return String.valueOf(codePoint);
    } else {
        return new String(Character.toChars(codePoint));
    }
}

Creating String Objects in Bulk

To create a large number of strings, the bulk version of the previous snippet reuses the array used by the toChars method. This method creates a separate String instance for each code point and is optimized for BMP characters.

String[] newStrings(int[] codePoints) {
    String[] result = new
        String[codePoints.length];
    char[] codeUnits = new char[2];
    for (int i = 0; i < codePoints.length; i++) {
        int count = Character.toChars(
            codePoints[i], codeUnits, 0);
        result[i] = new String(
            codeUnits, 0, count);
    }
    return result;
}

Generating Messages

The formatting API supports supplementary characters. The following example is a simple way to generate a message.

// recommended
System.out.printf(
    "Character %c is invalid.%n", codePoint);

This following approach is simple and avoids concatenation, which makes the text more difficult to localize as not all languages insert numeric values into a string in the same order as English.

// not recommended
System.out.println("Character " +
    String.valueOf(char) + " is invalid.");