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.
System.out.printf("Character %c is invalid.%n", codePoint); //recommended
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.
System.out.println("Character " + String.valueOf(char) + " is invalid."); //not recommended
