You can use replaceAll
with a regular expression that looks for the case where all three parts use the same digit:
static String getHex(int r, int g, int b) {
return String.format("#%02x%02x%02x", r, g, b).replaceAll("^#([a-fA-F])\1([a-fA-F])\2([a-fA-F])\3$", "#$1$2$3");
}
That looks for a string starting with #
followed by three pairs of matching hex digits, and replaces them with just the short form. (I suppose I could have just used [a-f]
instead of [a-fA-F]
in your specific example, since you know you'll be getting lower case only, but...)
Complete example (on Ideone):
public class Example {
public static void main(String[] args) {
System.out.println(getHex(255, 255, 255)); // #fff
System.out.println(getHex(255, 240, 255)); // #fff0ff
}
static String getHex(int r, int g, int b) {
return String.format("#%02x%02x%02x", r, g, b).replaceAll("^#([a-fA-F])\1([a-fA-F])\2([a-fA-F])\3$", "#$1$2$3");
}
}
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