toCharArray
followed by Arrays.sort
followed by a String constructor call:
import java.util.Arrays;
public class Test
{
public static void main(String[] args)
{
String original = "edcba";
char[] chars = original.toCharArray();
Arrays.sort(chars);
String sorted = new String(chars);
System.out.println(sorted);
}
}
EDIT: As tackline points out, this will fail if the string contains surrogate pairs or indeed composite characters (accent + e as separate chars) etc. At that point it gets a lot harder... hopefully you don't need this :) In addition, this is just ordering by ordinal, without taking capitalisation, accents or anything else into account.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…