Java Data Type - 如何交换字符串字符

public class Main {
  public static void main(String[] args) {
    System.out.println(swapChars("abcde", 0, 1));
  }

  private static String swapChars(String str, int lIdx, int rIdx) {
    StringBuilder sb = new StringBuilder(str);
    char l = sb.charAt(lIdx), r = sb.charAt(rIdx);
    sb.setCharAt(lIdx, r);
    sb.setCharAt(rIdx, l);
    return sb.toString();
  }
}