Java implementation string inversion

There are several implementations for using the Java string inversion:

• Using the reverse function in the StringBuilder class;
• Using recursion, the first character of a string is placed after a substring other than the first character, and then the substring is called recursively;
• Use character arrays to do reverse;

public class Reverse {public static string reverse1 (String str) {if (str = = NULL | | str.length () <= 1) return Str;return New StringBuilder (str). reverse (). toString (); public static string Reverse2 (String str) {if (str = = NULL | | str.length () <= 1) return Str;return Reverse2 (Str.substrin G (1)) + str.charat (0);} public static string Reverse3 (String str) {if (str = = NULL | | str.length () <= 1) return str;char[] CA = new Char[str.len Gth ()];for (int i = 0; i < str.length (); i++) {Ca[i] = Str.charat (Str.length ()-i-1);} return new String (CA); public static void Main (string[] args) {String s = ' Hello World '; System.out.println (Reverse1 (s)); System.out.println (Reverse2 (s)); System.out.println (REVERSE3 (s));}}

Java implementation string inversion