in some of my code, i am having the error: The preview feature Implicitly Declared Classes and Instance Main Methods is only available with source level 22 and above, which is strange as i only installed java about a week ago and its on about version 17, im using vscode which has supported java for me so far, but after some point of coding one of my classess it has just malfunctioned, my code is here but im not sure if it will be of muc use to anyone:

import java.util.ArrayList;

public class An {
  String whichA(String text) {
    ArrayList<String> anLetters = new ArrayList<>();
    anLetters.add("a");
    anLetters.add("e");
    anLetters.add("i");
    anLetters.add("o");
    anLetters.add("u");
    Character c0 = text.charAt(0);
    Character c1 = text.charAt(1);
    if ((anLetters.contains(c0.toString().toLowerCase())) || (c0.toString() + c1.toString() == "11")){
      return "an";
    }
    else{
      return "a";
    }
  }

  String whichA(Integer number) {
    ArrayList<String> anLetters = new ArrayList<>();
    anLetters.add("a");
    anLetters.add("e");
    anLetters.add("i");
    anLetters.add("o");
    anLetters.add("u");
    String text = number.toString();
    Character c0 = text.charAt(0);
    Character c1 = text.charAt(1);
    if ((anLetters.contains(c0.toString().toLowerCase())) || (c0.toString() + c1.toString() == "11")){
      return "an";
    }
    else{
      return "a";
    }
  }

  String whichA(Long number) {
    ArrayList<String> anLetters = new ArrayList<>();
    anLetters.add("a");
    anLetters.add("e");
    anLetters.add("i");
    anLetters.add("o");
    anLetters.add("u");
    String text = number.toString();
    Character c0 = text.charAt(0);
    Character c1 = text.charAt(1);
    if ((anLetters.contains(c0.toString().toLowerCase())) || (c0.toString() + c1.toString() == "11")){
      return "an";
    }
    else{
      return "a";
    }
  }

  String whichA(Double number) {
    ArrayList<String> anLetters = new ArrayList<>();
    anLetters.add("a");
    anLetters.add("e");
    anLetters.add("i");
    anLetters.add("o");
    anLetters.add("u");
    String text = number.toString();
    Character c0 = text.charAt(0);
    Character c1 = text.charAt(1);
    if ((anLetters.contains(c0.toString().toLowerCase())) || (c0.toString() + c1.toString() == "11")){
      return "an";
    }
    else{
      return "a";
    }
  }

  String whichA(Float number) {
    ArrayList<String> anLetters = new ArrayList<>();
    anLetters.add("a");
    anLetters.add("e");
    anLetters.add("i");
    anLetters.add("o");
    anLetters.add("u");
    String text = number.toString();
    Character c0 = text.charAt(0);
    Character c1 = text.charAt(1);
    if ((anLetters.contains(c0.toString().toLowerCase())) || (c0.toString() + c1.toString() == "11")){
      return "an";
    }
    else{
      return "a";
    }
  }
  String whichTh(int num) {
    String suffix;
    num = num % 10;
    switch (num) {
      case 1: suffix = "st";
        break;
      case 2: suffix = "nd";
        break;
      case 3: suffix = "rd";
        break;
      default: suffix = "th";
        break;
    }
    return suffix;
  }

  String whichTh(long number) {
    String suffix;
    int num = (int) (number % 10);
    switch (num) {
      case 1: suffix = "st";
        break;
      case 2: suffix = "nd";
        break;
      case 3: suffix = "rd";
        break;
      default: suffix = "th";
        break;
    }
    return suffix;
  }

  String whichTh(float number) {
    String suffix;
    int num = (int) (number % 10);
    switch (num) {
      case 1: suffix = "st";
        break;
      case 2: suffix = "nd";
        break;
      case 3: suffix = "rd";
        break;
      default: suffix = "th";
        break;
    }
    return suffix;
  }

  String whichTh(double number) {
    String suffix;
    int num = (int) (number % 10);
    switch (num) {
      case 1: suffix = "st";
        break;
      case 2: suffix = "nd";
        break;
      case 3: suffix = "rd";
        break;
      default: suffix = "th";
        break;
    }
    return suffix;
  }

  String whichTh(String number) {
    String suffix;
    int num = Integer.parseInt(number) % 10;
    switch (num) {
      case 1: suffix = "st";
        break;
      case 2: suffix = "nd";
        break;
      case 3: suffix = "rd";
        break;
      default: suffix = "th";
        break;
    }
    return suffix;
  }
}

  String convertString(Integer variable){
    return variable.toString();
  }
  String convertString(Long variable){
    return variable.toString();
  }
  String convertString(Double variable){
    return variable.toString();
  }
  String convertString(Float variable){
    return variable.toString();
  }

  int convertInt(String variable) {
    return Integer.parseInt(variable);
  }

  int convertInt(long variable) {
    return (int) variable;
  }

  int convertInt(float variable) {
    return (int) variable;
  }

  int convertInt(double variable) {
    return (int) variable;
  }

  long convertLong(String variable){
    int number = Integer.parseInt(variable);
    return (long) number;
  }

  long convertLong(int variable){
    return (long) variable;
  }

  long convertLong(float variable){
    return (long) variable;
  }

  long convertLong(double variable){
    return (long) variable;
  }

  float convertFloat(String variable){
    int number = Integer.parseInt(variable);
    return (float) number;
  }

  float convertFloat(int variable) {
    return (float) variable;
  }

  float convertFloat(long variable) {
    return (float) variable;
  }

  float convertFloat(double variable) {
    return (float) variable;
  }

  double convertDouble(String variable) {
    int number = Integer.parseInt(variable);
    return (double) number;
  }

  double convertDouble(int variable) {
    return (double) variable;
  }

  double convertDouble(long variable) {
    return (double) variable;
  }

  double convertDouble(float variable) {
    return (double) variable;
  }

I was just doing some oop as i’m new to java and coming from python so its been w=quite an adjustmen, but all this object is meant to do is help with some stuf like knowing whether to but a or an before a word, whether to ad st, nd, rd, or th after a number, and converting data types. On vscode the error appears at the very start, does anyone know how i could update java (i used the vscode JavaCodingPack-0.4.1.exe for the java installation), any other solutions or whetheri should just use something like eclipse (ideally i would like to stick using vscode as i use multiple other programing languages/markup languages/stylers (python, html, css, javascript, and i hope to learn some others like C# in the future).