Can anyone explain me why if I call a method in the same class my code works, but if I create a method in another class it won't work? Here an example with my code: In the same class, called Token.java Spoiler Code (Text): private static Main plugin; public Token(Main pl) { plugin = pl; } /* some code */ if(Integer.parseInt(args[2])>0){ try { balance = this.getBalance(p.getName()); } catch (SQLException e1) { e1.printStackTrace(); } if(balance > Integer.parseInt(args[2])){ try { this.removeTokens(p.getName(), Integer.parseInt(args[2])); p.sendMessage(ChatColor.GREEN + "Sent " + ChatColor.GRAY + args[2] + " Tokens to " + ChatColor.GRAY + args[1]); this.addTokens(args[1],Integer.parseInt(args[2])); Player p2 = plugin.getServer().getPlayer(args[1]); p2.sendMessage(ChatColor.GRAY + args[2] + ChatColor.GREEN + " Tokens has been sent by " + ChatColor.GRAY + p.getName()); } catch (NumberFormatException e) { p.sendMessage(ChatColor.RED + "Usage: /token pay <player> <tokens>"); } catch (SQLException e) { p.sendMessage(ChatColor.RED + "An error occurred. Contact an Admin to fix this."); } } else{ p.sendMessage(ChatColor.RED + "You do not have enough Tokens."); return false; } } And this is my method (it is in the same class, Token.java) PLEASE DO NOT COMMENT THE "USELESS" CODE, I KNOW THAT I HAVE TO RE-WRITE IT. Spoiler Code (Text): public int getBalance(String username) throws SQLException{ if(conn==null){ conn = plugin.connect(); } ps = conn.prepareStatement("SELECT balance FROM PlayersData WHERE username = ?"); ps.setString(1, username); ResultSet rs = ps.executeQuery(); if(rs.next()){ balance = rs.getInt("balance"); } rs.close(); return balance; } public void addTokens(String username, int tokens)throws SQLException{ if(conn==null){ conn = plugin.connect(); } balance = this.getBalance(username); balance = balance + tokens; ps = conn.prepareStatement("UPDATE PlayersData SET balance = ? WHERE username = ?"); ps.setInt(1, balance); ps.setString(2, username); ps.executeUpdate(); } public void removeTokens(String username, int tokens)throws SQLException{ if(conn==null){ conn = plugin.connect(); } balance = this.getBalance(username); balance = balance - tokens; ps = conn.prepareStatement("UPDATE PlayersData SET balance = ? WHERE username = ?"); ps.setInt(1, balance); ps.setString(2, username); ps.executeUpdate(); } This code will work... but if I create another class called TokenHandler.java in another package called Handlers and I write the addTokens, getBalance and removeTokens in this class, the first code won't work. Example: TokenHandler.java Spoiler Code (Text): //plugin is the instance of Main class //but I'm not sure on HOW to instantiate it in this class... public int getBalance(String username) throws SQLException{ if(conn==null){ conn = plugin.connect(); } ps = conn.prepareStatement("SELECT balance FROM PlayersData WHERE username = ?"); ps.setString(1, username); ResultSet rs = ps.executeQuery(); if(rs.next()){ balance = rs.getInt("balance"); } rs.close(); return balance; } public void addTokens(String username, int tokens)throws SQLException{ if(conn==null){ conn = plugin.connect(); } balance = this.getBalance(username); balance = balance + tokens; ps = conn.prepareStatement("UPDATE PlayersData SET balance = ? WHERE username = ?"); ps.setInt(1, balance); ps.setString(2, username); ps.executeUpdate(); } public void removeTokens(String username, int tokens)throws SQLException{ if(conn==null){ conn = plugin.connect(); } balance = this.getBalance(username); balance = balance - tokens; ps = conn.prepareStatement("UPDATE PlayersData SET balance = ? WHERE username = ?"); ps.setInt(1, balance); ps.setString(2, username); ps.executeUpdate(); } And this is my Token.java class Spoiler Code (Text): private static Main plugin; private static TokenHandler instance = new TokenHandler(); public Token(Main pl) { plugin = pl; } /* some code */ if(Integer.parseInt(args[2])>0){ try { balance = instance.getBalance(p.getName()); } catch (SQLException e1) { e1.printStackTrace(); } if(balance > Integer.parseInt(args[2])){ try { instance.removeTokens(p.getName(), Integer.parseInt(args[2])); p.sendMessage(ChatColor.GREEN + "Sent " + ChatColor.GRAY + args[2] + " Tokens to " + ChatColor.GRAY + args[1]); instance.addTokens(args[1],Integer.parseInt(args[2])); Player p2 = plugin.getServer().getPlayer(args[1]); p2.sendMessage(ChatColor.GRAY + args[2] + ChatColor.GREEN + " Tokens has been sent by " + ChatColor.GRAY + p.getName()); } catch (NumberFormatException e) { p.sendMessage(ChatColor.RED + "Usage: /token pay <player> <tokens>"); } catch (SQLException e) { p.sendMessage(ChatColor.RED + "An error occurred. Contact an Admin to fix this."); } } else{ p.sendMessage(ChatColor.RED + "You do not have enough Tokens."); return false; } }
What you have to do it use getters, setters and constructors. For example: In your main class define all your plugins e.g. private MainClass plugin; private MethodClass methods; then set the instance of your main claass variable in on enable with plugin = this; then you can do the same with the other variables e.g. methods = new Methods(this); then you would create a getter in your main class still outside everything else e.g. public MethodClass getMethods(){ return methods; } Then you would create a constructor in your methods class e.g. private final MainClass plugin; public MethodClass(MainClass plugin){ this.plugin = plugin; } Then from any class you can use e.g. plugin.getMethods().methodName; ps refrain from using static instances because i quote from a friend "Java is an Object-Oriented-Programming language (OOP) and typically when someone has all of their code filled with static methods, one can assume he/she is a lazy developer that doesn't really know what he/she is doing."
hmmm someone told me that there's an error if you did Code (Java): public int i() { return 0; } you have to put some space Code (Java): public int i () { return 0; } correct me if I'm mistaken
Java is entirely OOP, which is very annoying if you are (i assume?) coming from non-OOP languages like C, or simpler C++ Every file in java represents at least one object, there is no such thing as code that is not a class object, everything has to be instantiated, including your main class (bukkit does this for you).
Correct me if I'm wrong but C++ is (in a way) object oriented as it's considered a "multi-paradigm" language.
You are completely correct. It gives the option of writing procedural or OOP code, or combining the two. Honestly a combination of the two is much more efficient and easy to use than being forced entirely into OOP (it overcomplicates, not everything needs a class).
