Using variables in chat messages

Plugins Plugin Development
1

Hi all,
I’m proficient with java and love minecraft, and thought that I might start looking into making plugins. It is cool, except I am not too sure on some of the minecraft interactions.
The ones that I am particularly stuck on are:

  1. How to assign a player input (from server chat) to a variable.
  2. How to display variables in outputs to server chat.

Any help is greatly appreciated.

2

I’m a bit confused about exactly what you want. Can you be more specific?

Is it something like this?

private Text myVariable;

@Listener
public void onChat(MessageChannelEvent.Chat event) {
	if(<your check here>) {
		myVariable = event.getMessage();
	}
}
	
public void printVariable(MessageChannel channel) {
	channel.send(myVariable);
}

The first method is a listener. It’s called whenever some specific thing happens. In this case that thing is that someone chats.

The second method takes a MessageChannel and sends the variable to that channel. A MessageChannel can be though of as a collection of MessageRecievers. A MessageReciever as it’s name implies is something that can receive messages.

You can read more about this on the docs;
https://docs.spongepowered.org/master/en/plugin/event/index.html
https://docs.spongepowered.org/master/en/plugin/text/messagechannels.html

3

Thanks, just on the second point, i want to print the variable along with fixed text.

4

Sponge will automatically give you a logger that you can use to log stuff. Just put this in your main plugin file.

@Inject
Logger logger;

https://docs.spongepowered.org/master/en/plugin/injection.html

5

Sorry, let me rephrase my question:

  1. What is the equivalent of the basic Scanner for sponge?
  2. How could I make an output to all players saying: “[initiator of command] has started a [string variable defined in previous command]”

Thanks.

6

@DankMemes This is entirely untested code, but feel to learn from it and/or tweak it to your needs.

import com.google.common.collect.Maps;
import com.google.inject.Inject;
import org.spongepowered.api.Game;
import org.spongepowered.api.command.CommandResult;
import org.spongepowered.api.command.args.GenericArguments;
import org.spongepowered.api.command.spec.CommandSpec;
import org.spongepowered.api.entity.living.player.Player;
import org.spongepowered.api.event.Listener;
import org.spongepowered.api.event.game.state.GameInitializationEvent;
import org.spongepowered.api.text.Text;

import javax.annotation.Nonnull;
import java.util.Map;
import java.util.Optional;
import java.util.UUID;

public class Test {

    @Nonnull private final Game game;
    @Nonnull private final Map<UUID, Map<String, String>> playerVariables;

    @Inject public Test(@Nonnull final Game game) {
        this.game = game;
        this.playerVariables = Maps.newHashMap();
    }

    @Listener public void onInit(@Nonnull final GameInitializationEvent event) {
        final CommandSpec keySetCommand = CommandSpec.builder()
                .description(Text.of("Set a value to a key!"))
                .permission("test.key.set")
                .arguments(
                        GenericArguments.onlyOne(GenericArguments.string(Text.of("key"))),
                        GenericArguments.remainingJoinedStrings(Text.of("value")))
                .executor((src, args) -> {
                    if (!(src instanceof Player)) {
                        src.sendMessage(Text.of("Only a player can assign a variable to themselves!"));
                        return CommandResult.success();
                    }

                    final Optional<String> key = args.getOne("key");
                    final Optional<String> value = args.getOne("value");

                    if (!key.isPresent() || !value.isPresent()) {
                        src.sendMessage(Text.of("This command requires both a key and a value!: /set <key> <value>"));
                        return CommandResult.success();
                    }

                    final UUID uuid = ((Player) src).getUniqueId();

                    if (!this.playerVariables.containsKey(uuid)) {
                        this.playerVariables.put(uuid, Maps.newHashMap());
                    }

                    this.playerVariables.get(uuid).put(key.get(), value.get()); // Check is already performed above

                    return CommandResult.success();
                })
                .build();

        final CommandSpec startKeyValue = CommandSpec.builder()
                .description(Text.of("Display value to everyone on the server!"))
                .permission("test.key.start")
                .arguments(GenericArguments.onlyOne(GenericArguments.string(Text.of("key"))))
                .executor((src, args) -> {
                    if (!(src instanceof Player)) {
                        src.sendMessage(Text.of("Only a player can send out a message!"));
                        return CommandResult.success();
                    }

                    final Optional<String> key = args.getOne("key");

                    if (!key.isPresent()) {
                        src.sendMessage(Text.of("This command requires a key! /start <key>"));
                        return CommandResult.success();
                    }

                    final UUID uuid = ((Player) src).getUniqueId();

                    if (this.playerVariables.get(uuid) == null) {
                        src.sendMessage(Text.of("You must first create a value for this key! /set <key> <value>"));
                        return CommandResult.success();
                    }

                    final String value = this.playerVariables.get(uuid).get(key.get());

                    if (value == null) {
                        src.sendMessage(Text.of("You must first create a value for this key! /set <key> <value>"));
                        return CommandResult.success();
                    }

                    for (final Player player : this.game.getServer().getOnlinePlayers()) {
                        player.sendMessage(Text.of(src.getName() + "has started " + value));
                    }

                    return CommandResult.success();
                })
                .build();

        this.game.getCommandManager().register(this, keySetCommand, "set");
        this.game.getCommandManager().register(this, startKeyValue, "start");
    }
}
7
  1. There isn’t an equivalent of Scanner. Sponge, like Bukkit, is an event-based system. Your interaction with the player’s chat is through events.
  2. game.getServer().getBroadcastChannel().send(message);
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