MapleEquipOnlyId.java

package client.inventory;

import database.DatabaseConnection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.concurrent.atomic.AtomicInteger;

public class MapleEquipOnlyId {

    private final AtomicInteger runningId;

    public static MapleEquipOnlyId getInstance() {
        return SingletonHolder.instance;
    }

    private MapleEquipOnlyId() {
        this.runningId = new AtomicInteger(0);
    }

    public int getNextEquipOnlyId() {
        if (this.runningId.get() <= 0) {
            this.runningId.set(initOnlyId());
        } else {
            this.runningId.set(this.runningId.get() + 1);
        }
        return this.runningId.get();
    }

    public int initOnlyId() {
        int ret = 0;

        try (PreparedStatement ps = DatabaseConnection.getConnection().prepareStatement("SELECT MAX(equipOnlyId) FROM inventoryitems WHERE equipOnlyId > 0"); ResultSet rs = ps.executeQuery()) {
            if (rs.next()) {
                ret = rs.getInt(1) + 1;
            }
            ps.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return ret;
    }

    private static class SingletonHolder {

        protected static final MapleEquipOnlyId instance = new MapleEquipOnlyId();
    }
}