Java.lang.NullPointerException錯誤

Question

我試圖運行遊戲RuneScape的私人服務器。一段時間後，我的一個玩家去了我在服務器pestcontrol中編程的迷你遊戲。玩家試圖加入它，但爲了能夠啓動它，他需要5個其他玩家才能工作。所以，他退出了。但之後，他的帳戶被清除，導致其他人也無效。我已經設法解決這個問題。但後來他看不見了，我看不到他的角色在遊戲中。 所以後來我工作了通過聲明如下：

if (player == null) 
return; 

該做的工作，使他再次可見。 但隨後仍然出現錯誤這一行的異常：

java.lang.NullPointerException 
at net.kagani.game.player.controllers.pestcontrol.PestControlLobby.forceClose(PestControlLobby.java:52) 
at net.kagani.game.player.ControlerManager.forceStop(ControlerManager.java:317) 
at net.kagani.game.player.ControlerManager.login(ControlerManager.java:66) 
at net.kagani.game.player.Player.sendInit(Player.java:1396) 
at net.kagani.game.player.Player.run(Player.java:1233) 
at net.kagani.game.player.Player.start(Player.java:886) 
at net.kagani.executor.PlayerHandlerThread.initPlayer(PlayerHandlerThread.java:273) 
at net.kagani.executor.PlayerHandlerThread.processLoginSession(PlayerHandlerThread.java:231) 
at net.kagani.executor.PlayerHandlerThread.run(PlayerHandlerThread.java:65) 

如果有人可以幫助我這個（重定向我給它）因爲我很願意學習了很多東西。 這是類本身：

package net.kagani.game.player.controllers.pestcontrol; 

import net.kagani.Settings; 
import net.kagani.game.WorldObject; 
import net.kagani.game.minigames.pest.Lander; 
import net.kagani.game.player.controllers.Controller; 
import net.kagani.utils.Utils; 

public final class PestControlLobby extends Controller { 
    private Lander lander; 

    @Override 
    public void start() { 
     this.lander = Lander.getLanders()[(Integer) getArguments()[0]]; 
    } 

    @Override 
    public void sendInterfaces() { 
     if (player == null) 
      return; 
     int remainingTime = lander.getTimer().getMinutes(); 
     player.getPackets().sendIComponentText(407, 3, 
       Utils.fixChatMessage(lander.toString())); 
     player.getPackets().sendIComponentText(
       407, 
       13, 
       "Next Departure: " + remainingTime + " minutes " 
         + (!(remainingTime % 2 == 0) ? " 30 seconds" : "")); 
     player.getPackets().sendIComponentText(407, 14, 
       "Player's Ready: " + lander.getByStanders().size()); 
     player.getPackets().sendIComponentText(407, 16, 
       "Commendations: " + player.getCommendation()); 
     player.getInterfaceManager().sendMinigameInterface(407); 
    } 

    @Override 
    public void magicTeleported(int teleType) { 
     player.getControlerManager().forceStop(); 
    } 

    @Override 
    public boolean sendDeath() { 
     player.getControlerManager().forceStop(); 
     return true; 
    } 

    @Override 
    public void forceClose() { 

     player.getInterfaceManager().removeMinigameInterface(); 
     System.err.println("This is 1 error output that declares it here"); 
     lander.exit(player); 
    } 

    @Override 
    public boolean logout() { 
     lander.remove(player); 
     return false; 
    } 

    @Override 
    public boolean canSummonFamiliar() { 
     player.getPackets() 
       .sendGameMessage(
         "You feel it's best to keep your Familiar away during this game."); 
     return false; 
    } 

    @Override 
    public boolean processObjectClick1(WorldObject object) { 
     switch (object.getId()) { 
      case 14314: 
      case 25629: 
      case 25630: 
       player.getDialogueManager().startDialogue("LanderD"); 
       return true; 
     } 
     return true; 
    } 
} 

Answer 1

player.getInterfaceManager（）尚未初始化，因此你要試圖縮小與forceClose遊戲（看你的堆棧跟蹤的第二行），當一個NullPointerException 。

我會建議將player.getInterfaceManager（）放在一個空檢查暫時，然後工作爲什麼這是null，當你認爲它將被訪問。

我建議閱讀更多關於如何讀取堆棧痕跡，所以這樣的事情，你可以馬上拿起。