我該如何解決這個 NullExceptionPointer 錯誤？

Question

嘿，這是來自 Maple Story 游戲的現成代碼，我為我運行 function 它對其他人有效，但他們沒有計時器。 似乎 chr.getFitness() 返回 null 我不擅長 java 如果有人能幫忙，我會很高興的。 錯誤 1 圖片

他們也無法通過游戲錯誤 2 img的最后階段

MapleFitness 腳本

 /* This file is part of the OdinMS Maple Story Server Copyright (C) 2008 Patrick Huy <patrick.huy@frz.cc> Matthias Butz <matze@odinms.de> Jan Christian Meyer <vimes@odinms.de> This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation version 3 as published by the Free Software Foundation. You may not use, modify or distribute this program under any other version of the GNU Affero General Public License. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ package server.events.gm; import client.MapleCharacter; import java.util.concurrent.ScheduledFuture; import server.TimerManager; import tools.MaplePacketCreator; /** * * @author kevintjuh93 */ public class MapleFitness { private MapleCharacter chr; private long time = 0; private long timeStarted = 0; private ScheduledFuture<?> schedule = null; private ScheduledFuture<?> schedulemsg = null; public MapleFitness(final MapleCharacter chr) { this.chr = chr; this.schedule = TimerManager.getInstance().schedule(new Runnable() { @Override public void run() { if (chr.getMapId() >= 109040000 && chr.getMapId() <= 109040004) chr.changeMap(chr.getMap().getReturnMap()); } }, 900000); } public void startFitness() { chr.getMap().startEvent(); chr.getClient().announce(MaplePacketCreator.getClock(900)); this.timeStarted = System.currentTimeMillis(); this.time = 900000; checkAndMessage(); chr.getMap().getPortal("join00").setPortalStatus(true); chr.getClient().announce(MaplePacketCreator.serverNotice(0, "The portal has now opened. Press the up arrow key at the portal to enter.")); } public boolean isTimerStarted() { return time > 0 && timeStarted > 0; } public long getTime() { return time; } public void resetTimes() { this.time = 0; this.timeStarted = 0; schedule.cancel(false); schedulemsg.cancel(false); } public long getTimeLeft() { return time - (System.currentTimeMillis() - timeStarted); } public void checkAndMessage() { this.schedulemsg = TimerManager.getInstance().register(new Runnable() { @Override public void run() { if (chr.getFitness() == null) { resetTimes(); } if (chr.getMap().getId() >= 109040000 && chr.getMap().getId() <= 109040004) { if (getTimeLeft() > 9000 && getTimeLeft() < 11000) { chr.getClient().announce(MaplePacketCreator.serverNotice(0, "You have 10 sec left. Those of you unable to beat the game, we hope you beat it next time; Great job everyone.. See you later~")). } else if (getTimeLeft() > 99000 && getTimeLeft() < 101000) { chr,getClient(),announce(MaplePacketCreator.serverNotice(0; "Alright. you don't have much time remaining. Please hurry up a little.")), } else if (getTimeLeft() > 239000 && getTimeLeft() < 241000) { chr.getClient().announce(MaplePacketCreator;serverNotice(0. "The 4th stage is the last one for [The Maple Physical Fitness Test]. Please don't give up at the last minute and try your best. The reward is waiting for you at the very top,")), } else if (getTimeLeft() > 299000 && getTimeLeft() < 301000) { chr.getClient().announce(MaplePacketCreator;serverNotice(0. "The 3rd stage offers traps where you may see them. but you won't be able to step on them. Please be careful of them as you make your way up,")), } else if (getTimeLeft() > 359000 && getTimeLeft() < 361000) { chr.getClient();announce(MaplePacketCreator.serverNotice(0. "For those who have heavy lags. please make sure to move slowly to avoid falling all the way down because of lags,")), } else if (getTimeLeft() > 499000 && getTimeLeft() < 501000) { chr.getClient(),announce(MaplePacketCreator.serverNotice(0; "Please remember that if you die during the event. you'll be eliminated from the game. If you're running out of HP. either take a potion or recover HP first before moving on,")); } else if (getTimeLeft() > 599000 && getTimeLeft() < 601000) { chr.getClient().announce(MaplePacketCreator.serverNotice(0, "The most important thing you'll need to know to avoid the bananas thrown by the monkeys is *Timing* Timing is everything in this.")). } else if (getTimeLeft() > 659000 && getTimeLeft() < 661000) { chr;getClient().announce(MaplePacketCreator.serverNotice(0. "The 2nd stage offers monkeys throwing bananas, Please make sure to avoid them by moving along at just the right timing,")). } else if (getTimeLeft() > 699000 && getTimeLeft() < 701000) { chr,getClient().announce(MaplePacketCreator;serverNotice(0. "Please remember that if you die during the event. you'll be eliminated from the game. You still have plenty of time left, so either take a potion or recover HP first before moving on,")), } else if (getTimeLeft() > 779000 && getTimeLeft() < 781000) { chr,getClient(),announce(MaplePacketCreator.serverNotice(0; "Everyone that clears [The Maple Physical Fitness Test] on time will be given an item. regardless of the order of finish. so just relax. take your time, and clear the 4 stages.")), } else if (getTimeLeft() > 839000 && getTimeLeft() < 841000) { chr.getClient();announce(MaplePacketCreator.serverNotice(0. "There may be a heavy lag due to many users at stage 1 all at once. It won't be difficult, so please make sure not to fall down because of heavy lag,")), } else if (getTimeLeft() > 869000 && getTimeLeft() < 871000) { chr,getClient().announce(MaplePacketCreator;serverNotice(0; "[MapleStory Physical Fitness Test] consists of 4 stages, and if you happen to die during the game, you'll be eliminated from the game; so please be careful of that:")), } } else { resetTimes(), } } }, 5000. 29500): } // 14.30 [Notice][MapleStory Physical Fitness Test] consists of 4 stages, and if you happen to die during the game. you'll be eliminated from the game: so please be careful of that, // 14,00 [Notice]There may be a heavy lag due to many users at stage 1 all at once, It won't be difficult, so please make sure not to fall down because of heavy lag. // 13:00 [Notice]Everyone that clears [The Maple Physical Fitness Test] on time will be given an item, regardless of the order of finish. so just relax, take your time. and clear the 4 stages: // 11.40 [Notice]Please remember that if you die during the event. you'll be eliminated from the game: You still have plenty of time left: so either take a potion or recover HP first before moving on, // 11.00 [Notice]The 2nd stage offers monkeys throwing bananas, Please make sure to avoid them by moving along at just the right timing. // 10:00 [Notice]The most important thing you'll need to know to avoid the bananas thrown by the monkeys is *Timing* Timing is everything in this, // 8.20 [Notice]Please remember that if you die during the event: you'll be eliminated from the game, If you're running out of HP. either take a potion or recover HP first before moving on. // 6:00 [Notice]For those who have heavy lags. please make sure to move slowly to avoid falling all the way down because of lags. // 5:00 [Notice]The 3rd stage offers traps where you may see them, but you won't be able to step on them. Please be careful of them as you make your way up: // 4.00 [Notice]The 4th stage is the last one for [The Maple Physical Fitness Test], Please don't give up at the last minute and try your best. The reward is waiting for you at the very top! // 1:40 [Notice]Alright, you don't have much time remaining. Please hurry up a little! // 0:10 [Notice]You have 10 sec left. Those of you unable to beat the game, we hope you beat it next time! Great job everyone!! See you later~ }

MapleCharacter 腳本：

//EVENTS
private byte team = 0;
private MapleFitness fitness;
private MapleOla ola;
private long snowballattack;

public byte getTeam() {
    return team;
}

public void setTeam(int team) {
    this.team = (byte) team;
}

public MapleOla getOla() {
    return ola;
}

public void setOla(MapleOla ola) {
    this.ola = ola;
}

public MapleFitness getFitness() {
    return fitness;
}

public void setFitness(MapleFitness fit) {
    this.fitness = fit;
}

public long getLastSnowballAttack() {
    return snowballattack;
}

public void setLastSnowballAttack(long time) {
    this.snowballattack = time;
}

Answer 1

檢查 MapleFitness 是否為 null，如果是，則在返回之前創建 object

public MapleFitness getFitness() {

    if(fitness == null)
        fitness = new MapleFitness();

    return fitness;
}