服务器急诊室

教学示意堆栈 并非本次实测日志 · 位置见本节说明

java.lang.NullPointerException: ...
    at de.teacherma.orerush.OreRushPlugin.onCommand(OreRushPlugin.java:58)
    at org.bukkit.command.PluginCommand.execute(PluginCommand.java:...)

写一张故障记录 · 位置见本节说明

步骤: 输入/orerush score
预期: 未报名提示
实际: 红字异常
环境: Java21 Paper1.21.11 插件版本与完整异常另附

可加入管理命令的安全片段 · 位置见本节说明

Player target = getServer().getPlayerExact(name);
if (target == null) {
    sender.sendMessage("玩家不在线，请检查名字");
    return true;
}
target.sendMessage("老师邀请你参加测试");

保留异常而不是装作成功 · 位置见本节说明

catch (IOException ex) {
    getLogger().log(Level.WARNING, "读取失败", ex);
}

坏版本 忘记状态 · 故意错误，先预测再修复

if (scores.containsKey(id)) scores.merge(id, points, Integer::sum);

修复后的入口 · 位置见本节说明

if (state == State.RUNNING && scores.containsKey(id) && points > 0)
    scores.computeIfPresent(id, (key, old) -> old + points);

能揭露问题的检查 · 位置见本节说明

r.add(alex, 10); // 在WAITING状态
check(r.snapshot().get(alex) == 0, "waiting cannot score");

坏版本 先判断后减数 · 故意错误，先预测再修复

if (remaining == 0) return true;
remaining--;
return false;

归零的那一次就结束 · 位置见本节说明

if (--remaining > 0) return false;
state = State.ENDING;
return true;

不把创建任务放在检查之前 · 位置见本节说明

if (!round.start(duration)) {
    sender.sendMessage("无法开始");
    return true;
}
// 下面才创建任务

清理要完整 · 完整文件

if (task != null) task.cancel();
task = null;
round.reset();
names.clear();

RoundChecks第1部分 · 顺序接在同一源文件

import de.teacherma.orerush.GameRound;
import java.util.UUID;

public class RoundChecks {
    private static int checks;
    private static void check(boolean condition, String name) {
        checks++;
        if (!condition) throw new AssertionError(name);
    }
    public static void main(String[] args) {
        UUID alex = new UUID(0, 1), steve = new UUID(0, 2);
        GameRound r = new GameRound();
        check(!r.start(60), "empty cannot start");
        check(r.join(alex), "first join");
        check(!r.join(alex), "duplicate join");
        r.add(alex, 10);
        check(r.snapshot().get(alex) == 0, "waiting cannot score");
        check(!r.start(0), "zero duration rejected");
        check(!r.start(3601), "too long rejected");
        check(r.start(2), "start two seconds");
        check(!r.start(2), "duplicate start rejected");
        check(!r.join(steve), "late join rejected");
        r.add(alex, 10); r.add(steve, 10); r.add(alex, -5);
        check(r.snapshot().get(alex) == 10, "valid points only");
        check(!r.snapshot().containsKey(steve), "outsider cannot score");

RoundChecks第2部分 · 顺序接在同一源文件

        check(!r.tick() && r.remaining() == 1, "first tick");
        check(r.tick(), "second tick ends");
        check(r.state() == GameRound.State.ENDING, "closed before result");
        r.add(alex, 10);
        check(r.snapshot().get(alex) == 10, "ending cannot score");
        check(!r.tick(), "cannot end twice");
        var result = r.snapshot();
        r.reset();
        check(r.state() == GameRound.State.WAITING, "reset state");
        check(r.snapshot().isEmpty(), "reset enrollment");
        check(result.get(alex) == 10, "snapshot survives reset");
        check(GameRound.points("DEEPSLATE_DIAMOND_ORE") == 10, "deep diamond");
        check(GameRound.points("GOLD_ORE") == 5, "gold");
        check(GameRound.points("DEEPSLATE_IRON_ORE") == 3, "deep iron");
        check(GameRound.points("STONE") == 0, "ordinary block");
        check(GameRound.points(null) == 0, "missing material");
        System.out.println("PASS " + checks + " checks");
    }
}

checks/sources.txt · 完整内容

src/main/java/de/teacherma/orerush/GameRound.java
checks/RoundChecks.java

Windows项目根目录运行 · 位置见本节说明

javac -encoding UTF-8 -d checks/out @checks/sources.txt
java -cp checks/out RoundChecks

运行结果

PASS 24 checks

只测一段纯计算 · 位置见本节说明

long started = System.nanoTime();
var result = round.snapshot();
long elapsedNs = System.nanoTime() - started;
// 单次结果受JVM预热等影响，不是正式性能结论。

有用但不过量的日志 · 位置见本节说明

getLogger().info("OreRush started, players=" + round.snapshot().size());