style: apply checkstyle fixes and add checkstyle GHA workflow

Author: WhatDamon

.github/workflows/build.yml

@@ -23,3 +23,26 @@ jobs:
         with:
           name: Artifacts
           path: build/libs/
+
+  checkstyle:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v6
+      - name: Validate Gradle Wrapper
+        uses: gradle/actions/wrapper-validation@v4
+      - name: Setup JDK
+        uses: actions/setup-java@v5
+        with:
+          java-version: '25'
+          distribution: 'microsoft'
+      - name: Make Gradle Wrapper Executable
+        run: chmod +x ./gradlew
+      - name: Run Checkstyle
+        run: ./gradlew check
+      - name: Upload Checkstyle Report
+        uses: actions/upload-artifact@v6
+        if: always()
+        with:
+          name: checkstyle-report
+          path: build/reports/checkstyle/

src/main/java/org/damon233/performtrackermod/collector/SystemInfoCollector.java

@@ -152,7 +152,9 @@ private static String getWindowsCpuName() {
 
     private static String getLinuxCpuName() {
         String output = readFile("/proc/cpuinfo");
-        if (output == null) return "Unknown";
+        if (output == null) {
+            return "Unknown";
+        }
 
         for (String line : output.split("\n")) {
             line = line.trim();

src/main/java/org/damon233/performtrackermod/command/PtrackerCommand.java

@@ -191,14 +191,25 @@ public static void register() {
             LiteralArgumentBuilder<ServerCommandSource> config = CommandManager.literal("config");
             for (ConfigType cfg : ConfigType.values()) {
                 LiteralArgumentBuilder<ServerCommandSource> item = CommandManager.literal(cfg.key);
-                item.executes(ctx -> { cfg.sendInfo(ctx.getSource()); return 1; });
+                item.executes(ctx -> {
+                    cfg.sendInfo(ctx.getSource());
+                    return 1;
+                });
 
                 if (cfg.defaultValue instanceof Integer) {
                     item.then(CommandManager.argument("value", IntegerArgumentType.integer(1, 3600))
-                        .executes(ctx -> { cfg.setter.accept(IntegerArgumentType.getInteger(ctx, "value")); cfg.sendSuccess(ctx.getSource(), cfg.getter.get()); return 1; }));
+                        .executes(ctx -> {
+                            cfg.setter.accept(IntegerArgumentType.getInteger(ctx, "value"));
+                            cfg.sendSuccess(ctx.getSource(), cfg.getter.get());
+                            return 1;
+                        }));
                 } else if (cfg.defaultValue instanceof Boolean) {
                     item.then(CommandManager.argument("value", BoolArgumentType.bool())
-                        .executes(ctx -> { cfg.setter.accept(BoolArgumentType.getBool(ctx, "value")); cfg.sendSuccess(ctx.getSource(), cfg.getter.get()); return 1; }));
+                        .executes(ctx -> {
+                            cfg.setter.accept(BoolArgumentType.getBool(ctx, "value"));
+                            cfg.sendSuccess(ctx.getSource(), cfg.getter.get());
+                            return 1;
+                        }));
                 } else {
                     item.then(CommandManager.argument("value", StringArgumentType.string())
                         .executes(ctx -> {
@@ -220,7 +231,9 @@ public static void register() {
             }
             config.executes(ctx -> {
                 ctx.getSource().sendFeedback(() -> Text.literal("=== PerformTracker Config ==="), false);
-                for (ConfigType cfg : ConfigType.values()) cfg.sendLine(ctx.getSource());
+                for (ConfigType cfg : ConfigType.values()) {
+                    cfg.sendLine(ctx.getSource());
+                }
                 ctx.getSource().sendFeedback(() -> Text.literal("======================="), false);
                 ctx.getSource().sendFeedback(() -> Text.translatable("performtracker.config.usage"), false);
                 return 1;

src/main/java/org/damon233/performtrackermod/config/ConfigAccess.java

@@ -231,7 +231,9 @@ public static void setOutputFormat(String format) {
     }
 
     private static String normalizeOutputFormat(String format) {
-        if (format == null) return null;
+        if (format == null) {
+            return null;
+        }
         String lower = format.toLowerCase().trim();
         if (lower.equals("csv") || lower.equals("json") || lower.equals("yaml")) {
             return lower;

src/main/java/org/damon233/performtrackermod/controller/TrackerController.java

@@ -261,14 +261,18 @@ private MutableText buildChatMessage(PerformanceMetrics metrics) {
 
         MutableText result = Text.empty();
         for (int i = 0; i < chatMessagePartCount; i++) {
-            if (i > 0) result = result.append(Text.literal(" | ").withColor(0x888888));
+            if (i > 0) {
+                result = result.append(Text.literal(" | ").withColor(0x888888));
+            }
             result = result.append(chatMessageParts[i]);
         }
         return result;
     }
 
     private void addChatPart(String label, String value) {
-        if (chatMessagePartCount >= chatMessageParts.length) return;
+        if (chatMessagePartCount >= chatMessageParts.length) {
+            return;
+        }
         chatMessageParts[chatMessagePartCount++] = Text.literal(label).withColor(0x888888).append(TranslationService.colorValue(value));
     }
 

src/main/java/org/damon233/performtrackermod/data/PerformanceMetrics.java

@@ -34,7 +34,9 @@ public record PerformanceMetrics(
         mspt = Math.max(0.0, mspt);
         heapUsed = Math.max(0.0, heapUsed);
         heapMax = Math.max(0.0, heapMax);
-        if (cpuUsage < 0) cpuUsage = -1.0;
+        if (cpuUsage < 0) {
+            cpuUsage = -1.0;
+        }
     }
 
     public static String formatValue(double value) {

src/main/java/org/damon233/performtrackermod/network/JsonFormatter.java

@@ -37,23 +37,31 @@ public static String formatMetrics(long timestamp, String sessionId,
             first = false;
         }
         if (collectTps) {
-            if (!first) sb.append(',');
+            if (!first) {
+                sb.append(',');
+            }
             sb.append("\"tps\":").append(tps);
             first = false;
         }
         if (collectMspt) {
-            if (!first) sb.append(',');
+            if (!first) {
+                sb.append(',');
+            }
             sb.append("\"mspt\":").append(mspt);
             first = false;
         }
         if (collectHeap) {
-            if (!first) sb.append(',');
+            if (!first) {
+                sb.append(',');
+            }
             sb.append("\"heapUsed\":").append(heapUsed);
             sb.append(",\"heapMax\":").append(heapMax);
             first = false;
         }
         if (collectCpu) {
-            if (!first) sb.append(',');
+            if (!first) {
+                sb.append(',');
+            }
             sb.append("\"cpu\":").append(cpuUsage);
         }
         sb.append("}}");
@@ -62,7 +70,9 @@ public static String formatMetrics(long timestamp, String sessionId,
     }
 
     public static String escapeJson(String s) {
-        if (s == null) return "";
+        if (s == null) {
+            return "";
+        }
         return s.replace("\\", "\\\\")
                 .replace("\"", "\\\"")
                 .replace("\n", "\\n")

src/main/java/org/damon233/performtrackermod/utils/CharsetDetector.java

@@ -71,7 +71,9 @@ public static Charset detect() {
 
     private static Charset detectWindows() {
         String codepage = runCommand("chcp");
-        if (codepage == null) return null;
+        if (codepage == null) {
+            return null;
+        }
 
         try {
             String num = codepage.replaceAll("[^0-9]", "");
@@ -83,18 +85,20 @@ private static Charset detectWindows() {
     }
 
     private static Charset detectLinux() {
-        // Check LANG env var first (fast, no subprocess)
         String locale = System.getenv("LANG");
         Charset charset = parseLocaleToCharset(locale);
-        if (charset != null) return charset;
+        if (charset != null) {
+            return charset;
+        }
 
-        // Fallback to locale charmap command
         locale = runCommand("locale charmap");
         return parseLocaleToCharset(locale);
     }
 
     static Charset parseLocaleToCharset(String locale) {
-        if (locale == null) return null;
+        if (locale == null) {
+            return null;
+        }
 
         locale = locale.trim().toUpperCase();
         if (locale.contains("UTF-8") || locale.contains("UTF8")) {

src/main/java/org/damon233/performtrackermod/writer/CsvWriter.java

@@ -39,10 +39,14 @@ protected String getThreadName() {
 
     @Override
     public void writeHeader(String... headers) throws IOException {
-        if (headerWritten || writer == null) return;
+        if (headerWritten || writer == null) {
+            return;
+        }
 
         StringBuilder sb = new StringBuilder("unix_timestamp");
-        for (String h : headers) sb.append(",").append(h);
+        for (String h : headers) {
+            sb.append(",").append(h);
+        }
         writer.write(sb.toString());
         writer.newLine();
         headerWritten = true;

src/main/java/org/damon233/performtrackermod/writer/JsonWriter.java

@@ -88,8 +88,12 @@ protected void flushInternal() throws IOException {
 
     private Object formatValue(Object v) {
         if (v instanceof Double d) {
-            if (Double.isNaN(d)) return null;
-            if (Double.isInfinite(d)) return "infinite";
+            if (Double.isNaN(d)) {
+                return null;
+            }
+            if (Double.isInfinite(d)) {
+                return "infinite";
+            }
             return d;
         }
         return v;