add checkstyle

Signed-off-by: Gregor Zeitlinger <[email protected]>

Author: zeitlinger

.editorconfig

@@ -2,3 +2,4 @@ root = true
 
 [*]
 max_line_length = 100
+indent_size = 2

checkstyle.xml

@@ -266,9 +266,7 @@
     </module>
     -->
     <module name="OverloadMethodsDeclarationOrder"/>
-    <!-- there are only a few violations of this, and they all appear to be for good reasons
     <module name="VariableDeclarationUsageDistance"/>
-    -->
     <module name="CustomImportOrder">
       <property name="sortImportsInGroupAlphabetically" value="true"/>
       <property name="separateLineBetweenGroups" value="true"/>

integration-tests/it-exporter/it-exporter-httpserver-sample/src/main/java/io/prometheus/metrics/it/exporter/httpserver/HTTPServerSample.java

@@ -26,7 +26,10 @@ public static void main(String[] args) throws IOException, InterruptedException
 
     int port = parsePortOrExit(args[0]);
     Mode mode = parseModeOrExit(args[1]);
+    run(mode, port);
+  }
 
+  private static void run(Mode mode, int port) throws IOException, InterruptedException {
     Counter counter =
         Counter.builder()
             .name("uptime_seconds_total")

prometheus-metrics-instrumentation-jvm/src/main/java/io/prometheus/metrics/instrumentation/jvm/JvmMemoryMetrics.java

@@ -309,11 +309,11 @@ public void register() {
     }
 
     public void register(PrometheusRegistry registry) {
-      MemoryMXBean memoryMXBean =
+      MemoryMXBean bean =
           this.memoryBean != null ? this.memoryBean : ManagementFactory.getMemoryMXBean();
       List<MemoryPoolMXBean> poolBeans =
           this.poolBeans != null ? this.poolBeans : ManagementFactory.getMemoryPoolMXBeans();
-      new JvmMemoryMetrics(poolBeans, memoryMXBean, config).register(registry);
+      new JvmMemoryMetrics(poolBeans, bean, config).register(registry);
     }
   }
 }

prometheus-metrics-instrumentation-jvm/src/main/java/io/prometheus/metrics/instrumentation/jvm/JvmMemoryPoolAllocationMetrics.java

@@ -56,7 +56,6 @@ private JvmMemoryPoolAllocationMetrics(List<GarbageCollectorMXBean> garbageColle
   }
 
   private void register(PrometheusRegistry registry) {
-
     Counter allocatedCounter =
         Counter.builder()
             .name(JVM_MEMORY_POOL_ALLOCATED_BYTES_TOTAL)
@@ -68,10 +67,9 @@ private void register(PrometheusRegistry registry) {
 
     AllocationCountingNotificationListener listener =
         new AllocationCountingNotificationListener(allocatedCounter);
-    for (GarbageCollectorMXBean garbageCollectorMXBean : garbageCollectorBeans) {
-      if (garbageCollectorMXBean instanceof NotificationEmitter) {
-        ((NotificationEmitter) garbageCollectorMXBean)
-            .addNotificationListener(listener, null, null);
+    for (GarbageCollectorMXBean bean : garbageCollectorBeans) {
+      if (bean instanceof NotificationEmitter) {
+        ((NotificationEmitter) bean).addNotificationListener(listener, null, null);
       }
     }
   }

prometheus-metrics-instrumentation-jvm/src/main/java/io/prometheus/metrics/instrumentation/jvm/JvmThreadsMetrics.java

@@ -149,7 +149,7 @@ private Map<String, Integer> getThreadStateCountMap(ThreadMXBean threadBean) {
       }
     }
 
-    int numberOfInvalidThreadIds = threadIds.length - writePos;
+    final int numberOfInvalidThreadIds = threadIds.length - writePos;
     threadIds = Arrays.copyOf(threadIds, writePos);
 
     // Get thread information without computing any stack traces