Use isEmpty() instead of "size() == 0" (#1151)

isEmpty() expresses the intent more clearly and is therefore preferred.
Counting the number of elements can also be an expensive operation e.g. when using linked lists.

Signed-off-by: Wouter Born <github@maindrain.net>

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/RuleEngineImpl.java

@@ -1140,7 +1140,7 @@ public class RuleEngineImpl implements RuleManager, RegistryChangeListener<Modul
      */
     private boolean calculateConditions(WrappedRule rule) {
         List<WrappedCondition> conditions = rule.getConditions();
-        if (conditions.size() == 0) {
+        if (conditions.isEmpty()) {
             return true;
         }
         final String ruleUID = rule.getUID();
@@ -1171,7 +1171,7 @@ public class RuleEngineImpl implements RuleManager, RegistryChangeListener<Modul
     private void executeActions(WrappedRule rule, boolean stopOnFirstFail) {
         final String ruleUID = rule.getUID();
         final Collection<WrappedAction> actions = rule.getActions();
-        if (actions.size() == 0) {
+        if (actions.isEmpty()) {
             return;
         }
         RuleStatus ruleStatus = null;

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/commands/Printer.java

@@ -537,7 +537,7 @@ public class Printer {
      * @return a formated string, representing the set of {@link Input}s or {@link Output}s or {@link Input}s.
      */
     private static String getTagsRecord(Set<String> tags) {
-        if (tags == null || tags.size() == 0) {
+        if (tags == null || tags.isEmpty()) {
             return "[ ]";
         }
         StringBuilder res = new StringBuilder().append("[ ");

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/provider/file/WatchServiceUtil.java

@@ -50,7 +50,7 @@ public class WatchServiceUtil {
         synchronized (WATCH_SERVICES) {
             Map<String, AutomationWatchService> watchers = WATCH_SERVICES.get(provider);
             aws = watchers.remove(watchingDir);
-            if (watchers.size() == 0) {
+            if (watchers.isEmpty()) {
                 WATCH_SERVICES.remove(provider);
             }
         }

bundles/org.openhab.core.compat1x/src/main/java/org/openhab/core/binding/AbstractActiveBinding.java

@@ -55,7 +55,7 @@ public abstract class AbstractActiveBinding<P extends BindingProvider> extends A
 
         // if there are no binding providers there is no need to run this
         // refresh thread any longer ...
-        if (this.providers.size() == 0) {
+        if (this.providers.isEmpty()) {
             activeService.deactivate();
         }
     }

bundles/org.openhab.core.config.core/src/main/java/org/eclipse/smarthome/config/core/ConfigUtil.java

@@ -146,7 +146,7 @@ public class ConfigUtil {
      * @throws IllegalArgumentException if the type of the normalized values differ or an invalid type has been given
      */
     private static Collection<Object> normalizeCollection(Collection<?> collection) throws IllegalArgumentException {
-        if (collection.size() == 0) {
+        if (collection.isEmpty()) {
             return Collections.emptyList();
         } else {
             final List<Object> lst = new ArrayList<>(collection.size());

bundles/org.openhab.core.io.rest.core/src/main/java/org/eclipse/smarthome/io/rest/core/internal/profile/ProfileTypeResource.java

@@ -120,7 +120,7 @@ public class ProfileTypeResource implements RESTResource {
 
     private boolean profileTypeMatchesItemType(ProfileType pt, String itemType) {
         Collection<String> supportedItemTypesOnProfileType = pt.getSupportedItemTypes();
-        if (supportedItemTypesOnProfileType.size() == 0
+        if (supportedItemTypesOnProfileType.isEmpty()
                 || supportedItemTypesOnProfileType.contains(ItemUtil.getMainItemType(itemType))
                 || supportedItemTypesOnProfileType.contains(itemType)) {
             return true;
@@ -132,7 +132,7 @@ public class ProfileTypeResource implements RESTResource {
         if (profileType instanceof TriggerProfileType) {
             TriggerProfileType triggerProfileType = (TriggerProfileType) profileType;
 
-            if (triggerProfileType.getSupportedChannelTypeUIDs().size() == 0) {
+            if (triggerProfileType.getSupportedChannelTypeUIDs().isEmpty()) {
                 return true;
             }
 
@@ -147,7 +147,7 @@ public class ProfileTypeResource implements RESTResource {
         if (profileType instanceof StateProfileType) {
             StateProfileType stateProfileType = (StateProfileType) profileType;
 
-            if (stateProfileType.getSupportedItemTypesOfChannel().size() == 0) {
+            if (stateProfileType.getSupportedItemTypesOfChannel().isEmpty()) {
                 return true;
             }
 

bundles/org.openhab.core.ui/src/main/java/org/eclipse/smarthome/ui/internal/chart/defaultchartprovider/DefaultChartProvider.java

@@ -372,7 +372,7 @@ public class DefaultChartProvider implements ChartProvider {
 
         // Add the new series to the chart - only if there's data elements to display
         // The chart engine will throw an exception if there's no data
-        if (xData.size() == 0) {
+        if (xData.isEmpty()) {
             return false;
         }
 

bundles/org.openhab.core.ui/src/main/java/org/eclipse/smarthome/ui/internal/items/ItemUIRegistryImpl.java

@@ -623,7 +623,7 @@ public class ItemUIRegistryImpl implements ItemUIRegistry {
             }
         } else if (w instanceof Switch) {
             Switch sw = (Switch) w;
-            if (sw.getMappings().size() == 0) {
+            if (sw.getMappings().isEmpty()) {
                 returnState = itemState.as(OnOffType.class);
             }
         }
@@ -1084,7 +1084,7 @@ public class ItemUIRegistryImpl implements ItemUIRegistry {
         if (colorList == null) {
             return null;
         }
-        if (colorList.size() == 0) {
+        if (colorList.isEmpty()) {
             return null;
         }
 
@@ -1167,7 +1167,7 @@ public class ItemUIRegistryImpl implements ItemUIRegistry {
         if (ruleList == null) {
             return true;
         }
-        if (ruleList.size() == 0) {
+        if (ruleList.isEmpty()) {
             return true;
         }
 

bundles/org.openhab.core.voice/src/main/java/org/eclipse/smarthome/core/voice/text/ExpressionCardinality.java

@@ -58,7 +58,7 @@ public final class ExpressionCardinality extends Expression {
                 break;
             }
         }
-        if (!(atLeastOne && nodes.size() == 0)) {
+        if (!(atLeastOne && nodes.isEmpty())) {
             node.setChildren(nodes.toArray(new ASTNode[0]));
             node.setRemainingTokens(list);
             node.setSuccess(true);