Condition: avoid danger of JVM-level deadlock during initialisation

CHANGELOG

@@ -4,6 +4,7 @@ CHANGELOG
 0.3.0
 -----
 
+* Avoid danger of JVM-level deadlock during `Condition` initialisation
 * Upgrade `kemitix-parent` to 3.2.0
 * Upgrade `kemitix-checkstyle-parent` to 3.2.0
 * Upgrade `assertj` to 3.8.0

src/main/java/net/kemitix/conditional/Condition.java

@@ -21,12 +21,6 @@
 
 package net.kemitix.conditional;
 
-import java.util.AbstractMap.SimpleEntry;
-import java.util.Collections;
-import java.util.Map;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
-
 /**
  * If-then-else in a functional-style.
  *
@@ -34,14 +28,6 @@ import java.util.stream.Stream;
  */
 public interface Condition {
 
-    Condition TRUE = new TrueCondition();
-
-    Condition FALSE = new FalseCondition();
-
-    Map<Boolean, Condition> CONDITIONS = Collections.unmodifiableMap(
-            Stream.of(new SimpleEntry<>(true, TRUE), new SimpleEntry<>(false, FALSE))
-                  .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue)));
-
     /**
      * Create a new {@code Condition} for the clause.
      *
@@ -49,8 +35,9 @@ public interface Condition {
      *
      * @return the Condition
      */
+    @SuppressWarnings("avoidinlineconditionals")
     static Condition where(final boolean clause) {
-        return CONDITIONS.get(clause);
+        return clause ? TrueCondition.TRUE : FalseCondition.FALSE;
     }
 
     /**
@@ -131,59 +118,4 @@ public interface Condition {
         return where(clause);
     }
 
-    /**
-     * A {@code Condition} that has evaluated to {@code true}.
-     */
-    class TrueCondition implements Condition {
-
-        @Override
-        public Condition and(final boolean clause) {
-            return where(clause);
-        }
-
-        @Override
-        public Condition or(final boolean secondClause) {
-            return TRUE;
-        }
-
-        @Override
-        public Condition then(final Runnable response) {
-            response.run();
-            return TRUE;
-        }
-
-        @Override
-        public void otherwise(final Runnable response) {
-            // do nothing
-        }
-
-    }
-
-    /**
-     * A {@code Condition} that has evaluated to {@code false}.
-     */
-    class FalseCondition implements Condition {
-
-        @Override
-        public Condition and(final boolean clause) {
-            return FALSE;
-        }
-
-        @Override
-        public Condition or(final boolean secondClause) {
-            return where(secondClause);
-        }
-
-        @Override
-        public Condition then(final Runnable response) {
-            return FALSE;
-        }
-
-        @Override
-        public void otherwise(final Runnable response) {
-            response.run();
-        }
-
-    }
-
 }

src/main/java/net/kemitix/conditional/FalseCondition.java

@@ -0,0 +1,53 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Paul Campbell
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+ * and associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies
+ * or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
+ * AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package net.kemitix.conditional;
+
+/**
+ * A {@code Condition} that has evaluated to {@code false}.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net).
+ */
+public final class FalseCondition implements Condition {
+
+    protected static final Condition FALSE = new net.kemitix.conditional.FalseCondition();
+
+    @Override
+    public Condition and(final boolean clause) {
+        return FALSE;
+    }
+
+    @Override
+    public Condition or(final boolean secondClause) {
+        return Condition.where(secondClause);
+    }
+
+    @Override
+    public Condition then(final Runnable response) {
+        return FALSE;
+    }
+
+    @Override
+    public void otherwise(final Runnable response) {
+        response.run();
+    }
+
+}

src/main/java/net/kemitix/conditional/TrueCondition.java

@@ -0,0 +1,54 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Paul Campbell
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+ * and associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies
+ * or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
+ * AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package net.kemitix.conditional;
+
+/**
+ * A {@code Condition} that has evaluated to {@code true}.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net).
+ */
+public final class TrueCondition implements Condition {
+
+    protected static final Condition TRUE = new net.kemitix.conditional.TrueCondition();
+
+    @Override
+    public Condition and(final boolean clause) {
+        return Condition.where(clause);
+    }
+
+    @Override
+    public Condition or(final boolean secondClause) {
+        return TRUE;
+    }
+
+    @Override
+    public Condition then(final Runnable response) {
+        response.run();
+        return TRUE;
+    }
+
+    @Override
+    public void otherwise(final Runnable response) {
+        // do nothing
+    }
+
+}