build: fix checktyle erros + simplify Java version detection

Author: jknack

handlebars/src/main/java/com/github/jknack/handlebars/Handlebars.java

@@ -17,9 +17,6 @@
  */
 package com.github.jknack.handlebars;
 
-import com.github.jknack.handlebars.helper.I18nHelper;
-import com.github.jknack.handlebars.internal.Files;
-import com.github.jknack.handlebars.internal.Throwing;
 import static org.apache.commons.lang3.Validate.isTrue;
 import static org.apache.commons.lang3.Validate.notEmpty;
 import static org.apache.commons.lang3.Validate.notNull;
@@ -39,25 +36,27 @@
 import java.util.List;
 import java.util.Map.Entry;
 import java.util.Set;
-import java.util.concurrent.atomic.AtomicInteger;
+
+import javax.script.Bindings;
+import javax.script.ScriptEngine;
+import javax.script.ScriptEngineManager;
 
 import org.slf4j.Logger;
 
 import com.github.jknack.handlebars.cache.NullTemplateCache;
 import com.github.jknack.handlebars.cache.TemplateCache;
 import com.github.jknack.handlebars.helper.DefaultHelperRegistry;
+import com.github.jknack.handlebars.helper.I18nHelper;
+import com.github.jknack.handlebars.internal.Files;
 import com.github.jknack.handlebars.internal.FormatterChain;
 import com.github.jknack.handlebars.internal.HbsParserFactory;
+import com.github.jknack.handlebars.internal.Throwing;
 import com.github.jknack.handlebars.io.ClassPathTemplateLoader;
 import com.github.jknack.handlebars.io.CompositeTemplateLoader;
 import com.github.jknack.handlebars.io.StringTemplateSource;
 import com.github.jknack.handlebars.io.TemplateLoader;
 import com.github.jknack.handlebars.io.TemplateSource;
 
-import javax.script.Bindings;
-import javax.script.ScriptEngine;
-import javax.script.ScriptEngineManager;
-
 /**
  * <p>
  * Handlebars provides the power necessary to let you build semantic templates effectively with no
@@ -177,8 +176,12 @@ public boolean equals(final Object obj) {
    */
   public static class Utils {
 
+    /** Current Java version: 8, 11, 15, etc. */
     public static final int javaVersion = javaVersion();
 
+    /** Prefix for Java version: 1.8 (mostly). */
+    private static final String VERSION_PREFIX = "1.";
+
     /**
      * Evaluate the given object and return true is the object is considered
      * empty. Nulls, empty list or array and false values are considered empty.
@@ -237,21 +240,9 @@ public static CharSequence escapeExpression(final CharSequence input) {
       return EscapingStrategy.DEF.escape(input);
     }
 
-    private static int javaVersion() {
-      String version = System.getProperty("java.version");
-      if (version.startsWith("1.")) {
-        version = version.substring(2, 3);
-      } else {
-        int dot = version.indexOf(".");
-        if (dot != -1) {
-          version = version.substring(0, dot);
-        }
-      }
-      try {
-        return Integer.parseInt(version);
-      } catch (NumberFormatException e) {
-        return 8;
-      }
+    static int javaVersion() {
+      String version = System.getProperty("java.specification.version").trim();
+      return Integer.parseInt(version.replace(VERSION_PREFIX, ""));
     }
   }
 

handlebars/src/main/java/com/github/jknack/handlebars/internal/BaseTemplate.java

@@ -57,6 +57,9 @@
  */
 abstract class BaseTemplate implements Template {
 
+  /** Java 15. */
+  private static final int JAVA_15 = 15;
+
   /**
    * The handlebars object. Required.
    */
@@ -265,18 +268,18 @@ private boolean isDefault(final Method method) {
 
           private Object invokeDefaultMethod(final Method method, final Class<?> lookupClass,
               final Object proxy, final Object... args) throws Throwable {
-            if (Handlebars.Utils.javaVersion >= 15) {
+            if (Handlebars.Utils.javaVersion >= JAVA_15) {
               MethodType methodType = MethodType.methodType(method.getReturnType(),
                   method.getParameterTypes());
               return MethodHandles.lookup()
                   .findSpecial(lookupClass, method.getName(), methodType, lookupClass)
                   .bindTo(proxy)
                   .invokeWithArguments(args);
             } else {
-              // Jumping through these hoops is needed because calling unreflectSpecial requires that
-              // the lookup instance have private access to the special caller. None of the static
-              // factory methods for Lookup will give us an instance with the access modes we need,
-              // so we work around it by calling the private constructor via reflection.
+              // Jumping through these hoops is needed because calling unreflectSpecial requires
+              // that the lookup instance have private access to the special caller. None of the
+              // static factory methods for Lookup will give us an instance with the access modes
+              // we need, so we work around it by calling the private constructor via reflection.
               Constructor<MethodHandles.Lookup> constructor = MethodHandles.Lookup.class
                   .getDeclaredConstructor(Class.class, int.class);
               constructor.setAccessible(true);

handlebars/src/test/java/com/github/jknack/handlebars/JavaVersionTest.java

@@ -0,0 +1,69 @@
+package com.github.jknack.handlebars;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assume.assumeTrue;
+
+import org.junit.Test;
+
+public class JavaVersionTest {
+
+  @Test
+  public void shouldCheckVersion8() {
+    assumeTrue(Handlebars.Utils.javaVersion() == 8);
+    assertEquals(8, Handlebars.Utils.javaVersion());
+  }
+
+  @Test
+  public void shouldCheckVersion9() {
+    assumeTrue(Handlebars.Utils.javaVersion() == 9);
+    assertEquals(9, Handlebars.Utils.javaVersion());
+  }
+
+  @Test
+  public void shouldCheckVersion10() {
+    assumeTrue(Handlebars.Utils.javaVersion() == 10);
+    assertEquals(10, Handlebars.Utils.javaVersion());
+  }
+
+  @Test
+  public void shouldCheckVersion11() {
+    assumeTrue(Handlebars.Utils.javaVersion() == 11);
+    assertEquals(11, Handlebars.Utils.javaVersion());
+  }
+
+  @Test
+  public void shouldCheckVersion12() {
+    assumeTrue(Handlebars.Utils.javaVersion() == 12);
+    assertEquals(12, Handlebars.Utils.javaVersion());
+  }
+
+  @Test
+  public void shouldCheckVersion13() {
+    assumeTrue(Handlebars.Utils.javaVersion() == 13);
+    assertEquals(13, Handlebars.Utils.javaVersion());
+  }
+
+  @Test
+  public void shouldCheckVersion14() {
+    assumeTrue(Handlebars.Utils.javaVersion() == 14);
+    assertEquals(14, Handlebars.Utils.javaVersion());
+  }
+
+  @Test
+  public void shouldCheckVersion15() {
+    assumeTrue(Handlebars.Utils.javaVersion() == 15);
+    assertEquals(15, Handlebars.Utils.javaVersion());
+  }
+
+  @Test
+  public void shouldCheckVersion16() {
+    assumeTrue(Handlebars.Utils.javaVersion() == 16);
+    assertEquals(16, Handlebars.Utils.javaVersion());
+  }
+
+  @Test
+  public void shouldCheckVersion17() {
+    assumeTrue(Handlebars.Utils.javaVersion() == 17);
+    assertEquals(17, Handlebars.Utils.javaVersion());
+  }
+}