Update demo

demo/src/main/java/jackfruit/demo/JackfruitDemo.java

@@ -9,9 +9,9 @@ package jackfruit.demo;
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -23,6 +23,7 @@ package jackfruit.demo;
 import java.io.File;
 import java.io.IOException;
 import java.io.PrintWriter;
+import java.util.ArrayList;
 import java.util.List;
 import org.apache.commons.configuration2.PropertiesConfiguration;
 import org.apache.commons.configuration2.PropertiesConfigurationLayout;
@@ -89,14 +90,21 @@ public class JackfruitDemo {
       System.out.println("random.toUpperCase() = " + random.toUpperCase());
 
     // create a new factory with a different prefix, but same parameters
+    System.out.println();
+    System.out.println(
+        "Create a config with anotherPrefix and retrieve randoms.  This will throw an exception.");
     factory = new DemoClassFactory("anotherPrefix");
     template = factory.fromConfig(config);
 
-    // this will not find anything, since template was created from the original config, which
-    // uses the original prefix.
-    randoms = template.randoms();
+    // this will throw an exception since anotherPrefix.randoms is not one of the keys in the
+    // configuration.
+    try {
+      randoms = template.randoms();
+    } catch (Exception e) {
+      System.out.println("Caught expected RuntimeException:\n" + e.getLocalizedMessage());
+      randoms = new ArrayList<>();
+    }
     for (SomeRandomClass random : randoms)
       System.out.println("random.toUpperCase() = " + random.toUpperCase());
   }
-
 }

jackfruit/src/main/java/jackfruit/processor/ConfigProcessor.java

@@ -123,7 +123,7 @@ public class ConfigProcessor extends AbstractProcessor {
 
           Jackfruit configParams = annotatedType.getAnnotation(Jackfruit.class);
           String prefix = configParams.prefix().strip();
-          if (prefix.length() > 0 && !prefix.endsWith(".")) prefix += ".";
+          if (!prefix.isEmpty() && !prefix.endsWith(".")) prefix += ".";
 
           // This is the templatized class with annotations to be processed (e.g.
           // ConfigTemplate)
@@ -317,7 +317,7 @@ public class ConfigProcessor extends AbstractProcessor {
               Diagnostic.Kind.ERROR,
               String.format(
                   "Unsupported kind %s for type %s!",
-                  erasure.getKind().toString(), erasure.toString()));
+                  erasure.getKind().toString(), erasure));
     }
 
     builder.addAllTypeArgs(typeArgs);
@@ -354,7 +354,7 @@ public class ConfigProcessor extends AbstractProcessor {
 
     AnnotationBundle bundle = builder.build();
     if (ConfigProcessorUtils.isList(bundle.erasure(), processingEnv)
-        && bundle.typeArgs().size() == 0)
+        && bundle.typeArgs().isEmpty())
       messager.printMessage(
           Diagnostic.Kind.ERROR,
           String.format("No parameter type for List on method %s!", e.getSimpleName()));
@@ -473,7 +473,7 @@ public class ConfigProcessor extends AbstractProcessor {
       }
 
       // add the comment
-      if (ab.comment().length() > 0) {
+      if (!ab.comment().isEmpty()) {
         String commentName = String.format("%sComment", method.getSimpleName());
         methodBuilder.addStatement("$T $L = $S", String.class, commentName, ab.comment());
         methodBuilder.addStatement(
@@ -570,7 +570,7 @@ public class ConfigProcessor extends AbstractProcessor {
           if (ConfigProcessorUtils.isString(bundle.erasure(), processingEnv)) {
             builder.addStatement("return $S", bundle.defaultValue());
           } else {
-            if (bundle.defaultValue().trim().length() == 0) {
+            if (bundle.defaultValue().trim().isEmpty()) {
               processingEnv
                   .getMessager()
                   .printMessage(
@@ -624,7 +624,7 @@ public class ConfigProcessor extends AbstractProcessor {
       builder.addStatement("String key = $N + $S", prefix, bundle.key());
       builder
           .beginControlFlow("if (!config.containsKey(key))")
-          .addStatement("throw new $T($S + key)", RuntimeException.class, "No such key")
+          .addStatement("throw new $T($S + key)", RuntimeException.class, "No such key ")
           .endControlFlow();
 
       TypeMirror parser = null;