Pulled over conventiosn

src/main/java/com/cedarsoftware/util/Convention.java

@@ -0,0 +1,69 @@
+package com.cedarsoftware.util;
+
+import java.util.Map;
+
+public class Convention {
+
+    /**
+     * statically accessed class
+     */
+    private Convention() {
+    }
+
+    /**
+     * Throws an exception if null
+     *
+     * @param value   object to check if null
+     * @param message message to use when thrown
+     * @throws IllegalArgumentException if the string passed in is null or empty
+     */
+    public static void throwIfNull(Object value, String message) {
+        if (value == null) {
+            throw new IllegalArgumentException(message);
+        }
+    }
+
+    /**
+     * Throws an exception if null or empty
+     *
+     * @param value   string to check
+     * @param message message to use when thrown
+     * @throws IllegalArgumentException if the string passed in is null or empty
+     */
+    public static void throwIfNullOrEmpty(String value, String message) {
+        if (value == null || value.isEmpty()) {
+            throw new IllegalArgumentException(message);
+        }
+    }
+
+    public static void throwIfClassNotFound(String fullyQualifiedClassName, ClassLoader loader) {
+        throwIfNullOrEmpty(fullyQualifiedClassName, "fully qualified ClassName cannot be null or empty");
+        throwIfNull(loader, "loader cannot be null");
+
+        Class<?> c = ClassUtilities.forName(fullyQualifiedClassName, loader);
+        if (c == null) {
+            throw new IllegalArgumentException("Unknown class: " + fullyQualifiedClassName + " was not found.");
+        }
+    }
+
+    public static <K, V> void throwIfKeyExists(Map<K, V> map, K key, String message) {
+        throwIfNull(map, "map cannot be null");
+        throwIfNull(key, "key cannot be null");
+
+        if (map.containsKey(key)) {
+            throw new IllegalArgumentException(message);
+        }
+    }
+
+    /**
+     * Throws an exception if the logic is false.
+     *
+     * @param logic   test to see if we need to throw the exception.
+     * @param message to include in the exception explaining why the the assertion failed
+     */
+    public static void throwIfFalse(boolean logic, String message) {
+        if (!logic) {
+            throw new IllegalArgumentException(message);
+        }
+    }
+}