1 files changed, 38 insertions, 2 deletions

diff --git a/src/main/java/org/openslx/imagemaster/util/Util.java b/src/main/java/org/openslx/imagemaster/util/Util.java
index ff0b8c1..4459a3a 100644
--- a/src/main/java/org/openslx/imagemaster/util/Util.java
+++ b/src/main/java/org/openslx/imagemaster/util/Util.java
@@ -1,16 +1,52 @@
 package org.openslx.imagemaster.util;
 
+import java.util.Random;
+
+import org.apache.log4j.Logger;
+
 public class Util
 {
+	private static Logger log = Logger.getLogger( Util.class );
 
+	/**
+	 * Check if the given object is null, abort program if true.
+	 * An optional message to be printed can be passed. A stack trace
+	 * will be printed, too. Finally the application terminates with
+	 * exit code 2.
+	 * 
+	 * This comes in handy if something must not be null, and you want
+	 * user friendsly output. A perfect example would be reading settings
+	 * from a config file. You can use this on mandatory fields.
+	 * 
+	 * @param something the object to compare to null
+	 * @param message the message to be printed if something is null
+	 */
 	public static void notNullFatal( Object something, String message )
 	{
 		if ( something == null ) {
 			if ( message != null )
-				System.out.println( "[NOTNULL] " + message );
-			System.out.println( Thread.currentThread().getStackTrace().toString() );
+				log.fatal( "[NOTNULL] " + message );
+			log.warn( Thread.currentThread().getStackTrace().toString() );
 			System.exit( 2 );
 		}
 	}
+	
+	/**
+	 * Static {@link Random} instance.
+	 */
+	private static final Random random = new Random();
+	
+	/**
+	 * Return a random integer in the range of 0 (inclusive) and
+	 * n (exclusive). Uses the internal static instance of {@link Random},
+	 * so you don't have to deal with instances everywhere.
+	 * 
+	 * @param n the upper bound (exclusive)
+	 * @return number between 0 (inclusive) and n (exclusive)
+	 */
+	public static int randomInt( int n )
+	{
+		return random.nextInt( n );
+	}
 
 }