--- a/src/goodjava/logging/LoggerFactory.java	Tue Feb 18 14:54:35 2020 -0700
+++ b/src/goodjava/logging/LoggerFactory.java	Sun Feb 23 18:14:32 2020 -0700
@@ -1,17 +1,26 @@
 package goodjava.logging;
 
 
-public abstract class LoggerFactory {
-	public static LoggerFactory implementation = new Log4jFactory();
-
-	protected abstract Logger getLoggerImpl(Class cls);
-	protected abstract Logger getLoggerImpl(String name);
-
-	public static Logger getLogger(Class cls) {
-		return implementation.getLoggerImpl(cls);
+public final class LoggerFactory {
+	public static final ILoggerFactory implementation;
+	static {
+		String s = System.getProperty("goodjava.logger","goodjava.logging.Log4jFactory");
+		try {
+			implementation = (ILoggerFactory)Class.forName(s).newInstance();
+		} catch(ClassNotFoundException e) {
+			throw new RuntimeException(e);
+		} catch(InstantiationException e) {
+			throw new RuntimeException(e);
+		} catch(IllegalAccessException e) {
+			throw new RuntimeException(e);
+		}
 	}
 
 	public static Logger getLogger(String name) {
-		return implementation.getLoggerImpl(name);
+		return implementation.getLogger(name);
+	}
+
+	public static Logger getLogger(Class cls) {
+		return getLogger(cls.getName());
 	}
 }