JNI loading errors are now all logged so they are also visible when

using the high level API and so ALL four error messages are displayed
and not just the last one.

src/main/java/de/ailis/usb4java/jni/USB.java

@@ -5,8 +5,13 @@
 
 package de.ailis.usb4java.jni;
 
+import java.io.PrintWriter;
+import java.io.StringWriter;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.logging.Logger;
 
 
 /**
@@ -19,6 +24,9 @@ import java.nio.ByteOrder;
 
 public final class USB
 {
+    /** The logger. */
+    private static final Logger LOG = Logger.getLogger("USB");
+
     /** The maximum size of a descriptor. */
     private static final int MAX_DESCRIPTOR_SIZE = 256;
 
@@ -218,24 +226,31 @@ public final class USB
 
     static
     {
-        Throwable lastException = null;
+        final List<Throwable> errors = new ArrayList<Throwable>();
         for (final String libName : libNames)
         {
             try
             {
                 System.loadLibrary(libName);
-                lastException = null;
+                errors.clear();
                 break;
             }
             catch (final Throwable e)
             {
-                lastException = e;
+                errors.add(e);
             }
         }
-        if (lastException != null)
+        if (!errors.isEmpty())
+        {
+            final StringWriter out = new StringWriter();
+            for (final Throwable error: errors)
+            {
+                error.printStackTrace(new PrintWriter(out));
+            }
+            LOG.severe(out.toString());
             throw new RuntimeException(
-                "Unable to load JNI library of usb4java: "
-                    + lastException, lastException);
+                "Unable to load JNI library of usb4java");
+        }
     }