diff --git a/代码/workspace_robo4/robocode.api/src/main/java/net/sf/robocode/core/ContainerBase.java b/代码/workspace_robo4/robocode.api/src/main/java/net/sf/robocode/core/ContainerBase.java
index 341c6a8..f7a6d40 100644
--- a/代码/workspace_robo4/robocode.api/src/main/java/net/sf/robocode/core/ContainerBase.java
+++ b/代码/workspace_robo4/robocode.api/src/main/java/net/sf/robocode/core/ContainerBase.java
@@ -12,7 +12,7 @@ package net.sf.robocode.core;
  * @author Pavel Savara (original)
  */
 public abstract class ContainerBase {
-	public static ContainerBase instance;
+	public static final ContainerBase instance;
 
 	protected abstract <T> T getBaseComponent(java.lang.Class<T> tClass);
 
diff --git a/代码/workspace_robo4/robocode.api/src/main/java/net/sf/robocode/io/FileUtil.java b/代码/workspace_robo4/robocode.api/src/main/java/net/sf/robocode/io/FileUtil.java
index c9994b3..5de6431 100644
--- a/代码/workspace_robo4/robocode.api/src/main/java/net/sf/robocode/io/FileUtil.java
+++ b/代码/workspace_robo4/robocode.api/src/main/java/net/sf/robocode/io/FileUtil.java
@@ -31,7 +31,7 @@ public class FileUtil {
 
 			FileUtil.setCwd(new File(wd));
 		} catch (IOException e) {
-			e.printStackTrace();
+			LOGGER.log("context", e);
 		}
 	}