Add comments to AbstractComponent constructors.

1 files changed, 10 insertions, 5 deletions

diff --git a/component/src/main/java/com/yahoo/component/AbstractComponent.java b/component/src/main/java/com/yahoo/component/AbstractComponent.java
index 41d4c0dc6e9..fb093c7e24c 100644
--- a/component/src/main/java/com/yahoo/component/AbstractComponent.java
+++ b/component/src/main/java/com/yahoo/component/AbstractComponent.java
@@ -24,7 +24,17 @@ public class AbstractComponent implements Component {
     protected final boolean isDeconstructable;
 
     /**
+     * Creates a new component which is invalid until {@link #initId} is called on it.
+     * The dependency injection framework (DI) will always set the id, so components to be created
+     * via DI do not have to implement other constructors, and should not set the id themselves.
+     */
+    protected AbstractComponent() {
+        isDeconstructable = setIsDeconstructable();
+    }
+
+    /**
      * Creates a new component with an id.
+     * Only for testing and components that are not created via dependency injection.
      *
      * @throws NullPointerException if the given id is null
      */
@@ -33,11 +43,6 @@ public class AbstractComponent implements Component {
         isDeconstructable = setIsDeconstructable();
     }
 
-    /** Creates a new component which is invalid until {@link #initId} is called on it. */
-    protected AbstractComponent() {
-        isDeconstructable = setIsDeconstructable();
-    }
-
     /** Initializes this. Always called from a constructor or the framework. Do not call. */
     public final void initId(ComponentId id) {
         if (this.id != null && !this.id.equals(id))