fix: demonstrate refactoring duplicate code using generics

java/src/jmri/jmrix/ecos/swing/EcosNamedPaneAction.java

@@ -1,7 +1,12 @@
 package jmri.jmrix.ecos.swing;
 
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
 import javax.swing.Icon;
+import jmri.jmrix.SystemConnectionMemo;
 import jmri.jmrix.ecos.EcosSystemConnectionMemo;
+import jmri.jmrix.swing.SystemConnectionNamedPaneAction;
 import jmri.util.swing.JmriPanel;
 import jmri.util.swing.WindowInterface;
 import org.slf4j.Logger;
@@ -12,7 +17,7 @@
  *
  * @author Bob Jacobsen Copyright (C) 2010
  */
-public class EcosNamedPaneAction extends jmri.util.swing.JmriNamedPaneAction {
+public class EcosNamedPaneAction extends SystemConnectionNamedPaneAction<EcosSystemConnectionMemo> {
 
     /**
      * Enhanced constructor for placing the pane in various GUIs.
@@ -22,17 +27,15 @@ public class EcosNamedPaneAction extends jmri.util.swing.JmriNamedPaneAction {
      * @param memo system connection.
      */
     public EcosNamedPaneAction(String s, WindowInterface wi, String paneClass, EcosSystemConnectionMemo memo) {
-        super(s, wi, paneClass);
+        super(s, wi, paneClass, memo);
         this.memo = memo;
     }
 
     public EcosNamedPaneAction(String s, Icon i, WindowInterface wi, String paneClass, EcosSystemConnectionMemo memo) {
-        super(s, i, wi, paneClass);
+        super(s, i, wi, paneClass, memo);
         this.memo = memo;
     }
 
-    EcosSystemConnectionMemo memo;
-
     @Override
     public JmriPanel makePanel() {
         JmriPanel p = super.makePanel();
@@ -52,4 +55,9 @@ public JmriPanel makePanel() {
 
     private final static Logger log = LoggerFactory.getLogger(EcosNamedPaneAction.class);
 
+    @Override
+    public Set<Class<? extends SystemConnectionMemo>> getSystemConnectionMemoClasses() {
+        return new HashSet<>(Arrays.asList(EcosSystemConnectionMemo.class));
+    }
+
 }

java/src/jmri/jmrix/nce/swing/NceNamedPaneAction.java

@@ -1,7 +1,12 @@
 package jmri.jmrix.nce.swing;
 
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
 import javax.swing.Icon;
+import jmri.jmrix.SystemConnectionMemo;
 import jmri.jmrix.nce.NceSystemConnectionMemo;
+import jmri.jmrix.swing.SystemConnectionNamedPaneAction;
 import jmri.util.swing.JmriPanel;
 import jmri.util.swing.WindowInterface;
 import org.slf4j.Logger;
@@ -13,7 +18,7 @@
  * @author Bob Jacobsen Copyright (C) 2010 Copied from LocoNet
  * @author kcameron
  */
-public class NceNamedPaneAction extends jmri.util.swing.JmriNamedPaneAction {
+public class NceNamedPaneAction extends SystemConnectionNamedPaneAction<NceSystemConnectionMemo> {
 
     /**
      * Enhanced constructor for placing the pane in various GUIs.
@@ -24,17 +29,13 @@ public class NceNamedPaneAction extends jmri.util.swing.JmriNamedPaneAction {
      * @param memo system connection memo
      */
     public NceNamedPaneAction(String s, WindowInterface wi, String paneClass, NceSystemConnectionMemo memo) {
-        super(s, wi, paneClass);
-        this.memo = memo;
+        super(s, wi, paneClass, memo);
     }
 
     public NceNamedPaneAction(String s, Icon i, WindowInterface wi, String paneClass, NceSystemConnectionMemo memo) {
-        super(s, i, wi, paneClass);
-        this.memo = memo;
+        super(s, i, wi, paneClass, memo);
     }
 
-    NceSystemConnectionMemo memo;
-
     @Override
     public JmriPanel makePanel() {
         JmriPanel p = super.makePanel();
@@ -52,6 +53,10 @@ public JmriPanel makePanel() {
         return p;
     }
 
-    private final static Logger log = LoggerFactory.getLogger(NceNamedPaneAction.class);
+    @Override
+    public Set<Class<? extends SystemConnectionMemo>> getSystemConnectionMemoClasses() {
+        return new HashSet<>(Arrays.asList(NceSystemConnectionMemo.class));
+    }
 
+    private final static Logger log = LoggerFactory.getLogger(NceNamedPaneAction.class);
 }

java/src/jmri/jmrix/swing/AbstractSystemConnectionAction.java

@@ -32,9 +32,6 @@ public M getSystemConnectionMemo() {
 
     /**
      * {@inheritDoc}
-     * <p>
-     * Note that this accepts any subclass of SystemConnectionMemo, not just
-     * subclasses of M, to avoid compilation problems elsewhere.
      * 
      * @throws IllegalArgumentException if the memo is not assignable from any
      *                                  class listed in

java/src/jmri/jmrix/swing/SystemConnectionNamedPaneAction.java

@@ -0,0 +1,52 @@
+package jmri.jmrix.swing;
+
+import javax.swing.Icon;
+import jmri.jmrix.SystemConnectionMemo;
+import jmri.util.swing.JmriNamedPaneAction;
+import jmri.util.swing.WindowInterface;
+
+/**
+ * {@link JmriNamedPaneAction} that implements {@link SystemConnectionAction}.
+ * 
+ * @author Randall Wood Copyright 2020
+ * @param <M> the supported subclass of {@link SystemConnectionMemo}
+ */
+public abstract class SystemConnectionNamedPaneAction<M extends SystemConnectionMemo> extends JmriNamedPaneAction implements SystemConnectionAction<M> {
+
+    protected M memo;
+
+    public SystemConnectionNamedPaneAction(String s, String paneClass, M memo) {
+        super(s, paneClass);
+        this.memo = memo;
+    }
+
+    public SystemConnectionNamedPaneAction(String s, Icon i, WindowInterface wi, String paneClass, M memo) {
+        super(s, i, wi, paneClass);
+        this.memo = memo;
+    }
+
+    public SystemConnectionNamedPaneAction(String s, WindowInterface wi, String paneClass, M memo) {
+        super(s, wi, paneClass);
+        this.memo = memo;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public M getSystemConnectionMemo() {
+        return memo;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void setSystemConnectionMemo(M memo) {
+        if (getSystemConnectionMemoClasses().stream().anyMatch(memo.getClass()::isAssignableFrom)) {
+            this.memo = memo;
+        } else {
+            throw new IllegalArgumentException(memo.getClass() + " is not valid for " + this.getClass());
+        }
+    }
+}