Merge pull request iluwatar#794 from iluwatar/Issue781

iluwatar · web-flow · commit b079aec1fdf6 · 2018-09-25T22:45:25.000+03:00
iluwatar#781 Resolved ClasscastException from Acyclic Visitor
diff --git a/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/AllModemVisitor.java b/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/AllModemVisitor.java
@@ -23,8 +23,9 @@
 package com.iluwatar.acyclicvisitor;
 
 /**
- * All ModemVisitor interface extends all visitor interfaces
+ * All ModemVisitor interface extends all visitor interfaces. This interface
+ * provides ease of use when a visitor needs to visit all modem types.
  */
-public interface AllModemVisitor extends ModemVisitor, ZoomVisitor, HayesVisitor{
+public interface AllModemVisitor extends ZoomVisitor, HayesVisitor{
 
 }
diff --git a/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/ConfigureForUnixVisitor.java b/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/ConfigureForUnixVisitor.java
@@ -27,9 +27,10 @@
 
 /**
  * ConfigureForUnixVisitor class implements zoom's visit method for Unix 
- * manufacturer
+ * manufacturer, unlike traditional visitor pattern, this class may selectively implement
+ * visit for other modems.
  */
-public class ConfigureForUnixVisitor implements ModemVisitor, ZoomVisitor {
+public class ConfigureForUnixVisitor implements ZoomVisitor {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(ConfigureForUnixVisitor.class);
 
diff --git a/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/Hayes.java b/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/Hayes.java
@@ -37,10 +37,10 @@ public class Hayes extends Modem {
    */
   @Override
   public void accept(ModemVisitor modemVisitor) {
-    try {
+    if (modemVisitor instanceof HayesVisitor) {
       ((HayesVisitor) modemVisitor).visit(this);
-    } catch (ClassCastException e) {
-      LOGGER.error("Unable to cast to HayesVisitor");
+    } else {
+      LOGGER.info("Only HayesVisitor is allowed to visit Hayes modem");
     }
 
   }
diff --git a/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/Zoom.java b/acyclic-visitor/src/main/java/com/iluwatar/acyclicvisitor/Zoom.java
@@ -37,10 +37,10 @@ public class Zoom extends Modem {
    */
   @Override
   public void accept(ModemVisitor modemVisitor) {
-    try {
+    if (modemVisitor instanceof  ZoomVisitor) {
       ((ZoomVisitor) modemVisitor).visit(this);
-    } catch (ClassCastException e) {
-      LOGGER.error("Unable to cast to ZoomVisitor");
+    } else {
+      LOGGER.info("Only ZoomVisitor is allowed to visit Zoom modem");
     }
   }
   

Original file line number	Diff line number	Diff line change
`@@ -37,10 +37,10 @@ public class Hayes extends Modem {`
`37`	`37`	`*/`
`38`	`38`	`@Override`
`39`	`39`	`public void accept(ModemVisitor modemVisitor) {`
`40`		`- try {`
	`40`	`+ if (modemVisitor instanceof HayesVisitor) {`
`41`	`41`	`((HayesVisitor) modemVisitor).visit(this);`
`42`		`- } catch (ClassCastException e) {`
`43`		`- LOGGER.error("Unable to cast to HayesVisitor");`
	`42`	`+ } else {`
	`43`	`+ LOGGER.info("Only HayesVisitor is allowed to visit Hayes modem");`
`44`	`44`	`}`
`45`	`45`
`46`	`46`	`}`
Original file line number	Diff line number	Diff line change
`@@ -37,10 +37,10 @@ public class Zoom extends Modem {`
`37`	`37`	`*/`
`38`	`38`	`@Override`
`39`	`39`	`public void accept(ModemVisitor modemVisitor) {`
`40`		`- try {`
	`40`	`+ if (modemVisitor instanceof ZoomVisitor) {`
`41`	`41`	`((ZoomVisitor) modemVisitor).visit(this);`
`42`		`- } catch (ClassCastException e) {`
`43`		`- LOGGER.error("Unable to cast to ZoomVisitor");`
	`42`	`+ } else {`
	`43`	`+ LOGGER.info("Only ZoomVisitor is allowed to visit Zoom modem");`
`44`	`44`	`}`
`45`	`45`	`}`
`46`	`46`