add listing tags

Author: habibasorour

source/ch8_filehandling.ptx

@@ -75,8 +75,8 @@
         <p>
             We will now create a <c>File</c> object. It is important to create a meaningful name for the <c>File</c> object. We will call ours <c>myFile</c>, and we will call our class <c>CreateFileObject</c>.
         </p>
-        
-        <program xml:id="create-file-object-java" interactive="activecode" language="java" add-files="myfile-created">
+        <listing xml:id="create-file-object-java">
+        <program interactive="activecode" language="java" add-files="myfile-created">
             <code>
 import java.io.File;
 
@@ -90,6 +90,7 @@ public class CreateFile {
 }
             </code> 
         </program>
+        </listing>
 
         <note>
             <p>
@@ -105,8 +106,8 @@ public class CreateFile {
         <p>
             First, lets look at the equivalent Python code:
         </p>
-        
-        <program xml:id="create-file-python" interactive="activecode" language="python">
+        <listing xml:id="create-file-python">
+        <program interactive="activecode" language="python">
             <code>
             filename = "newfile.txt"
             print("Attempting to write to '" + filename + "' using 'w' mode...")
@@ -120,12 +121,13 @@ public class CreateFile {
 
             </code> 
         </program>
+        </listing>
 
         <p>
             Now, let's look at Java code that accomplishes the same task:
         </p>
-        
-        <program xml:id="create-file-java" interactive="activecode" language="java">
+        <listing xml:id="create-file-java">
+        <program interactive="activecode" language="java">
             <code>
             import java.io.File;
             import java.io.IOException;
@@ -148,6 +150,7 @@ public class CreateFile {
             }
             </code> 
         </program>
+        </listing>
 
         <note>
             <p>