added listing tags to 3.1

Author: habibasorour

source/ch3_javadatatypes.ptx

@@ -95,8 +95,8 @@
                 If this program were run on the command-line, you would enter the temperature when prompted – the Javascript pop-up for input is only an artifact of the digital textbook.
             </p>
 
-
-            <program xml:id="python-temperature-conversion" interactive="activecode" language="python">
+            <listing xml:id="python-temperature-conversion">
+            <program interactive="activecode" language="python">
                 <code>
 def main():
     fahr = int(input("Enter the temperature in F: "))
@@ -105,13 +105,15 @@ def main():
 main()
                 </code> <tests> </tests>
             </program>
+            </listing>
 
             <p>
  Next, lets look at the Java equivalent. If this program were run on the command-line, you would enter the temperature when prompted &#x2013; the &#x201C;Input for Program&#x201D; text box is only an artifact of the digital textbook. 
             </p>
 
 
-            <program xml:id="java-temperature-conversion" interactive="activecode" language="java">
+            <listing xml:id="java-temperature-conversion">
+            <program interactive="activecode" language="java">
                 <code>
 import java.util.Scanner;
 public class TempConv {
@@ -128,7 +130,8 @@ public class TempConv {
 }
                 </code> <stdin> </stdin> <tests> </tests>
             </program>
-
+            </listing>
+            
             <p>
  There are several new concepts introduced in this example. We will look at them in the following order: 
             </p>