Fix warnings: don't use '_' as variable name.

Author: dhendriks

src/main/java/com/github/javabdd/BDDFactory.java

@@ -35,7 +35,7 @@ public abstract class BDDFactory {
     public static final String getProperty(String key, String def) {
         try {
             return System.getProperty(key, def);
-        } catch (AccessControlException _) {
+        } catch (AccessControlException e) {
             return def;
         }
     }
@@ -95,10 +95,10 @@ public static BDDFactory init(String bddpackage, int nodenum, int cachesize)
       return (BDDFactory) m.invoke(null, new Object[]
 	{ new Integer(nodenum), new Integer(cachesize) });
     }
-    catch (ClassNotFoundException _) {}
-    catch (NoSuchMethodException _) {}
-    catch (IllegalAccessException _) {}
-    catch (InvocationTargetException _) {}
+    catch (ClassNotFoundException e) {}
+    catch (NoSuchMethodException e) {}
+    catch (IllegalAccessException e) {}
+    catch (InvocationTargetException e) {}
     // falling back to default java implementation.
     return JFactory.init(nodenum, cachesize);
   }
@@ -495,7 +495,7 @@ public BDD load(String filename) throws IOException {
             BDD result = load(r);
             return result;
         } finally {
-            if (r != null) try { r.close(); } catch (IOException _) { }
+            if (r != null) try { r.close(); } catch (IOException e) { }
         }
     }
     // TODO: error code from bdd_load (?)
@@ -657,7 +657,7 @@ public void save(String filename, BDD var) throws IOException {
             is = new BufferedWriter(new FileWriter(filename));
             save(is, var);
         } finally {
-            if (is != null) try { is.close(); } catch (IOException _) { }
+            if (is != null) try { is.close(); } catch (IOException e) { }
         }
     }
     // TODO: error code from bdd_save (?)

src/main/java/com/github/javabdd/FindBestOrder.java

@@ -196,7 +196,7 @@ public void readBDDConfig(BDDFactory bdd) {
                 }
             } catch (IOException x) {
             } finally {
-                if (in != null) try { in.close(); } catch (IOException _) { }
+                if (in != null) try { in.close(); } catch (IOException e) { }
             }
         }
 

src/main/java/com/github/javabdd/TryVarOrder.java

@@ -59,7 +59,7 @@ void initBDDFactory(String s) {
                 }
             } catch (IOException x) {
             } finally {
-                if (in != null) try { in.close(); } catch (IOException _) { }
+                if (in != null) try { in.close(); } catch (IOException e) { }
             }
         } catch (Exception x) {
             System.err.println("Exception occurred while initializing BDD factory: "+x.getLocalizedMessage());