Refactored all solutions

Java/Object Oriented Programming/Calculating Volume/Solution.java

@@ -16,10 +16,10 @@ import java.security.Permission;
 
 class Calculate {
     static Scanner scan = new Scanner(System.in);
-    static Output output = new Output();
+    static Calculate output = new Calculate();
 
     public static Calculate do_calc() {
-        return new Calculate();
+        return output;
     }
     
     public int get_int_val() throws IOException, NumberFormatException {
@@ -54,13 +54,64 @@ class Calculate {
         return  Math.PI * (r * r) * h;
     }
     
-    static void display (double value) {
-        System.out.println(value);
-    }
-}
-
-class Output {
     void display(double value) {
         System.out.format("%.3f%n", value);
     }
 }
+
+public class Solution {
+    public static void main(String[] args) {
+        DoNotTerminate.forbidExit();
+        try {
+            Calculate cal = new Calculate();
+            int T = cal.get_int_val();
+            while (T--> 0) {
+                double volume = 0.0;
+                int ch = cal.get_int_val();
+                if (ch == 1) {
+                    int a = cal.get_int_val();
+                    volume = Calculate.do_calc().get_volume(a);
+                } else if (ch == 2) {
+                    int l = cal.get_int_val();
+                    int b = cal.get_int_val();
+                    int h = cal.get_int_val();
+                    volume = Calculate.do_calc().get_volume(l, b, h);
+                } else if (ch == 3) {
+                    double r = cal.get_double_val();
+                    volume = Calculate.do_calc().get_volume(r);
+                } else if (ch == 4) {
+                    double r = cal.get_double_val();
+                    double h = cal.get_double_val();
+                    volume = Calculate.do_calc().get_volume(r, h);
+                }
+                cal.output.display(volume);
+            }
+        } catch (NumberFormatException e) {
+            System.out.print(e);
+        } catch (IOException e) {
+            e.printStackTrace();
+        } catch (DoNotTerminate.ExitTrappedException e) {
+            System.out.println("Unsuccessful Termination!!");
+        }
+    } // end of main
+} //end of Solution
+
+/**
+*This class prevents the user form using System.exit(0)
+* from terminating the program abnormally.
+*
+*/
+class DoNotTerminate {
+    public static class ExitTrappedException extends SecurityException {}
+    public static void forbidExit() {
+        final SecurityManager securityManager = new SecurityManager() {
+            @Override
+            public void checkPermission(Permission permission) {
+                if (permission.getName().contains("exitVM")) {
+                 throw new ExitTrappedException();
+                }
+            }
+        };
+        System.setSecurityManager(securityManager);
+    }
+} //end of Do_Not_Terminate