add switch default

Author: BamaCharanChhandogi

src/main/java/com/thealgorithms/datastructures/hashmap/hashing/Main.java

@@ -44,6 +44,9 @@ public static void main(String[] args) {
                 In.close();
                 return;
             }
+            default: {
+                throw new IllegalArgumentException("Unexpected value: " + choice);
+            }
             }
         }
     }

src/main/java/com/thealgorithms/datastructures/hashmap/hashing/MainCuckooHashing.java

@@ -62,6 +62,9 @@ public static void main(String[] args) {
                 h.reHashTableIncreasesTableSize();
                 break;
             }
+            default: {
+                throw new IllegalArgumentException("Unexpected value: " + choice);
+            }
             }
         }
     }

src/main/java/com/thealgorithms/misc/Sort012D.java

@@ -51,6 +51,9 @@ public static void sort012(int[] a) {
                 h--;
                 break;
             }
+            default: {
+                throw new IllegalArgumentException("Unexpected value: " + a[mid]);
+            }
             }
         }
         System.out.println("the Sorted array is ");

src/main/java/com/thealgorithms/sorts/DNFSort.java

@@ -31,6 +31,8 @@ static void sort012(int[] a, int arr_size) {
                 high--;
                 break;
             }
+            default:
+                throw new IllegalArgumentException("Unexpected value: " + a[mid]);
             }
         }
     }

src/main/java/com/thealgorithms/stacks/PostfixToInfix.java

@@ -28,9 +28,9 @@ public static boolean isOperator(char token) {
         case '*':
         case '^':
             return true;
+        default:
+            return false;
         }
-
-        return false;
     }
 
     public static boolean isValidPostfixExpression(String postfix) {

src/main/java/com/thealgorithms/strings/ValidParentheses.java

@@ -26,6 +26,8 @@ public static boolean isValid(String s) {
             case ']':
                 if (head == 0 || stack[--head] != '[') return false;
                 break;
+            default:
+                throw new IllegalArgumentException("Unexpected character: " + c);
             }
         }
         return head == 0;