Lab 6 demo

app/src/main/java/com/example/simpleparadox/listycity/CityList.java

@@ -22,6 +22,22 @@ public void add(City city) {
         cities.add(city);
     }
 
+     /**
+     * This delete a city to the list if the city exists
+     * @param city
+     *      This is a candidate city to delete
+     */
+    public void delete(City city) {
+        if (cities.contains(city)) {
+            cities.remove(city);
+
+        }
+        else{
+            throw new IllegalArgumentException();
+        }
+
+    }
+
     /**
      * This returns a sorted list of cities
      * @return
@@ -32,5 +48,14 @@ public List<City> getCities() {
         Collections.sort(list);
         return list;
     }
+
+    /**
+     * This returns a number of cities
+     * @return
+     *      Return the total sum of city number
+     */
+    public int getCount() {
+        return cities.size();
+    }
 
 }

app/src/test/java/com/example/simpleparadox/listycity/CityListTest.java

@@ -54,5 +54,45 @@ void testGetCities() {
         assertEquals(0, city.compareTo(cityList.getCities().get(0)));
         assertEquals(0, mockCity().compareTo(cityList.getCities().get(1)));
     }
+
+     @Test
+    void testDelete() {
+        CityList cityList = mockCityList();
+
+        assertEquals(1, cityList.getCities().size());
+
+        City city = new City("Edmonton", "Alberta");
+        cityList.delete(city);
+
+        assertEquals(0, cityList.getCities().size());
+        assertFalse(cityList.getCities().contains(city));
+    }
+
+    @Test
+    void testDeleteException() {
+        CityList cityList = mockCityList();
+
+        City city = new City("Yellowknife", "Northwest Territories");
+        cityList.delete(city);
+
+        assertThrows(IllegalArgumentException.class, () -> {
+            cityList.delete(city);
+        });
+    }
+     @Test
+    void testGetCount()
+    {
+        CityList cityList = mockCityList();
+
+        assertEquals(0, cityList.getCount());
+
+        City city = new City("Charlottetown", "Prince Edward Island");
+        cityList.add(city);
+        assertEquals(1, cityList.getCount());
+
+        City city2 = new City("Yellowknife", "Northwest Territories");
+        cityList.add(city2);
+        assertEquals(2, cityList.getCount());
+    }
 
-}
+}