refactor

school/ManagementSys.java

@@ -0,0 +1,40 @@
+package school;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class ManagementSys {
+    private static ManagementSys instance = null;
+    private List<Person> persons;
+
+    private ManagementSys() {
+        persons = new ArrayList<Person>();
+    }
+
+    public static ManagementSys getInstance() {
+        if (instance == null) {
+            instance = new ManagementSys();
+        }
+        return instance;
+    }
+
+    public void addPerson(Person person) {
+        persons.add(person);
+    }
+
+    public void removePerson(Person person) {
+        persons.remove(person);
+    }
+
+    public void updatePerson(int index, Person person) {
+        persons.set(index, person);
+    }
+
+    public List<Person> getPersons() {
+        return persons;
+    }
+
+    public void setPersons(List<Person> persons) {
+        this.persons = persons;
+    }
+}