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Pattern Prototype
Prototype pattern is one of the Creational Design pattern, so it provides a mechanism of object creation. Prototype pattern is used when the Object creation is a costly affair and requires a lot of time and resources and you have a similar object already existing. So this pattern provides a mechanism to copy the original object to a new object and then modify it according to our needs. This pattern uses Java cloning to copy the object.
Screenshot of the Full code
import java.util.ArrayList;
import java.util.List;
public class Users implements Cloneable{
private List<String> empList;
public Users(){
empList = new ArrayList<>();
}
public Users(List<String> list){
this.empList=list;
}
//read some data from the database.
public void loadData(){
empList.add("japak");
empList.add("King");
empList.add("David");
empList.add("Romeo");
}
public List<String> getEmpList() {
return empList;
}
@Override
public Object clone() throws CloneNotSupportedException{
List<String> temp = new ArrayList<String>();
for(String s : this.getEmpList()){
temp.add(s);
}
return new Users(temp);
}
}
//Notice that the clone method is overridden to provide a deep copy of the users list.Here's the program that will show the benefit of the Prototype pattern usage.
public class PrototypePatternTest {
public static void main(String[] args) throws CloneNotSupportedException {
Users usr = new Users();
user.loadData();
//Use the clone method to get the User object
Users useNew = (Users) user.clone();
Users useNew1 = (Users) user.clone();
List<String> list = useNew.getEmpList();
list.add("John");
List<String> list1 = usersNew1.getEmpList();
list1.remove("Pankaj");
System.out.println("users List: "+ users.getEmpList());
System.out.println("users New List: "+list);
System.out.println("users New1 List: "+list1);
}
}