CODEWITHSUNDEEP
java
Josip Maričević
Josip Maričević

Reputation: 417

How to create class object depending on one statement

I have trouble with creating class objects. I have two classes, Employee and Article. Both of them have same methods(edit(), remove(), save(), list()). Now I want to create object "obj" from the specific class, depending on the string "item", so I can use him later like showed bellow.

My method

    private void subMenu(String item) {

        switch(item) {
            case "employee":
                Employee obj = new Employee();
                break;
            case "article":
                Article obj = new Article();
                break;
        }
        obj.edit();
        obj.remove();
        ...
    }

I tried something like this but it just throws Exception: 

 Duplicate local variable obj

Class Article

public class Article() {

    public void edit() {

    }

    public void remove() {

    }

    public void save() {

    }

    public void list() {

    }
}

Class Employee

public class Employee() {

    public void edit() {

    }

    public void remove() {

    }

    public void save() {

    }

    public void list() {

    }
}

Upvotes: 0

Views: 941

Answers (2)

Dorian Gray
Dorian Gray

Reputation: 2981

1) Create an interface with all common methods (give it a better name than Item):

public interface Item {

    void edit();

    void remove();

    void save();

    void list();
}

2) Make both classes implement that interface:

public class Article implements Item {

    public void edit() {

    }

    public void remove() {

    }

    public void save() {

    }

    public void list() {

    }
}

3) Replace local variables with Item:

private void subMenu(String item) {
    Item obj;
    switch(item) {
        case "employee":
            obj = new Employee();
            break;
        case "article":
            obj = new Article();
            break;
       default:
            return; //FIXME Can it happen?
    }
    obj.edit();
    obj.remove();
    ...
}

Upvotes: 5

Lungu Daniel
Lungu Daniel

Reputation: 844

You could create an interface with that methods:

public interface InterfaceName {
    void edit();
    void remove();
    void save();
    void list();
}

and implement it to Article and Employee classes

public class Employee implements InterfaceName {
  ....
}

public class Article implements InterfaceName {
  ....
}

Now you can use the interface in your method

private void subMenu(String item) {
    InterfaceName obj;

    switch(item) {
        case "employee":
            obj = new Employee();
            break;
        case "article":
            obj = new Article();
            break;
    }
    obj.edit();
    obj.remove();
    ...
}

Upvotes: 2

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