CODEWITHSUNDEEP
javaandroid
Delay
Delay

Reputation: 85

How to Copy class in java

My project consists of two classes: type 1 and type 2 is that each has its own functions and fields I'm gonna use them as follows:

private void initialize(String type) {
    if (type == "Type1") {
      x = new Type1;
    } else if (type == "Type2") {
      x = new Type2;
    }
}

What type of X variable must be ?

<Update 1>=============================

I use superclass and interface but I do not have access to variables and methods of type1 or type2 and only have access to variables and methods of the superclass

<Update 2>=============================

  public class Type1 extends SuperClass{
    public int var = 1;
  }

  public class Type2 extends SuperClass{
    public int var = 2;
  }

  private void initialize(String type) {
    switch (type) {
      case "Type1":
        x = new Type1();
        break;
      case "Type2":
        x = new Type2();
        break;
    }
  }

  void main(){
    //int num = x.var;
  }

In this case can not be used to cast : ((Type1)x).var

Upvotes: 3

Views: 719

Answers (6)

MSH
MSH

Reputation: 1297

Use an interface which will be implemented by both classes

public interface Typeimplemntor{}
public class Type1 implements Typeimplemntor{}
public class Type2 implements Typeimplemntor{}

After that in your function 

 private void initialize(String type) {
Typeimplemntor typImp;
        if (type == "Type1") {
          typImp = new Type1();
        } else if (type == "Type2") {
          typImp = new Type2();
        }
      }

Complete example for update

    public class Test {
        public static void main (String argd[])
        {
            String type= "Type2";
            Typeimplemntor typeimplemntor = null;
            if (type.equals("Type1")) {
                typeimplemntor = new Type1();
            }else if (type.equals("Type2")) {
                typeimplemntor = new Type2();
            }

            typeimplemntor.print();
            if (typeimplemntor instanceof Type1) {
                int y = ((Type1)typeimplemntor).x;
                System.out.println(y);
                ((Type1)typeimplemntor).notInInterfaceType1();
            }else if (typeimplemntor instanceof Type2){
                int y = ((Type2)typeimplemntor).x;
                System.out.println(y);
                ((Type2)typeimplemntor).notInInterfaceType2();
            }


        }
    }

public class Type1 implements Typeimplemntor {
    int x = 5;
    public void print () {
        System.out.println("Printed from Type1");
    }
   public void notInInterfaceType1 () {
    System.out.println("Not in interface but in Type1");
   }
}

public class Type2 implements Typeimplemntor {
    int x = 15;
    public void print () {
        System.out.println("Printed from Type2");
    }
    public void notInInterfaceType2 () {
       System.out.println("Not in interface but in Type2");
    }
}

public interface Typeimplemntor {
    void print();
}

If you have method which will be used in both the classes you can define them in interface and they can be accessed directly according to their implementation in classes. If there are some other methods or variables then you have to check the instance and then you have cast into the same.

Upvotes: 2

ΦXocę 웃 Пepe&#250;pa ツ
ΦXocę 웃 Пepe&#250;pa ツ

Reputation: 48287

if x is a variable that can hold both Type1 and Type2 then x could be:

  1. a superclass of both
  2. an interface that both classes are implementing

Example

Case 1

public class SuperType{}
public class Type1 extends SuperType{}
public class Type2 extends SuperType{}

then you can do

private void initialize(String type) {
    SuperType x = new Type1();
      //or
    SuperType x = new Type2();

  both are valid

Case 2

public interface IType{}
public class Type1 implements IType{}
public class Type2 implements IType{}

then you can do

private void initialize(String type) {
    IType x = new Type1();
      //or
    IType x = new Type2();

Edit

In both cases 1 and 2 x is a variable that can only invoke methods from Supertype or IType maybe you need Type1 specific methods then a casting is required

((Type1)x).myType1OnlyMethod ();

Upvotes: 1

Kamal Kunjapur
Kamal Kunjapur

Reputation: 8840

Just making a point, as long as you have control of modifying and writing Type1 and Type2, creating common interfaces should be fine.

However if you are making use of external classes where you do not have control of the source code, I'd suggest making use of Object reference.

Regardless ensure that you are aware of all the methods available in the classes and add appropriate type safety/casting feature wherever applicable.

Upvotes: 0

Andrew the Programmer
Andrew the Programmer

Reputation: 269

If you're defining a new object, it would have to be:

Type1 x = new Type1;
Type2 y = new Type2;

And then the constructor in those two classes will create that new object

If you are asking about inheritance, then it's a similar answer. You want to have your superclass (the class which gives some baseline variables that subclasses will have) and then you want to extend it to your two types. Roughly, it will look like this.

public class Type{
    private String exampleVariable;
    ...
}

public class Type1 extends Type{
    ...
}

public class Type2 extends Type{
    ...
}

And then you could create object via

Type a = new Type1();
Type b = new Type2();

Upvotes: 0

puneet yadav
puneet yadav

Reputation: 103

Do it like this

    If (Type instanceOf Type1) {
                                x = new Type1;
                              } 
   else if (Type instanceOf Type2)   {
                                x = new Type2;
                               }

Upvotes: 1

Mureinik
Mureinik

Reputation: 311798

If you want x to accept an instance of either Type1 or Type2, it must be some common ancestor or interface they both share. If you haven't declared such a type, you can always resort to Object, which is the common ancestor of all classes.

Upvotes: 0

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