Access object created in one class into another

I have a primary class as below:

public class classB{
 
   public classC getObject(String getstring){
      return new classC(getstring);
     }
 }
 

The classC has a contructor:

public class classC{
 
  String string;
 
  public classC(String s){
   this.string = s;
  }
 
  public methodC(int i){
    <using the `string` variable here>
  }
 }
 

Now I've a classA which will be using the object created in classB(which is of course, an instance of classC).

public classA{
   int a = 0.5;
 
   <Get the object that was created in classB>.methodC(a);
 
 }
 

This is needed as a variable is created on some actions from the user and stored in classB and this would be further used in classC's methods. Creating a new object will render my variable in classB set to null which isn't intended.

How can I achieve this?

Please help!

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