需要帮助以避免类型转换

Question

I need help in refactoring the following piece of code . There are 2 main problems that I want to fix in this code 1. Unsafe type casting in Rule1 implementation 2. Implementation of too many interfaces

  public interface Rule {
     public void execute(DataProvider dataProvider);
  }

  public interface DataProvider {
     // No common functions as of now 
  }

  public interface Rule1dataProvider extends DataProvider {
     // Functions required by Rule1
  }

  public class Rule1 implements Rule {
     public void execute(DataProvider dataProvider) {
       ADataProvider rule1DataProvider = <ADataProvider>dataProvider;
       // Other logic 
    }
  }

 public class EntityADataProvider implements Rule1DataProvider, Rule2DataProvider... {
    // Overrides functions of Rule 1 and Rule2 
 }

I was trying to use generics here, but could not figure out the right way to use them in order to eliminate the type casting

Answer 1

Make Rule generic:

public interface Rule<T extends DataProvider> {
    public void execute(T dataProvider);
}

And then

public class Rule1 implements Rule<Rule1dataProvider> {
    @Override
    public void execute(Rule1dataProvider dataProvider) {            
        // ...
    }
}