How would I overload method in an interface?

Question

if I have this interface

public interface someInterface {
  // method 1
  public String getValue(String arg1);
  // method 2
  public String getValue(String arg1         


        

Answer 1

As of Java 8, you can have an interface provide an implementation of a method, through the use of the default keyword. Therefore a new solution would be to provide a default implementation of both methods which maybe throws an exception, then derive the actual implementation from the default interface.

Anyways here is how you can do this:

public interface SomeInterface {
    // method 1
    default String getValue(String arg1) {
        // you decide what happens with this default implementation
    }

    // method 2
    default String getValue(String arg1, String arg2) {
        // you decide what happens with this default implementation
    }
}

Finally, make the classes override the correct methods

public class SomeClass1 implements SomeInterface {
    @Override
    public String getValue(String arg1) {
        return arg1;
    }
}

public class SomeClass2 implements SomeInterface {
    @Override
    public String getValue(String arg1, String arg2) {
        return arg1 + " " + arg2;
    }
}