Passing 1 to many parameters of same object type

问题

I need to build a set of input for different workflows using 1 or more outputs from previous workflows, when i do this

public interface InputBuilder<I extends SwfInput, O extends SwfOutput> {

    public I buildInput(O... output);
}


public class SwfAuthorisationInputBuilder implements InputBuilder {

    @Override
    public SwfAuthorisationInput buildInput(SwfOutput swfEventInitOutput) {

        SwfEventInitOutput output = (SwfEventInitOutput ) swfEventInitOutput;
        SwfAuthorisationInput authorisationInput = oddFactory.newInstance(SwfAuthorisationInput.class);
        authorisationInput.setNetworkEvent(output.getNetworkEvent());

        return authorisationInput;
    } 

I am getting and error and Netbeans tip fix gives me this. What am i doing wrong here ?

  @Override
        public SwfInput buildInput(SwfOutput... output) {
            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
        }

this is the exact error

method does not override or implement a method from a supertype

How can i avoid casting here ?

  @Override
        public SwfAuthorisationInput buildInput(SwfOutput... output) {
            SwfEventInitOutput swfEventInitOutput = (SwfEventInitOutput ) output[0];
            SwfLocationDetectionOutput swfLocationDetectionOutput = (SwfLocationDetectionOutput) output[1];


            SwfAuthorisationInput authorisationInput = oddFactory.newInstance(SwfAuthorisationInput.class);
            authorisationInput.setNetworkEvent(swfEventInitOutput.getNetworkEvent());

            return authorisationInput;
        }

回答1:

buildInput(SwfOutput swfEventInitOutput)

and

buildInput(SwfOutput... swfEventInitOutput)

are the different method signatures (the method's name and the parameter types in Java). If you want to override a method, you have to exactly * specify a signature from the parent class.

---

As I can see, you need only one element of this array. If so, you could pull out it from the array checking the array's size before:

swfEventInitOutput element = swfEventInitOutput.length > 0 ? swfEventInitOutput[0] : null;
if(element != null) { ... }

Another way is to iterate over the array and perform such actions for an each element:

for (swfEventInitOutput element : swfEventInitOutput) { ... }

---

In addition, I would suggest you specify generic types when you're implementing the InputBuilder interface. It helps you to avoid castings (which you did) inside overridden methods.

A positive side here is that you used bounded generics types, it has prevented from Object... (or Object[]).

来源：https://stackoverflow.com/questions/39768434/passing-1-to-many-parameters-of-same-object-type