How to overload a method by method with parameters list that contains parameters of the exact same type but parametrized with other types

Question

I have a methods:

public List convertBy(Function> flines, Function, String> join, Fu         


        

Answer 1

If you want to create a method which applies multiple functions and is not interested in the intermediate values, you can make it a generic method. The code in your question is strange as it assumes that value can be a String and a List at the same time.

But comparing with your other question, there’s a different picture. While the varargs method there can’t work that way, you can easily provide overloaded methods for the actual use cases:

public class InputConverter {

    private T value;

    public InputConverter(T value) {
        this.value = value;
    }
    public  R convertBy(Function f) {
        return f.apply(value);
    }
    public  R convertBy(
        Function f1, Function f2) {
        return f2.apply(f1.apply(value));
    }
    public  R convertBy(
        Function f1, Function f2,
        Function f3) {
        return f3.apply(f2.apply(f1.apply(value)));
    }
    public  R convertBy(
        Function f1, Function f2,
        Function f3, Function f4) {
        return f4.apply(f3.apply(f2.apply(f1.apply(value))));
    }
}

Assuming that you fixed your interface types and created functions as described in this answer, you can use it like

InputConverter fileConv=new InputConverter<>("LamComFile.txt");
List lines = fileConv.convertBy(flines);
String text = fileConv.convertBy(flines, join);
List ints = fileConv.convertBy(flines, join, collectInts);
Integer sumints = fileConv.convertBy(flines, join, collectInts, sum);