如何将String映射到未知返回类型的java方法引用？

Question

I want to map a String to a method reference. The problem is that this method can return void or boolean .

I was using @FunctionalInterface but seems it can have only one method (I would need one for void and one for boolean ?).

Below is the code I have so far. The commented lines are what I would like to do.

@FunctionalInterface
interface MethodParser <T1, T2> {
    public void apply(T1 arg1, T2 arg2);
}

public class OperatorParser {

    public static Map<String, MethodParser> INTEGER = new HashMap<String, MethodParser>();

    public static void buildInteger() {
        MethodParser<Integer_, Integer> plus = (pObj, pValue) -> pObj.plus(pValue);
        MethodParser<Integer_, Integer> minus = (pObj, pValue) -> pObj.minus(pValue);

        // MethodParser<Integer_, Integer> grThan = (pObj, pValue) -> pObj.greaterThan(pValue);
        // MethodParser<Integer_, Integer> lessTh = (pObj, pValue) -> pObj.lessThan(pValue);

        OperatorParser.INTEGER.put("+", plus);
        OperatorParser.INTEGER.put("-", minus);

        // OperatorParser.INTEGER.put(">", grThan);
        // OperatorParser.INTEGER.put("<", lessTh);
    }

}

The object Integer_ represents a integer number and has void methods ( plus(int) and minus(int) ) that changes the value of the object and boolean methods ( greaterThan(int) and lessThan(int) ) that returns a value.

The MethodParser interface is just one way I found to map a String to a method reference. I use it to map a given String to a method that already exists somewhere else.

Note: Some similar questions I have tried (these don't worked for me):

• Can I map a String to a method in java?
• Return method reference

Answer 1

Make a method for void and one for boolean and a method that includes the condition that tells when to use either. I don't know of any method that could have 2 return types. You Can use a POJO class instance to return multiple values with grouping.