Java pass method reference as parameter to other method

Question

I am trying to pass a selected \"get\"-method of class A to a method in class B. I have checked out Java Pass Method as Parameter, but I was not able to adopt the interface appr

Answer 1

Awhile ago I used java.util.concurrent.Callable but it doesn't seem to work out, thanks to @Eran.

Instead, you can use Java 8's java.util.function.Function, like so (without the lambdas):

public static void main(String[] args) {
 //...
    getValuesAsArray(dataMap, new Function(){ public Float apply(DataStore input) { return input.getA(); }});
    getValuesAsArray(dataMap, new Function(){ public Float apply(DataStore input) { return input.getB(); }});
    getValuesAsArray(dataMap, new Function(){ public Float apply(DataStore input) { return input.getC(); }});
}

private static float[] getValuesAsArray(Map dataMap, Function function) {
    int i = 0;
    int nMap = dataMap.size();
    float[] fArray = new float[nMap];
    for (Map.Entry entry : dataMap.entrySet()) {
        DataStore ds = entry.getValue();
        fArray[i] = function.apply(ds);
        i++;
    }
    return fArray;
}