Question

I am relatively inexperienced with java & generics, so please excuse me if this is a stupid question.

I have 3 very similar helper methods called verifyTextualSort, verifyNumericSort and verifyDateSort.

The 3 methods follow the same pattern with only a slight difference in them:

private boolean verifyTextualSort(...) {

    ArrayList<String> list = new ArrayList<String>();

    // Do common stuff with the list

    // Do textual-specific stuff 

    // Do common stuff with the list

}

private boolean verifyNumericSort(...) {

    ArrayList<Integer> list = new ArrayList<Integer>();

    // Do common stuff with the list

    // Do Numeric-specific stuff

    // Do common stuff with the list

}

Is there some way I can combine them into one method, passing somehow the type (Integer, String, Date) as a parameter? I have to be able to know which is the type from inside the method so that I can do the correct specific stuff.

Answer 1

You could pass a Class as a parameter, if that is what you want (as you said, passing the type as a parameter):

public <T> void test(List<T> l, T t, Class<T> c) {
    System.out.println(c.getName());
    System.out.println(l.get(0).getClass().getName());
    System.out.println(t.getClass().getName());
}

All the sysouts above will print out the name of the class, so you’ll be able to choose which one suits you the best.