How to declear a list variable of specific class base on classname in java

description:

• I need declear a list maybe bound mutiple types.One type in each run.

pseudo-code：

// first run
String Type = "Foo";
List<Type> results = new ArrayList<Type>();// want to declear a `List<Foo>` variable here
// second run
String Type = "Bar";
List<Type> results = new ArrayList<Type>();// want to declear a `List<Bar>` variable here

what I have tried:

1. use switch

Foo.java
public class Foo {
}
Bar.java
public class Bar {
}
test.java

public class test{
    public static void main(String[] args) {
        String type = "Bar";
        switch (type){
            case "Bar":
                List<Bar> barResults = new ArrayList<>();
                Bar tempBar = new Bar();
                barResults.add(tempBar);
                System.out.println(barResults);
                break;
            case "Foo":
                List<Foo> fooResults = new ArrayList<>();
                Foo tempFoo = new Foo();
                fooResults.add(tempFoo);
                System.out.println(fooResults);
                break;
        }
    }

• I think it works (not 100% comfirmed), but it will cause a lot of duplicated code.

2. Use reflection and extract a function

public class test{
    public static void main(String[] args) {
        try {
            Class<?> type = Class.forName("Bar");
            List<?> result = new test().mytry(type);
            System.out.println(result);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
    }
    public List<?> mytry(Class<?> classname) {
        List<Object> results = new ArrayList<>();
        try {
            Object obj = classname.getDeclaredConstructor().newInstance();
            results.add(obj);
            return results;
        } catch ( NoSuchMethodException | InstantiationException | IllegalAccessException | InvocationTargetException e) {
            e.printStackTrace();
        }
        return null;
    }
}

• I can't comfirm whether it works or not.

3. Use map

• (In progress)

question:

• How to declear a list of specific class base on classname?