Run time instance creation of sub classes in template design pattern

I am creating an application which has three algorithms with some common piece of code . Hence i decided to go with Template Design Pattern. I need to decide the algorithm to be called at runtime like below

switch(filetype){
case "test":
BaseClass b = new SubClass1();
b.convert();

case "test2":
BaseClass b = new SubClass12();
b.convert();
}

i want to avoid the switch case while instance creation during run time and want to use Dependency injection to achieve the same. Could you suggest any pattern to achieve this.