AbstractTemplate.java

public abstract class AbstractTemplate {

    protected abstract String getTemplateFile();

    public String run() {
        return "rendered template from " + getTemplateFile();
    }

}

PartialTemplate.java

public class PartialTemplate extends AbstractTemplate {

    protected String getTemplateFile() {
        return "partial template file";
    }

}

Template.java

public class Template extends AbstractTemplate {

    protected String getTemplateFile() {
        return "full template file";
    }

}

Usage.java

public class Rendererer {

    public static void main() {
        assert(new Template().render(), "rendered template from full template file");
        assert(new PartialTemplate().render(), "rendered template from partial template file");
    }

}