In this section you will learn how to create and use type safe templates in Handlebars.java.

TypeSafe templates are created by extending theTypeSafeTemplateinterface

public interface TypeSafeTemplate<T> {

  void apply(T context, Writer writer) throws IOException;

  String apply(T context) throws IOException;
}

TheTypeSafeTemplateinterface give you a generic version of theapplymethods, but this isn't all.

Creating a type safe template

public interface UserTemplate extends TypeSafeTemplate<User> {

  public UserTemplate setAge(int age);

  public UserTemplate setRole(String role);
}

UserTemplate userTmpl = hbs.compileInline("{{name}} is {{age}} years old!")
  .as(UserTemplate.class);

userTmpl.setAge(32);

userTmpl.apply(new User("Edgar"));

Checking if a variable is present

Beside we have asetAgemethod how can we sure that value has been provided? One alternative, is to provide aMissingValueResolverto fail ifageisn't present.

MissingValueResolver missingValueResolver = new MissingValueResolver() {
    public String resolve(Object context, String name) {
      throw new IllegalStateException("Missing variable: " + name);
    }
  };
Handlebars hbs = new Handlebars().with(missingValueResolver);

UserTemplate userTmpl = hbs.compileInline("{{name}} is {{age}} years old!")
  .as(UserTemplate.class);

userTmpl.setAge(32);

userTmpl.apply(new User("Edgar"));

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