How to retrieve annotated instance from Guice's injector?

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Solution 1

injector.getInstance(Key.get(String.class, Names.named("annotation")));

Solution 2

I'm using the following method

public <T> T getInstance(Class<T> type, Class<? extends Annotation> option) {
    final Key<T> key = Key.get(type, option);
    return injector.getInstance(key);
}

for this. In general, you still have the problem of creating the annotation instance, but here Names.named("annotation") works.

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Boris Pavlović
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Boris Pavlović

Interested in developing programming, concurrent model design skills, design patterns, refactoring, testing... Computer languages: java, javaScript, sql, fsp, erlang...

Updated on November 21, 2020

Comments

  • Boris Pavlović
    Boris Pavlović over 3 years

    Let's say I have a module:

    Module extends AbstractModule
    {
      @Override
      protected void configure()
      {
        bind(String.class).
          annotatedWith(Names.named("annotation")).
            toInstance("DELIRIOUS");
      }
    }
    

    and I want to test the module and check if it injects the right value in a String field annotated with Names.named("annotation") without having a class and a field but obtaining the value directly from the injector:

    @Test
    public void test()
    {
      Injector injector = Guice.createInjector(new Module());
    
      // THIS IS NOT GOING TO WORK!
      String delirious = injector.getInstance(String.class); 
    
      assertThat(delirious, IsEqual.equalTo("DELIRIOUS");
    }