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Java example source code file (GenericInjectionTest.java)

This example Java source code file (GenericInjectionTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractmodule, foo, inject, injector, injectst, integer, key, list, long, map, parameterizeddeps, provides, set, typeliteral, util

The GenericInjectionTest.java Java example source code

/**
 * Copyright (C) 2006 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.inject;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.inject.util.Modules;

import junit.framework.TestCase;

import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * @author crazybob@google.com (Bob Lee)
 */
public class GenericInjectionTest extends TestCase {

  public void testGenericInjection() throws CreationException {
    final List<String> names = Arrays.asList("foo", "bar", "bob");

    Injector injector = Guice.createInjector((Module) new AbstractModule() {
      protected void configure() {
        bind(new TypeLiteral<List() {}).toInstance(names);
      }
    });

    Foo foo = injector.getInstance(Foo.class);
    assertEquals(names, foo.names);
  }

  static class Foo {
    @Inject List<String> names;
  }

  /**
   * Although we may not have intended to support this behaviour, this test
   * passes under Guice 1.0. The workaround is to add an explicit binding for
   * the parameterized type. See {@link #testExplicitBindingOfGenericType()}.
   */
  public void testImplicitBindingOfGenericType() {
    Parameterized<String> parameterized
        = Guice.createInjector().getInstance(Key.get(new TypeLiteral<Parameterized() {}));
    assertNotNull(parameterized);
  }

  public void testExplicitBindingOfGenericType() {
    Injector injector = Guice.createInjector(new AbstractModule() {
      protected void configure() {
        bind(Key.get(new TypeLiteral<Parameterized() {}))
            .to((Class) Parameterized.class);
      }
    });

    Parameterized<String> parameterized
        = injector.getInstance(Key.get(new TypeLiteral<Parameterized() { }));
    assertNotNull(parameterized);
  }

  static class Parameterized<T> {
    @Inject
    Parameterized() { }
  }

  public void testInjectingParameterizedDependenciesForImplicitBinding() {
    assertParameterizedDepsInjected(new Key<ParameterizedDeps() {},
        Modules.EMPTY_MODULE);
  }

  public void testInjectingParameterizedDependenciesForBindingTarget() {
    final TypeLiteral<ParameterizedDeps type
        = new TypeLiteral<ParameterizedDeps() {};

    assertParameterizedDepsInjected(Key.get(Object.class), new AbstractModule() {
      protected void configure() {
        bind(Object.class).to(type);
      }
    });
  }

  public void testInjectingParameterizedDependenciesForBindingSource() {
    final TypeLiteral<ParameterizedDeps type
        = new TypeLiteral<ParameterizedDeps() {};

    assertParameterizedDepsInjected(Key.get(type), new AbstractModule() {
      protected void configure() {
        bind(type);
      }
    });
  }

  public void testBindingToSubtype() {
    final TypeLiteral<ParameterizedDeps type
        = new TypeLiteral<ParameterizedDeps() {};

    assertParameterizedDepsInjected(Key.get(type), new AbstractModule() {
      protected void configure() {
        bind(type).to(new TypeLiteral<SubParameterizedDeps() {});
      }
    });
  }

  public void testBindingSubtype() {
    final TypeLiteral<SubParameterizedDeps type
        = new TypeLiteral<SubParameterizedDeps() {};

    assertParameterizedDepsInjected(Key.get(type), new AbstractModule() {
      protected void configure() {
        bind(type);
      }
    });
  }

  @SuppressWarnings("unchecked")
  public void assertParameterizedDepsInjected(Key<?> key, Module bindingModule) {
    Module bindDataModule = new AbstractModule() {
      protected void configure() {}
      @Provides Map<String, Integer> provideMap() {
        return ImmutableMap.of("one", 1, "two", 2);
      }
      @Provides Set<String> provideSet(Map map) {
        return map.keySet();
      }
      @Provides Collection<Integer> provideCollection(Map map) {
        return map.values();
      }
    };

    Injector injector = Guice.createInjector(bindDataModule, bindingModule);
    ParameterizedDeps<String, Integer> parameterizedDeps
        = (ParameterizedDeps<String, Integer>) injector.getInstance(key);
    assertEquals(ImmutableMap.of("one", 1, "two", 2), parameterizedDeps.map);
    assertEquals(ImmutableSet.of("one", "two"), parameterizedDeps.keys);
    assertEquals(ImmutableSet.of(1, 2), ImmutableSet.copyOf(parameterizedDeps.values));
  }

  static class SubParameterizedDeps<A, B, C> extends ParameterizedDeps {
    @Inject SubParameterizedDeps(Set<A> keys) {
      super(keys);
    }
  }

  static class ParameterizedDeps<K, V> {
    @Inject private Map<K, V> map;
    private Set<K> keys;
    private Collection<V> values;

    @Inject ParameterizedDeps(Set<K> keys) {
      this.keys = keys;
    }

    @Inject void method(Collection<V> values) {
      this.values = values;
    }
  }

  public void testImmediateTypeVariablesAreInjected() {
    Injector injector = Guice.createInjector(new AbstractModule() {
      protected void configure() {
        bind(String.class).toInstance("tee");
      }
    });
    InjectsT<String> injectsT = injector.getInstance(new Key>() {});
    assertEquals("tee", injectsT.t);
  }

  static class InjectsT<T> {
    @Inject T t;
  }
}

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