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Java example source code file (TypeLiteralTest.java)

This example Java source code file (TypeLiteralTest.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

charsequence, class, genericarraytype, hastypeparameters, ioexception, list, nosuchfieldexception, reflection, runnable, suppresswarnings, typeliteral, typeliteraltest, typevariable, util

The TypeLiteralTest.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 static com.google.inject.Asserts.assertEqualsBothWays;
import static com.google.inject.Asserts.assertNotSerializable;

import com.google.common.collect.ImmutableList;
import com.google.inject.util.Types;

import junit.framework.TestCase;

import java.io.IOException;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.List;

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

  public void testWithParameterizedType() {
    TypeLiteral<List a = new TypeLiteral>() {};
    TypeLiteral<List b = new TypeLiteral>(
        Types.listOf(String.class)) {};
    assertEqualsBothWays(a, b);
  }

  public void testEquality() {
    TypeLiteral<List t1 = new TypeLiteral>() {};
    TypeLiteral<List t2 = new TypeLiteral>() {};
    TypeLiteral<List t3 = new TypeLiteral>() {};
    TypeLiteral<String> t4 = new TypeLiteral() {};

    assertEqualsBothWays(t1, t2);

    assertFalse(t2.equals(t3));
    assertFalse(t3.equals(t2));

    assertFalse(t2.equals(t4));
    assertFalse(t4.equals(t2));

    TypeLiteral<String> t5 = TypeLiteral.get(String.class);
    assertEqualsBothWays(t4, t5);
  }

  public List<? extends CharSequence> wildcardExtends;

  public void testWithWildcardType() throws NoSuchFieldException, IOException {
    TypeLiteral<?> a = TypeLiteral.get(getClass().getField("wildcardExtends").getGenericType());
    TypeLiteral<?> b = TypeLiteral.get(Types.listOf(Types.subtypeOf(CharSequence.class)));
    TypeLiteral<?> c = new TypeLiteral>() {};
    assertEqualsBothWays(a, b);
    assertEqualsBothWays(b, c);
    assertEquals("java.util.List<? extends java.lang.CharSequence>", a.toString());
    assertEquals("java.util.List<? extends java.lang.CharSequence>", b.toString());
    assertEquals("java.util.List<? extends java.lang.CharSequence>", c.toString());
    assertNotSerializable(a);
    assertNotSerializable(b);
    assertNotSerializable(c);
  }

  public void testMissingTypeParameter() {
    try {
      new TypeLiteral() {};
      fail();
    } catch (RuntimeException e) { /* expected */ }
  }

  public void testTypesInvolvingArraysForEquality() {
    TypeLiteral<String[]> stringArray = new TypeLiteral() {};
    assertEquals(stringArray, new TypeLiteral<String[]>() {});

    TypeLiteral<List listOfStringArray
        = new TypeLiteral<List() {};
    assertEquals(listOfStringArray, new TypeLiteral<List() {});
  }

  public void testEqualityOfGenericArrayAndClassArray() {
    TypeLiteral<String[]> arrayAsClass = TypeLiteral.get(String[].class);
    TypeLiteral<String[]> arrayAsType = new TypeLiteral() {};
    assertEquals(arrayAsClass, arrayAsType);
  }

  public void testEqualityOfMultidimensionalGenericArrayAndClassArray() {
    TypeLiteral<String[][][]> arrayAsClass = TypeLiteral.get(String[][][].class);
    TypeLiteral<String[][][]> arrayAsType = new TypeLiteral() {};
    assertEquals(arrayAsClass, arrayAsType);
  }

  public void testTypeLiteralsMustHaveRawTypes() {
    try {
      TypeLiteral.get(Types.subtypeOf(Runnable.class));
      fail();
    } catch (IllegalArgumentException expected) {
      Asserts.assertContains(expected.getMessage(), "Expected a Class, ParameterizedType, or "
          + "GenericArrayType, but <? extends java.lang.Runnable> is of type "
          + "com.google.inject.internal.MoreTypes$WildcardTypeImpl");
    }
  }

  /**
   * Unlike Key, TypeLiteral retains full type information and differentiates
   * between {@code int.class} and {@code Integer.class}.
   */
  public void testDifferentiationBetweenWrappersAndPrimitives() {
    Class[] primitives = new Class[] {
        boolean.class, byte.class, short.class, int.class, long.class,
        float.class, double.class, char.class, void.class
    };
    Class[] wrappers = new Class[] {
        Boolean.class, Byte.class, Short.class, Integer.class, Long.class,
        Float.class, Double.class, Character.class, Void.class
    };

    for (int t = 0; t < primitives.length; t++) {
      @SuppressWarnings("unchecked")
      TypeLiteral primitiveTl = TypeLiteral.get(primitives[t]);
      @SuppressWarnings("unchecked")
      TypeLiteral wrapperTl = TypeLiteral.get(wrappers[t]);

      assertFalse(primitiveTl.equals(wrapperTl));
      assertEquals(primitives[t], primitiveTl.getType());
      assertEquals(wrappers[t], wrapperTl.getType());
      assertEquals(primitives[t], primitiveTl.getRawType());
      assertEquals(wrappers[t], wrapperTl.getRawType());
    }
  }

  public void testSerialization() throws IOException {
    assertNotSerializable(new TypeLiteral<List() {});
  }

  public void testTypeVariableWithNoBound() {
    TypeVariable<Class[] typeVariables
        = HasTypeParameters.class.getTypeParameters();

    TypeLiteral<?> aTl = TypeLiteral.get(typeVariables[0]);
    assertEquals(Object.class, aTl.getRawType());
    assertEquals("A", aTl.toString());
    TypeVariable<?> aTv = (TypeVariable) aTl.getType();
    assertEquals(HasTypeParameters.class, aTv.getGenericDeclaration());
    assertEquals("A", aTv.getName());
    assertEquals(ImmutableList.<Type>of(Object.class), ImmutableList.copyOf(aTv.getBounds()));
    assertEquals("A", aTv.toString());
    assertEqualsBothWays(aTl, TypeLiteral.get(HasTypeParameters.class.getTypeParameters()[0]));
  }

  public void testTypeVariablesWithSingleBound() {
    TypeVariable<Class[] typeVariables
        = HasTypeParameters.class.getTypeParameters();

    TypeLiteral<?> cTl = TypeLiteral.get(typeVariables[2]);
    assertEquals(Object.class, cTl.getRawType());
    assertEquals("C", cTl.toString());
    TypeVariable<?> cTv = (TypeVariable) cTl.getType();
    assertEquals(HasTypeParameters.class, cTv.getGenericDeclaration());
    assertEquals("C", cTv.getName());
    assertEquals(ImmutableList.<Type>of(Runnable.class), ImmutableList.copyOf(cTv.getBounds()));
    assertEquals("C", cTv.toString());
    assertEqualsBothWays(cTl, TypeLiteral.get(HasTypeParameters.class.getTypeParameters()[2]));
  }

  public void testTypeVariableWithMultipleBounds() {
    TypeVariable<Class[] typeVariables
        = HasTypeParameters.class.getTypeParameters();

    TypeLiteral<?> bTl = TypeLiteral.get(typeVariables[1]);
    assertEquals(Object.class, bTl.getRawType());
    assertEquals("B", bTl.toString());
    TypeVariable<?> bTv = (TypeVariable) bTl.getType();
    assertEquals(HasTypeParameters.class, bTv.getGenericDeclaration());
    assertEquals("B", bTv.getName());
    assertEquals(ImmutableList.<Type>of(Types.listOf(typeVariables[0]), Runnable.class),
        ImmutableList.copyOf(bTv.getBounds()));
    assertEquals("B", bTv.toString());
    assertEqualsBothWays(bTl, TypeLiteral.get(HasTypeParameters.class.getTypeParameters()[1]));
  }

  class HasTypeParameters<A, B extends List {
    A a; B b; C c;
  }
}

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