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/*
* Copyright (C) 2014 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.gson.internal;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.fail;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;
import org.junit.Test;
public final class GsonTypesTest {
@Test
public void testNewParameterizedTypeWithoutOwner() throws Exception {
// List<A>. List is a top-level class
Type type = $Gson$Types.newParameterizedTypeWithOwner(null, List.class, A.class);
assertEquals(A.class, getFirstTypeArgument(type));
// A<B>. A is a static inner class.
type = $Gson$Types.newParameterizedTypeWithOwner(null, A.class, B.class);
assertEquals(B.class, getFirstTypeArgument(type));
final class D {
}
try {
// D<A> is not allowed since D is not a static inner class
$Gson$Types.newParameterizedTypeWithOwner(null, D.class, A.class);
fail();
} catch (IllegalArgumentException expected) {}
// A<D> is allowed.
type = $Gson$Types.newParameterizedTypeWithOwner(null, A.class, D.class);
assertEquals(D.class, getFirstTypeArgument(type));
}
@Test
public void testGetFirstTypeArgument() throws Exception {
assertNull(getFirstTypeArgument(A.class));
Type type = $Gson$Types.newParameterizedTypeWithOwner(null, A.class, B.class, C.class);
assertEquals(B.class, getFirstTypeArgument(type));
}
private static final class A {
}
private static final class B {
}
private static final class C {
}
/**
* Given a parameterized type A<B,C>, returns B. If the specified type is not
* a generic type, returns null.
*/
public static Type getFirstTypeArgument(Type type) throws Exception {
if (!(type instanceof ParameterizedType)) return null;
ParameterizedType ptype = (ParameterizedType) type;
Type[] actualTypeArguments = ptype.getActualTypeArguments();
if (actualTypeArguments.length == 0) return null;
return $Gson$Types.canonicalize(actualTypeArguments[0]);
}
}
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