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Java example source code file (TypeVisitorTest.java)

This example Java source code file (TypeVisitorTest.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

basetypevisitor, enum, override, parameterizedtype, reflection, testcase, type, typecapture, typevisitortest, unsupportedoperationexception, util, wildcardtype

The TypeVisitorTest.java Java example source code

/*
 * Copyright (C) 2013 The Guava Authors
 *
 * 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.common.reflect;

import junit.framework.TestCase;

import java.lang.reflect.GenericArrayType;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.lang.reflect.WildcardType;
import java.util.ArrayList;
import java.util.EnumSet;

/**
 * Tests of {@link TypeVisitor}.
 *
 * @author Ben Yu
 */
public class TypeVisitorTest extends TestCase {

  public void testVisitNull() {
    new BaseTypeVisitor().visit(
        ((ParameterizedType) ArrayList.class.getGenericSuperclass()).getOwnerType());
  }

  public void testVisitClass() {
    assertVisited(String.class);
    new BaseTypeVisitor() {
      @Override void visitClass(Class<?> t) {}
    }.visit(String.class);
  }

  public <T> void testVisitTypeVariable() {
    Type type = new TypeCapture<T>() {}.capture();
    assertVisited(type);
    new BaseTypeVisitor() {
      @Override void visitTypeVariable(TypeVariable<?> t) {}
    }.visit(type);
  }

  public void testVisitWildcardType() {
    WildcardType type = Types.subtypeOf(String.class);
    assertVisited(type);
    new BaseTypeVisitor() {
      @Override void visitWildcardType(WildcardType t) {}
    }.visit(type);
  }

  public <T> void testVisitGenericArrayType() {
    Type type = new TypeCapture<T[]>() {}.capture();
    assertVisited(type);
    new BaseTypeVisitor() {
      @Override void visitGenericArrayType(GenericArrayType t) {}
    }.visit(type);
  }

  public <T> void testVisitParameterizedType() {
    Type type = new TypeCapture<Iterable() {}.capture();
    assertVisited(type);
    new BaseTypeVisitor() {
      @Override void visitParameterizedType(ParameterizedType t) {}
    }.visit(type);
  }

  public <E extends Enum void testVisitRecursiveTypeBounds() {
    Type type = new TypeCapture<EnumSet() {}.capture();
    assertVisited(type);
    new BaseTypeVisitor() {
      @Override void visitParameterizedType(ParameterizedType t) {
        visit(t.getActualTypeArguments());
      }
      @Override void visitTypeVariable(TypeVariable<?> t) {
        visit(t.getBounds());
      }
    }.visit(type);
  }

  private static void assertVisited(Type type) {
    TypeVisitor visitor = new BaseTypeVisitor();
    try {
      visitor.visit(type);
      fail("Type not visited");
    } catch (UnsupportedOperationException expected) {}
    try {
      visitor.visit(new Type[] {type});
      fail("Type not visited");
    } catch (UnsupportedOperationException expected) {}
  }

  private static class BaseTypeVisitor extends TypeVisitor {
    @Override void visitTypeVariable(TypeVariable<?> t) {
      throw new UnsupportedOperationException();
    }

    @Override void visitWildcardType(WildcardType t) {
      throw new UnsupportedOperationException();
    }

    @Override void visitParameterizedType(ParameterizedType t) {
      throw new UnsupportedOperationException();
    }

    @Override void visitClass(Class<?> t) {
      throw new UnsupportedOperationException();
    }

    @Override void visitGenericArrayType(GenericArrayType t) {
      throw new UnsupportedOperationException();
    }
  }
}

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