Java example source code file (Classes.java)

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Java - Java tags/keywords

assertionerror, class, classes, constructor, field, illegalargumentexception, member, method, reflection, string, unsupported

The Classes.java Java example source code

/**
 * Copyright (C) 2007 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.internal.util;

import static com.google.common.base.Preconditions.checkNotNull;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

/**
 * Class utilities.
 */
public final class Classes {

  public static boolean isInnerClass(Class<?> clazz) {
    return !Modifier.isStatic(clazz.getModifiers())
        && clazz.getEnclosingClass() != null;
  }

  public static boolean isConcrete(Class<?> clazz) {
    int modifiers = clazz.getModifiers();
    return !clazz.isInterface() && !Modifier.isAbstract(modifiers);
  }

  /**
   * Formats a member as concise string, such as {@code java.util.ArrayList.size},
   * {@code java.util.ArrayList<init>()} or {@code java.util.List.remove()}.
   */
  public static String toString(Member member) {
    Class<? extends Member> memberType = Classes.memberType(member);
  
    if (memberType == Method.class) {
      return member.getDeclaringClass().getName() + "." + member.getName() + "()";
    } else if (memberType == Field.class) {
      return member.getDeclaringClass().getName() + "." + member.getName();
    } else if (memberType == Constructor.class) {
      return member.getDeclaringClass().getName() + ".<init>()";
    } else {
      throw new AssertionError();
    }
  }

  /**
   * Returns {@code Field.class}, {@code Method.class} or {@code Constructor.class}.
   */
  public static Class<? extends Member> memberType(Member member) {
    checkNotNull(member, "member");
  
    if (member instanceof Field) {
      return Field.class;
  
    } else if (member instanceof Method) {
      return Method.class;
  
    } else if (member instanceof Constructor) {
      return Constructor.class;
  
    } else {
      throw new IllegalArgumentException(
          "Unsupported implementation class for Member, " + member.getClass());
    }
  }
}