001    /*
002     * Created on Aug 17, 2007
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005     * in compliance with the License. You may obtain a copy of the License at
006     *
007     * http://www.apache.org/licenses/LICENSE-2.0
008     *
009     * Unless required by applicable law or agreed to in writing, software distributed under the License
010     * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
011     * or implied. See the License for the specific language governing permissions and limitations under
012     * the License.
013     *
014     * Copyright @2007-2009 the original author or authors.
015     */
016    package org.fest.reflect.method;
017    
018    import static org.fest.reflect.method.Invoker.newInvoker;
019    import static org.fest.reflect.method.MethodParameterTypes.newParameterTypes;
020    import static org.fest.reflect.method.MethodReturnType.newReturnType;
021    import static org.fest.reflect.method.MethodReturnTypeRef.newReturnTypeRef;
022    import static org.fest.util.Strings.isEmpty;
023    
024    import org.fest.reflect.reference.TypeRef;
025    
026    
027    
028    /**
029     * Understands the name of a method to invoke using Java Reflection.
030     * <p>
031     * The following is an example of proper usage of this class:
032     * <pre>
033     *   // Equivalent to call 'person.setName("Luke")'
034     *   {@link org.fest.reflect.core.Reflection#method(String) method}("setName").{@link MethodName#withParameterTypes(Class...) withParameterTypes}(String.class)
035     *                    .{@link MethodParameterTypes#in(Object) in}(person)
036     *                    .{@link Invoker#invoke(Object...) invoke}("Luke");
037     *
038     *   // Equivalent to call 'person.concentrate()'
039     *   {@link org.fest.reflect.core.Reflection#method(String) method}("concentrate").{@link MethodName#in(Object) in}(person).{@link Invoker#invoke(Object...) invoke}();
040     *
041     *   // Equivalent to call 'person.getName()'
042     *   String name = {@link org.fest.reflect.core.Reflection#method(String) method}("getName").{@link MethodName#withReturnType(Class) withReturnType}(String.class)
043     *                                  .{@link MethodReturnType#in(Object) in}(person)
044     *                                  .{@link Invoker#invoke(Object...) invoke}();
045     *
046     *   // Equivalent to call 'jedi.getPowers()'
047     *   List&lt;String&gt; powers = {@link org.fest.reflect.core.Reflection#method(String) method}("getPowers").{@link MethodName#withReturnType(TypeRef) withReturnType}(new {@link TypeRef TypeRef}&lt;List&lt;String&gt;&gt;() {})
048     *                                            .{@link MethodReturnTypeRef#in(Object) in}(person)
049     *                                            .{@link Invoker#invoke(Object...) invoke}();
050     * </pre>
051     * </p>
052     *
053     * @author Yvonne Wang
054     * @author Alex Ruiz
055     */
056    public final class MethodName {
057    
058      /**
059       * Creates a new <code>{@link MethodName}</code>: the starting point of the fluent interface for accessing methods
060       * using Java Reflection.
061       * @param name the name of the method to invoke using Java Reflection.
062       * @return the created <code>MethodName</code>.
063       * @throws NullPointerException if the given name is <code>null</code>.
064       * @throws IllegalArgumentException if the given name is empty.
065       */
066      public static MethodName startMethodAccess(String name) {
067        validateIsNotNullOrEmpty(name);
068        return new MethodName(name);
069      }
070    
071      private static void validateIsNotNullOrEmpty(String name) {
072        if (name == null)
073          throw new NullPointerException("The name of the method to access should not be null");
074        if (isEmpty(name))
075          throw new IllegalArgumentException("The name of the method to access should not be empty");
076      }
077    
078      private final String name;
079    
080      private MethodName(String name) {
081        this.name = name;
082      }
083    
084      /**
085       * Specifies the return type of the method to invoke. This method call is optional if the return type of the method to
086       * invoke is <code>void</code>.
087       * @param <T> the generic type of the method's return type.
088       * @param type the return type of the method to invoke.
089       * @return the created return type holder.
090       * @throws NullPointerException if the given type is <code>null</code>.
091       */
092      public <T> MethodReturnType<T> withReturnType(Class<T> type) {
093        return newReturnType(name, type);
094      }
095    
096      /**
097       * Specifies the return type reference of the method to invoke. This method call is optional if the return type of the
098       * method to invoke is <code>void</code>.
099       * @param <T> the generic type of the method's return type.
100       * @param type the return type reference of the method to invoke.
101       * @return the created return type holder.
102       * @throws NullPointerException if the given type reference is <code>null</code>.
103       * @since 1.1
104       */
105      public <T> MethodReturnTypeRef<T> withReturnType(TypeRef<T> type) {
106        return newReturnTypeRef(name, type);
107      }
108    
109      /**
110       * Specifies the parameter types of the method to invoke. This method call is optional if the method to invoke does
111       * not take arguments.
112       * @param parameterTypes the parameter types of the method to invoke.
113       * @return the created parameter types holder.
114       * @throws NullPointerException if the array of parameter types is <code>null</code>.
115       */
116      public MethodParameterTypes<Void> withParameterTypes(Class<?>... parameterTypes) {
117        return newParameterTypes(name, parameterTypes);
118      }
119    
120      /**
121       * Creates a new invoker for a method that takes no parameters and return value <code>void</code>.
122       * @param target the object containing the method to invoke.
123       * @return the created method invoker.
124       * @throws NullPointerException if the given target is <code>null</code>.
125       */
126      public Invoker<Void> in(Object target) {
127        return newInvoker(name, target);
128      }
129    }