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Groovy example source code file (ToString.java)

This example Groovy source code file (ToString.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

annotation, groovyasttransformationclass, groovyasttransformationclass, string, string, target, target, tostring, tostring

The Groovy ToString.java source code

/*
 * Copyright 2008-2011 the original author or 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 groovy.transform;

import org.codehaus.groovy.transform.GroovyASTTransformationClass;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Class annotation used to assist in the creation of {@code toString()} methods in classes.
 * The {@code @ToString} annotation instructs the compiler to execute an
 * AST transformation which adds the necessary toString() method.
 * <p/>
 * It allows you to write classes in this shortened form:
 * <pre>
 * {@code @ToString}
 * class Customer {
 *     String first, last
 *     int age
 *     Date since = new Date()
 *     Collection favItems
 *     private answer = 42
 * }
 * println new Customer(first:'Tom', last:'Jones', age:21, favItems:['Books', 'Games'])
 * </pre>
 * Which will have this output:
 * <pre>
 * Customer(Tom, Jones, 21, Wed Jul 14 23:57:14 EST 2010, [Books, Games])
 * </pre>
 * There are numerous options to customize the format of the generated output.
 * E.g. if you change the first annotation to:
 * <pre>
 * {@code @ToString(includeNames=true)}
 * </pre>
 * Then the output will be:
 * <pre>
 * Customer(first:Tom, last:Jones, age:21, since:Wed Jul 14 23:57:50 EST 2010, favItems:[Books, Games])
 * </pre>
 * Or if you change the first annotation to:
 * <pre>
 * {@code @ToString(includeNames=true,includeFields=true,excludes="since,favItems")}
 * </pre>
 * Then the output will be:
 * <pre>
 * Customer(first:Tom, last:Jones, age:21, answer:42)
 * </pre>
 * If you have this example:
 * <pre>
 * import groovy.transform.ToString
 * {@code @ToString} class NamedThing {
 *     String name
 * }
 * {@code @ToString}(includeNames=true,includeSuper=true)
 * class AgedThing extends NamedThing {
 *     int age
 * }
 * println new AgedThing(name:'Lassie', age:5)
 * </pre>
 * Then the output will be:
 * <pre>
 * AgedThing(age:5, super:NamedThing(Lassie))
 * </pre>
 *
 * @author Paul King
 * @since 1.8.0
 */
@java.lang.annotation.Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
@GroovyASTTransformationClass("org.codehaus.groovy.transform.ToStringASTTransformation")
public @interface ToString {
    /**
     * Comma separated list of field and/or property names to exclude from generated toString.
     * Must not be used if 'includes' is used.
     */
    String excludes() default "";

    /**
     * Comma separated list of field and/or property names to include within the generated toString.
     * Must not be used if 'excludes' is used.
     */
    String includes() default "";

    /**
     * Whether to include super in generated toString
     */
    boolean includeSuper() default false;

    /**
     * Whether to include names of properties/fields in generated toString
     */
    boolean includeNames() default false;

    /**
     * Include fields as well as properties in generated toString
     */
    boolean includeFields() default false;
}

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