/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.commons.lang3.builder;
The Builder interface is designed to designate a class as a builder
object in the Builder design pattern. Builders are capable of creating and
configuring objects or results that normally take multiple steps to construct
or are very complex to derive.
The builder interface defines a single method, build(), that classes must implement. The result of this method should be the final configured object or result after all building operations are performed.
It is a recommended practice that the methods supplied to configure the object or result being built return a reference to this so that method calls can be chained together.
Example Builder:
class FontBuilder implements Builder<Font> {
private Font font;
public FontBuilder(String fontName) {
this.font = new Font(fontName, Font.PLAIN, 12);
}
public FontBuilder bold() {
this.font = this.font.deriveFont(Font.BOLD);
return this; // Reference returned so calls can be chained
}
public FontBuilder size(float pointSize) {
this.font = this.font.deriveFont(pointSize);
return this; // Reference returned so calls can be chained
}
// Other Font construction methods
public Font build() {
return this.font;
}
}
Example Builder Usage:
Font bold14ptSansSerifFont = new FontBuilder(Font.SANS_SERIF).bold()
.size(14.0f)
.build();
Type parameters: - <T> – the type of object that the builder will construct or compute.
Since: 3.0
/**
* <p>
* The Builder interface is designed to designate a class as a <em>builder</em>
* object in the Builder design pattern. Builders are capable of creating and
* configuring objects or results that normally take multiple steps to construct
* or are very complex to derive.
* </p>
*
* <p>
* The builder interface defines a single method, {@link #build()}, that
* classes must implement. The result of this method should be the final
* configured object or result after all building operations are performed.
* </p>
*
* <p>
* It is a recommended practice that the methods supplied to configure the
* object or result being built return a reference to {@code this} so that
* method calls can be chained together.
* </p>
*
* <p>
* Example Builder:
* <pre><code>
* class FontBuilder implements Builder<Font> {
* private Font font;
*
* public FontBuilder(String fontName) {
* this.font = new Font(fontName, Font.PLAIN, 12);
* }
*
* public FontBuilder bold() {
* this.font = this.font.deriveFont(Font.BOLD);
* return this; // Reference returned so calls can be chained
* }
*
* public FontBuilder size(float pointSize) {
* this.font = this.font.deriveFont(pointSize);
* return this; // Reference returned so calls can be chained
* }
*
* // Other Font construction methods
*
* public Font build() {
* return this.font;
* }
* }
* </code></pre>
*
* Example Builder Usage:
* <pre><code>
* Font bold14ptSansSerifFont = new FontBuilder(Font.SANS_SERIF).bold()
* .size(14.0f)
* .build();
* </code></pre>
*
*
* @param <T> the type of object that the builder will construct or compute.
*
* @since 3.0
*/
@FunctionalInterface
public interface Builder<T> {
Returns a reference to the object being constructed or result being
calculated by the builder.
Returns: the object constructed or result calculated by the builder.
/**
* Returns a reference to the object being constructed or result being
* calculated by the builder.
*
* @return the object constructed or result calculated by the builder.
*/
T build();
}