60 lines
2.5 KiB
Java
60 lines
2.5 KiB
Java
/**
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* The MIT License
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* Copyright (c) 2014-2016 Ilkka Seppälä
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package com.iluwatar.privateclassdata;
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/**
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*
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* The Private Class Data design pattern seeks to reduce exposure of attributes by limiting their
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* visibility. It reduces the number of class attributes by encapsulating them in single data
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* object. It allows the class designer to remove write privilege of attributes that are intended to
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* be set only during construction, even from methods of the target class.
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* <p>
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* In the example we have normal {@link Stew} class with some ingredients given in constructor. Then
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* we have methods to enumerate the ingredients and to taste the stew. The method for tasting the
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* stew alters the private members of the {@link Stew} class.
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*
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* The problem is solved with the Private Class Data pattern. We introduce {@link ImmutableStew}
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* class that contains {@link StewData}. The private data members of {@link Stew} are now in
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* {@link StewData} and cannot be altered by {@link ImmutableStew} methods.
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*
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*/
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public class App {
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/**
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* Program entry point
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*
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* @param args command line args
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*/
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public static void main(String[] args) {
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// stew is mutable
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Stew stew = new Stew(1, 2, 3, 4);
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stew.mix();
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stew.taste();
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stew.mix();
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// immutable stew protected with Private Class Data pattern
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ImmutableStew immutableStew = new ImmutableStew(2, 4, 3, 6);
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immutableStew.mix();
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}
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}
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