1"use strict";(self.webpackChunkjava_design_patterns_vuepress_web=self.webpackChunkjava_design_patterns_vuepress_web||[]).push([[18220],{55615(s,i){i.A=(s,i)=>{const a=s.__vccOpts||s;for(const[s,n]of i)a[s]=n;return a}},73448(s,i,a){a.r(i),a.d(i,{comp:()=>h,data:()=>p});var n=a(19195);const t=a.p+"assets/img/private-class-data-mind-map.18d3218f.png",e=a.p+"assets/img/private-class-data-flowchart.f39b021f.png",l={},h=(0,a(55615).A)(l,[["render",function(s,i){return(0,n.uX)(),(0,n.CE)("div",null,[...i[0]||(i[0]=[(0,n.Fv)('<h2 id="also-known-as" tabindex="-1"><a class="header-anchor" href="#also-known-as"><span>Also known as</span></a></h2><ul><li>Data Hiding</li><li>Encapsulation</li></ul><h2 id="intent-of-private-class-data-design-pattern" tabindex="-1"><a class="header-anchor" href="#intent-of-private-class-data-design-pattern"><span>Intent of Private Class Data Design Pattern</span></a></h2><p>The Private Class Data design pattern in Java focuses on restricting access to the internal state of an object, enhancing security and reducing risks of data corruption through controlled method access.</p><h2 id="detailed-explanation-of-private-class-data-pattern-with-real-world-examples" tabindex="-1"><a class="header-anchor" href="#detailed-explanation-of-private-class-data-pattern-with-real-world-examples"><span>Detailed Explanation of Private Class Data Pattern with Real-World Examples</span></a></h2><p>Real-world example</p><blockquote><p>A real-world analogy for the Private Class Data pattern is the way a bank protects customer account information. Just like a class with private fields, a bank keeps sensitive data such as account balances, transaction history, and personal information private and only accessible through specific methods. Customers interact with their accounts through well-defined interfaces such as ATMs or online banking portals, which enforce security and validation rules, ensuring that unauthorized access or modifications are prevented. This controlled access mechanism ensures the integrity and security of the data, similar to how Private Class Data protects and manages access to class attributes in software design.</p></blockquote><p>In plain words</p><blockquote><p>Private class data pattern prevents manipulation of data that is meant to be immutable by separating the data from the methods that use it into a class that maintains the data state.</p></blockquote><p>Wikipedia says</p><blockquote><p>Private class data is a design pattern in computer programming used to encapsulate class attributes and their manipulation.</p></blockquote><p>Mind map</p><p><img src="'+t+'" alt="Private Class Data mind map"></p><p>Flowchart</p><p><img src="'+e+'" alt="Private Class Data flowchart"></p><h2 id="programmatic-example-of-private-class-data-pattern-in-java" tabindex="-1"><a class="header-anchor" href="#programmatic-example-of-private-class-data-pattern-in-java"><span>Programmatic Example of Private Class Data Pattern in Java</span></a></h2><p>Imagine you are cooking a stew for your family dinner. You want to stop your family members from tasting the stew while you're still preparing it. If they do, there might not be enough stew left for dinner.</p><p>First, we have a <code>Stew</code> class where its data is not protected by private class data, making the stew's ingredient mutable to class methods.</p><div class="language-java line-numbers-mode" data-highlighter="shiki" data-ext="java" style="--shiki-light:#383A42;--shiki-dark:#abb2bf;--shiki-light-bg:#FAFAFA;--shiki-dark-bg:#282c34;"><pre class="shiki shiki-themes one-light one-dark-pro vp-code"><code class="language-java"><span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">@</span><span style="--shiki-light:#A626A4;--shiki-dark:#E5C07B;">Slf4j</span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;">public</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> class</span><span style="--shiki-light:#C18401;--shiki-dark:#E5C07B;"> Stew</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> {</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;"> </span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> private</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> int</span><span style="--shiki-light:#E45649;--shiki-dark:#E06C75;"> numPotatoes</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">;</span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> private</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> int</span><span style="--shiki-light:#E45649;--shiki-dark:#E06C75;"> numCarrots</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">;</span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> private</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> int</span><span style="--shiki-light:#E45649;--shiki-dark:#E06C75;"> numMeat</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">;</span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> private</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> int</span><span style="--shiki-light:#E45649;--shiki-dark:#E06C75;"> numPeppers</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">;</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;"> </span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> public</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;"> Stew</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">(</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;">int</span><span style="--shiki-light:#383A42;--shiki-light-font-style:inherit;--shiki-dark:#E06C75;--shiki-dark-font-style:italic;"> numPotatoes</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">, </span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;">int</span><span style="--shiki-light:#383A42;--shiki-light-font-style:inherit;--shiki-dark:#E06C75;--shiki-dark-font-style:italic;"> numCarrots</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">, </span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;">int</span><span style="--shiki-light:#383A42;--shiki-light-font-style:inherit;--shiki-dark:#E06C75;--shiki-dark-font-style:italic;"> numMeat</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">, </span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;">int</span><span style="--shiki-light:#383A42;--shiki-light-font-style:inherit;--shiki-dark:#E06C75;--shiki-dark-font-style:italic;"> numPeppers</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">)</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> {</span></span>\n<span class="line"><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;"> this</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;">numPotatoes</span><span style="--shiki-light:#383A42;--shiki-dark:#56B6C2;"> =</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> numPotatoes;
1</span></span>\n<span class="line"><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;"> this</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;">numCarrots</span><span style="--shiki-light:#383A42;--shiki-dark:#56B6C2;"> =</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> numCarrots;</span></span>\n<span class="line"><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;"> this</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;">numMeat</span><span style="--shiki-light:#383A42;--shiki-dark:#56B6C2;"> =</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> numMeat;</span></span>\n<span class="line"><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;"> this</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;">numPeppers</span><span style="--shiki-light:#383A42;--shiki-dark:#56B6C2;"> =</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> numPeppers;</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> }</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;"> </span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> public</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> void</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;"> mix</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">()</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> {</span></span>\n<span class="line"><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;"> LOGGER</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;">info</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">(</span><span style="--shiki-light:#50A14F;--shiki-dark:#98C379;">"Mixing the stew we find: {} potatoes, {} carrots, {} meat and {} peppers"</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">,</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> numPotatoes, numCarrots, numMeat, numPeppers);</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> }</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;"> </span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> public</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> void</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;"> taste</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">()</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> {</span></span>\n<span class="line"><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;"> LOGGER</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;">info</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">(</span><span style="--shiki-light:#50A14F;--shiki-dark:#98C379;">"Tasting the stew"</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">);</span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> if</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> (numPotatoes </span><span style="--shiki-light:#383A42;--shiki-dark:#56B6C2;">></span><span style="--shiki-light:#986801;--shiki-dark:#D19A66;"> 0</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">) {</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> numPotatoes--;</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> }</span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> if</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> (numCarrots </span><span style="--shiki-light:#383A42;--shiki-dark:#56B6C2;">></span><span style="--shiki-light:#986801;--shiki-dark:#D19A66;"> 0</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">) {</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> numCarrots--;</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> }</span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> if</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> (numMeat </span><span style="--shiki-light:#383A42;--shiki-dark:#56B6C2;">></span><span style="--shiki-light:#986801;--shiki-dark:#D19A66;"> 0</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">) {</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> numMeat--;</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> }</span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> if</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> (numPeppers </span><span style="--shiki-light:#383A42;--shiki-dark:#56B6C2;">></span><span style="--shiki-light:#986801;--shiki-dark:#D19A66;"> 0</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">) {</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> numPeppers--;</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> }</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> }</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">}</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>Now, we have <code>ImmutableStew</code> class, where its data is protected by <code>StewData</code> record. The methods in <code>ImmutableStew</code> are unable to manipulate the data of the <code>StewData</code> class.</p><div class="language-java line-numbers-mode" data-highlighter="shiki" data-ext="java" style="--shiki-light:#383A42;--shiki-dark:#abb2bf;--shiki-light-bg:#FAFAFA;--shiki-dark-bg:#282c34;"><pre class="shiki shiki-themes one-light one-dark-pro vp-code"><code class="language-java"><span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;">public</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> record</span><span style="--shiki-light:#C18401;--shiki-dark:#E5C07B;"> StewData</span><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;">(</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;">int</span><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;"> numPotatoes</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">,</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> int</span><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;"> numCarrots</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">,</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> int</span><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;"> numMeat</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">,</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> int</span><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;">
1 numPeppers) </span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">{}</span></span>\n<span class="line"></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">@</span><span style="--shiki-light:#A626A4;--shiki-dark:#E5C07B;">Slf4j</span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;">public</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> class</span><span style="--shiki-light:#C18401;--shiki-dark:#E5C07B;"> ImmutableStew</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> {</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;"> </span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> private</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> final</span><span style="--shiki-light:#C18401;--shiki-dark:#E5C07B;"> StewData</span><span style="--shiki-light:#E45649;--shiki-dark:#E06C75;"> data</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">;</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;"> </span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> public</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;"> ImmutableStew</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">(</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;">int</span><span style="--shiki-light:#383A42;--shiki-light-font-style:inherit;--shiki-dark:#E06C75;--shiki-dark-font-style:italic;"> numPotatoes</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">, </span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;">int</span><span style="--shiki-light:#383A42;--shiki-light-font-style:inherit;--shiki-dark:#E06C75;--shiki-dark-font-style:italic;"> numCarrots</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">, </span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;">int</span><span style="--shiki-light:#383A42;--shiki-light-font-style:inherit;--shiki-dark:#E06C75;--shiki-dark-font-style:italic;"> numMeat</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">, </span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;">int</span><span style="--shiki-light:#383A42;--shiki-light-font-style:inherit;--shiki-dark:#E06C75;--shiki-dark-font-style:italic;"> numPeppers</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">)</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> {</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> data </span><span style="--shiki-light:#383A42;--shiki-dark:#56B6C2;">=</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> new</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;"> StewData</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">(numPotatoes, numCarrots, numMeat, numPeppers);</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> }</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;"> </span></span>\n<span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> public</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> void</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;"> mix</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">()</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> {</span></span>\n<span class="line"><span style="--shiki-light:#C18401;--shiki-dark:#E5C07B;"> LOGGER</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> .</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;">info</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">(</span><span style="--shiki-light:#50A14F;--shiki-dark:#98C379;">"Mixing the immutable stew we find: {} potatoes, {} carrots, {} meat and {} peppers"</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">,</span></span>\n<span class="line"><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;"> data</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;">getNumPotatoes</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">(), </span><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;">data</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;">getNumCarrots</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">(), </span><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;">data</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;">getNumMeat</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">(), </span><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;">data</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;">getNumPeppers</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">());</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;"> }</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">}</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>Let's try creating an instance of each class and call their methods:</p><div class="language-java line-numbers-mode" data-highlighter="shiki" data-ext="java" style="--shiki-light:#383A42;--shiki-dark:#abb2bf;--shiki-light-bg:#FAFAFA;--shiki-dark-bg:#282c34;"><pre class="shiki shiki-themes one-light one-dark-pro vp-code"><code class="language-java"><span class="line"><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;">public</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> static</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> void</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;"> main</span><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;">(</span><span style="--shiki-light:#C18401;--shiki-dark:#E5C07B;">String</span><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;">[] args) {</span></span>\n<span class="line"><span style="--shiki-light:#A0A1A7;--shiki-light-font-style:italic;--shiki-dark:#7F848E;--shiki-dark-font-style:italic;"> // stew is mutable</span></span>\n<span class="line"><span style="--shiki-light:#C18401;--shiki-dark:#C678DD;"> var</span><span style="--shiki-light:#E45649;--shiki-dark:#E06C75;"> stew </span><span style="--shiki-light:#383A42;--shiki-dark:#56B6C2;">=</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> new</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;"> Stew</span><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;">(</span><span style="--shiki-light:#986801;--shiki-dark:#D19A66;">1</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">,</span><span style="--shiki-light:#986801;--shiki-dark:#D19A66;"> 2</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">,</span><span style="--shiki-light:#986801;--shiki-dark:#D19A66;"> 3</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">,</span><span style="--shiki-light:#986801;--shiki-dark:#D19A66;"> 4</span><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;">)</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">;</span></span>\n<span class="line"><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;"> stew</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;">mix</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">();</span></span>\n<span class="line"><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;"> stew</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;">taste</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">();</span></span>\n<span class="line"><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;"> stew</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;">mix</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">();</span></span>\n<span class="line"></span>\n<span class="line"><span style="--shiki-light:#A0A1A7;--shiki-light-font-style:italic;--shiki-dark:#7F848E;--shiki-dark-font-style:italic;"> // immutable stew protected with Private Class Data pattern</span></span>\n<span class="line"><span style="--shiki-light:#C18401;--shiki-dark:#C678DD;"> var</span><span style="--shiki-light:#E45649;--shiki-dark:#E06C75;"> immutableStew </span><span style="--shiki-light:#383A42;--shiki-dark:#56B6C2;">=</span><span style="--shiki-light:#A626A4;--shiki-dark:#C678DD;"> new</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;"> ImmutableStew</span><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;">(</span><span style="--shiki-light:#986801;--shiki-dark:#D19A66;">2</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">,</span><span style="--shiki-light:#986801;--shiki-dark:#D19A66;"> 4</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">,</span><span style="--shiki-light:#986801;--shiki-dark:#D19A66;"> 3</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">,</span><span style="--shiki-light:#986801;--shiki-dark:#D19A66;"> 6</span><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;">)</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">;</span></span>\n<span class="line"><span style="--shiki-light:#E45649;--shiki-dark:#E5C07B;"> immutableStew</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">.</span><span style="--shiki-light:#4078F2;--shiki-dark:#61AFEF;">mix</span><span style="--shiki-light:#383A42;--shiki-dark:#ABB2BF;">();</span></span>\n<span class="line"><span style="--shiki-light:#383A42;--shiki-dark:#E06C75;">}</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>Program output:</p><div class="language- line-numbers-mode" data-highlighter="shiki" data-ext="" style="--shiki-light:#383A42;--shiki-dark:#abb2bf;--shiki-light-bg:#FAFAFA;--shiki-dark-bg:#282c34;"><pre class="shiki shiki-themes one-light one-dark-pro vp-code"><code class="language-"><span class="line"><span>08:00:08.210 [main] INFO com.iluwatar.privateclassdata.Stew -- Mixing the stew we find: 1 potatoes, 2 carrots, 3 meat and 4 peppers</span></span>\n<span class="line"><span>08:00:08.212 [main] INFO com.iluwatar.privateclassdata.Stew -- Tasting the stew</span></span>\n<span class="line"><span>08:00:08.212 [main] INFO com.iluwatar.privateclassdata.Stew -- Mixing the stew we find: 0 potatoes, 1 carrots, 2 meat and 3 peppers</span></span>\n<span class="line"><span>08:00:08.213 [main] INFO com.iluwatar.privateclassdata.ImmutableStew -- Mixing the immutable stew we find: 2 potatoes, 4 carrots, 3 meat and 6 peppers</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="when-to-use-the-private-class-data-pattern-in-java" tabindex="-1"><a class="header-anchor" href="#when-to-use-the-private-class-data-pattern-in-java"><span>When to Use the Private Class Data Pattern in Java</span></a></h2><p>Use the Private Class Data pattern when</p><ul><li>When you want to protect the integrity of an objectâs state.</li><li>When you need to limit the visibility of the internal data of an object to prevent unintended modification.</li><li>In scenarios where multiple classes need to share access to some common data without exposing it directly.</li></ul><h2 id="real-world-applications-of-private-class-data-pattern-in-java" tabindex="-1"><a class="header-anchor" href="#real-world-applications-of-private-class-data-pattern-in-java"><span>Real-World Applications of Private Class Data Pattern in Java</span></a></h2><ul><li>Java Beans, where properties are accessed via getters and setters.</li><li>In many Java libraries where the internal state is hidden from the user to ensure consistency and security.</li><li>Enterprise applications where sensitive data needs to be protected from direct access.</li></ul>
1<h2 id="benefits-and-trade-offs-of-private-class-data-pattern" tabindex="-1"><a class="header-anchor" href="#benefits-and-trade-offs-of-private-class-data-pattern"><span>Benefits and Trade-offs of Private Class Data Pattern</span></a></h2><p>Benefits:</p><ul><li>Enhanced Security: Reduces the risk of unintended data corruption by encapsulating the data.</li><li>Ease of Maintenance: Changes to the internal representation of data do not affect external code.</li><li>Improved Abstraction: Users interact with a simplified interface without worrying about the complexities of data management.</li></ul><p>Trade-offs:</p><ul><li>Performance Overhead: Additional method calls (getters/setters) can introduce slight performance overhead.</li><li>Complexity: May increase the complexity of the class design due to the additional layer of methods for data access.</li></ul><h2 id="related-java-design-patterns" tabindex="-1"><a class="header-anchor" href="#related-java-design-patterns"><span>Related Java Design Patterns</span></a></h2><ul><li><a href="https://java-design-patterns.com/patterns/proxy/" target="_blank" rel="noopener noreferrer">Proxy</a>: Both patterns restrict access to the underlying object but Proxy controls access to the object itself, while Private Class Data controls access to the data.</li><li><a href="https://java-design-patterns.com/patterns/singleton/" target="_blank" rel="noopener noreferrer">Singleton</a>: Ensures that a class has only one instance and provides a global point of access to it; often used to manage shared data with controlled access.</li><li><a href="https://java-design-patterns.com/patterns/decorator/" target="_blank" rel="noopener noreferrer">Decorator</a>: Adds behavior to an object without altering its structure; can be combined with Private Class Data to manage additional state privately.</li></ul><h2 id="references-and-credits" tabindex="-1"><a class="header-anchor" href="#references-and-credits"><span>References and Credits</span></a></h2><ul><li><a href="https://amzn.to/3UJTZJk" target="_blank" rel="noopener noreferrer">Clean Code: A Handbook of Agile Software Craftsmanship</a></li><li><a href="https://amzn.to/3w0pvKI" target="_blank" rel="noopener noreferrer">Design Patterns: Elements of Reusable Object-Oriented Software</a></li><li><a href="https://amzn.to/4cGk2Jz" target="_blank" rel="noopener noreferrer">Effective Java</a></li></ul>',39)])])}]]),p=JSON.parse('{"path":"/patterns/private-class-data/","title":"Private Class Data Pattern in Java: Safeguarding Data Integrity with Encapsulation","lang":"en-US","frontmatter":{"title":"Private Class Data Pattern in Java: Safeguarding Data Integrity with Encapsulation","shortTitle":"Private Class Data","description":"Explore the Private Class Data pattern in Java, ideal for enhancing data security and integrity in object-oriented programming. Learn how it prevents unintended data manipulation with encapsulation.","category":"Structural","language":"en","tag":["Abstraction","Encapsulation","Security"],"head":[["script",{"type":"application/ld+json"},"{\\"@context\\":\\"https://schema.org\\",\\"@type\\":\\"Article\\",\\"headline\\":\\"Private Class Data Pattern in Java: Safeguarding Data Integrity with Encapsulation\\",\\"image\\":[\\"\\"],\\"dateModified\\":null,\\"author\\":[{\\"@type\\":\\"Person\\",\\"name\\":\\"iluwatar\\",\\"url\\":\\"https://github.com/iluwatar/java-design-patterns-vuepress-web\\"}]}"],["meta",{"property":"og:url","content":"https://java-design-patterns.com/patterns/private-class-data/"}],["meta",{"property":"og:site_name","content":"Java Design Patterns"}],["meta",{"property":"og:title","content":"Private Class Data Pattern in Java: Safeguarding Data Integrity with Encapsulation"}],["meta",{"property":"og:description","content":"Explore the Private Class Data pattern in Java, ideal for enhancing data security and integrity in object-oriented programming. Learn how it prevents unintended data manipulation with encapsulation."}],["meta",{"property":"og:type","content":"article"}],["meta",{"property":"og:locale","content":"en-US"}],["meta",{"property":"og:locale:alternate","content":"zh-CN"}
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