The latest articles on DEV Community by Anushka Kawale (@anushka_kawale_d5f9004b92). https://dev.to/anushka_kawale_d5f9004b92 https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F3464645%2F05c8dee0-39a7-4eef-a62b-07d751f9b74c.png https://dev.to/anushka_kawale_d5f9004b92 en Anushka Kawale Thu, 19 Feb 2026 18:22:10 +0000 https://dev.to/anushka_kawale_d5f9004b92/java-string-immutability-scp-behavior-2ph https://dev.to/anushka_kawale_d5f9004b92/java-string-immutability-scp-behavior-2ph <p>In Java, String is a <strong>non - primitive</strong> data type. <br> String is a sequence of characters / an array of characters.<br> It belongs to the <strong>java.lang</strong> package and represents sequence of characters.<br> </p> <div class="highlight js-code-highlight"> <pre class="highlight plaintext"><code>String name = "Anushka"; </code></pre> </div> <p>String is an object. It is immutable. Stored in special memory called <strong>"String Pool"</strong>. </p> <h2> Why String is Immutable ? </h2> <p>Once created, a String object <strong>cannot be changed</strong>.<br> </p> <div class="highlight js-code-highlight"> <pre class="highlight plaintext"><code>String s = new String("Hello"); s.concat("World"); </code></pre> </div> <p><a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F67jv32hkbgn2lozn0wau.png" class="article-body-image-wrapper"><img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F67jv32hkbgn2lozn0wau.png" alt=" " width="800" height="533"></a><br> What happens internally ? </p> <ul> <li>"Hello" remains unchanged.</li> <li>" World" is checked in SCP (created if not present).</li> <li> A new object "Hello World" is created in heap.</li> </ul> <h2> What is String Constant Pool (SCP) ? </h2> <p>A <strong>String Constant Pool</strong> is a special memory area inside the Heap where Java stores <strong>string literals</strong>.<br> It is used to : </p> <ul> <li>Avoid duplicate objects.</li> <li>Save memory.</li> <li>Improve performance. </li> </ul> <div class="highlight js-code-highlight"> <pre class="highlight plaintext"><code>String s1 = "Java"; String s2 = "Java"; </code></pre> </div> <p>Only <strong>ONE Object</strong> is created in SCP.<br> Both <code>s1</code> and <code>s2</code> point to the same object.<br> </p> <div class="highlight js-code-highlight"> <pre class="highlight plaintext"><code>s1 ─┐ ├──► "Java" (SCP) s2 ─┘ </code></pre> </div> <h2> What If We Use <code>new</code> ? </h2> <div class="highlight js-code-highlight"> <pre class="highlight plaintext"><code>String s3 = new String("Java"); </code></pre> </div> <p><code>Java</code> is stored in SCP. <br> A new Object is created in heap. <br> <code>s3</code> points to heap object.</p> <p>So now two objects exist :</p> <ol> <li>SCP object </li> <li>Heap object</li> </ol> <h2> Why SCP exists ? </h2> <ul> <li>Every string literal would create new object.</li> <li>Huge memory waste.</li> <li>Performance issues. SCP makes Java memory efficient.</li> </ul> java