Java Tech Workshop

Sep 9, 2026 · Fundamentals

Why Your Custom java.lang.String Can Never Replace the JDK's String

This article explains why a custom java.lang.String class cannot replace the JDK's String, detailing the parent delegation class loading model, Bootstrap ClassLoader's role, core class protection mechanisms, Java 9+ module system restrictions, and why attempts to bypass these (custom class loaders, -Xbootclasspath, --patch-module, Java Agents) fail or are unsafe.