If you modify your class later—perhaps you add a new field or change a method signature—the JVM will calculate a different ID. When you try to deserialize an old object (saved with the old class version) using the new class version, the IDs won't match. The JVM will throw a java.io.InvalidClassException .
For most projects, using 1L is perfectly fine. If you need a value based on class structure, run serialver manually or install a dedicated extension. Always remember to make the field private static final long . generate serialversionuid in vscode
For example:
If your IDE isn't cooperating, use the JDK's built-in tool in the VS Code terminal: If you modify your class later—perhaps you add
: Hover your mouse over the class name where you see a yellow light bulb or a warning squiggly line indicating the missing serialVersionUID . Trigger Quick Fix : For most projects, using 1L is perfectly fine