Helpful NullPointerExceptions

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In this post we will learn how to use the new feature that show us more details on exceptions

Simple classes below:

  1. Main.java 
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     package dev.artsman.blog;

 class Main {
   public static void main(String[] args) {
     var onewheel = new Onewheel();
     var brand = onewheel.tire().brand();
   }
 }
  2. Onewheel.java: 
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     package dev.artsman.blog;

 class Onewheel {
   private Tire tire;

   Tire tire() {
     return this.tire;
   }
 }
  3. Tire.java: 
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     package dev.artsman.blog;

 class Tire {
   private String brand;

   String brand() {
     return this.brand;
   }
 }

Before JDK 14 the Null Pointer Exception it was like:

Exception in thread “main” java.lang.NullPointerException
at dev.artsman.blog.Main.main(Main.java:7)

With JDK 14, the same exception looks like:

Exception in thread “main” java.lang.NullPointerException: Cannot invoke “dev.artsman.blog.Tire.brand()” because the return value of “dev.artsman.blog.Onewhell.tire()” is null at dev.artsman.blog.Main.main(Main.java:7)

It’s because of the JEP 358: Helpful NullPointerExceptions(https://openjdk.java.net/jeps/358).
This JEP 358 improve the usability of NullPointerExceptions generated by the JVM by describing precisely which variable was null.

Only need add this command line when run -XX:+ShowCodeDetailsInExceptionMessages and enjoy.

xoff.