The gist that shows an example of an NPE in the Java programming language.

gist_java_and_npe.java

public class Main {
    public static void main(String[] args) {
        User user = null;
        System.out.println(user.name); // Exception in thread "main" java.lang.NullPointerException at Main.main(Main.java:3)
    }
}

class User {
    String name;
}