==== Error ====
# javac test.java && java test
Exception in thread "main" java.lang.NullPointerException
        at ClassA.func(ClassA.java:15)
        at test.main(test.java:8)



==== test.java ====
     1  import java.io.*;
     2  import java.util.*;
     3
     4  public class test {
     5      public static void main(String[] args) {
     6          System.err.println("========================");
     7          ClassA a = new ClassA();
     8          a.func();
     9      }
    10  }

==== ClassA.java ====
     1  import java.io.*;
     2  import java.util.*;
     3
     4  public class ClassA { // xmlParser
     5      ClassB settings;
     6
     7      public  void ClassA () {
     8          settings = new ClassB();
     9      }
    10
    11      public void func() {
    12          ClassB dummy = new ClassB();
    13          ClassB.ClassBInner temp = dummy.new ClassBInner();
    14
    15          settings.test.add( temp );
    16      }// End Func
    17
    18  }

==== ClassB.java ====
     1  import java.sql.*;
     2  import java.util.*;
     3
     4  public class ClassB { // gimpedSettings
     5      List <ClassBInner> test;
     6
     7      public void ClassB() { // gimpedSettings
     8          test = new LinkedList();
     9      }
    10
    11      public class ClassBInner { // dataSource
    12          String TestString;
    13      }
    14  }