Here’s an example of how to create an exception. You can extend this example as needed for your own applications. The important principle is the exeption’s mechanism, not its subject:

class PrivateException extends Exception{//constructor without parameterspublic PrivateException() {}//constructor for exception descriptionpublic PrivateException(String description)    {    super(description);    }}class Test     {     public Test(){}          //this method will throw a PrivateException     void method1(int a ,int b) throws PrivateException      {      System.out.println("You called method1 !!!

");      //specify when  to generate the exception      if(a==b)        {        String description="In method "method1" a PrivateException         has been generated
 "+         " The "+a+" and "+b+" arguments are equal!!!
"+         " Call this method with no equal arguments.";        throw new PrivateException(description);        }      }                  //this method will throw a PrivateException      void method2(int a, int b)throws PrivateException       {       System.out.println("You called method2 !!!

");       //specify when to generate the exception       if((a*b)>10)          {         String description="In method "method2" a PrivateException          has been generated
 "+         " The "+a+" * "+b+" is grater that 10 !!!
"+         " Call this method with smaller arguments.";         throw new PrivateException(description);         }       }            }public class TestPrivateException{ public static void main(String[] args)  {  Test t=new Test();  try{     t.method1(22,20); //NO EXCEPTION      t.method2(11,23); //EXCEPTION        }catch(PrivateException e)       {e.printStackTrace();}  }}