public class EmptyAndNull {

    /**

     * @param args

     */

    public static void main(String[] args) {

        // TODO Auto-generated method stub

        String str=new String();

        String str1="";

        String str2=null;

        if(str.isEmpty()){

            System.out.println("str is empty.");

        }

        if(str!=null){

            System.out.println("str is not null");

        }

        if(str1.isEmpty()){

            System.out.println("str1 is empty.");

        }

        if(null!=str1){

            System.out.println("str1 is not null");

        }

    }

}