Netbeans and Mysql Connection error

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Java

MySQL

MySQL-Connector

when i try to connect java application with database (Mysql) i have problem to connect with mysql but not showing any error or exceptions .

Code :

try{

Class.forName("com.mysql.jdbc.Driver");
String url ="jdbc:mysql://localhost:3306/clas";
System.out.println("step1 ");
Connection con = DriverManager.getConnection(url,"root", "aaaa");
System.out.println("step2"); 
Statement st=con.createStatement();

}catch(Exception e)
{
System.out.println("Error "+e); 
}

output :
step1

connection is not created ...communication link is correct