Java Web development interview questions
Java Web development interview questions
1. Can we use the constructor, instead of init(), to initialize servlet? - Yes , of course you can use the constructor instead of init(). There’s nothing to stop you. But you shouldn’t. The original reason for init() was that ancient versions of Java couldn’t dynamically invoke constructors with arguments, so there was no way to give the constructur a ServletConfig. That no longer applies, but servlet containers still will only call your no-arg constructor. So you won’t have access to a ServletConfig or ServletContext.
2. How can a servlet refresh automatically if some new data has entered the database? - You can use a client-side Refresh or Server Push.
3. The code in a finally clause will never fail to execute, right? - Using System.exit(1); in try block will not allow finally code to execute.
4. How many messaging models do JMS provide for and what are they? - JMS provide for two messaging models, publish-and-subscribe and point-to-point queuing.
5. What information is needed to create a TCP Socket? - The Local System?s IP Address and Port Number. And the Remote System’s IPAddress and Port Number.
6. What Class.forName will do while loading drivers? - It is used to create an instance of a driver and register it with the DriverManager. When you have loaded a driver, it is available for making a connection with a DBMS.
7. How to Retrieve Warnings? - SQLWarning objects are a subclass of SQLException that deal with database access warnings. Warnings do not stop the execution of an application, as exceptions do; they simply alert the user that something did not happen as planned. A warning can be reported on a Connection object, a Statement object (including PreparedStatement and CallableStatement objects), or a ResultSet object. Each of these classes has a getWarnings method, which you must invoke in order to see the first warning reported on the calling object
8. SQLWarning warning = stmt.getWarnings();
9.
1. Can we use the constructor, instead of init(), to initialize servlet? - Yes , of course you can use the constructor instead of init(). There’s nothing to stop you. But you shouldn’t. The original reason for init() was that ancient versions of Java couldn’t dynamically invoke constructors with arguments, so there was no way to give the constructur a ServletConfig. That no longer applies, but servlet containers still will only call your no-arg constructor. So you won’t have access to a ServletConfig or ServletContext.
2. How can a servlet refresh automatically if some new data has entered the database? - You can use a client-side Refresh or Server Push.
3. The code in a finally clause will never fail to execute, right? - Using System.exit(1); in try block will not allow finally code to execute.
4. How many messaging models do JMS provide for and what are they? - JMS provide for two messaging models, publish-and-subscribe and point-to-point queuing.
5. What information is needed to create a TCP Socket? - The Local System?s IP Address and Port Number. And the Remote System’s IPAddress and Port Number.
6. What Class.forName will do while loading drivers? - It is used to create an instance of a driver and register it with the DriverManager. When you have loaded a driver, it is available for making a connection with a DBMS.
7. How to Retrieve Warnings? - SQLWarning objects are a subclass of SQLException that deal with database access warnings. Warnings do not stop the execution of an application, as exceptions do; they simply alert the user that something did not happen as planned. A warning can be reported on a Connection object, a Statement object (including PreparedStatement and CallableStatement objects), or a ResultSet object. Each of these classes has a getWarnings method, which you must invoke in order to see the first warning reported on the calling object
8. SQLWarning warning = stmt.getWarnings();
9.