CORE JAVA Interview Questions-Part13

Question: What is a task's priority and how is it used in scheduling?

Answer: A task's priority is an integer value that identifies the relative order in which it should be executed with respect to other tasks. The scheduler attempts to schedule higher priority tasks before lower priority tasks.

Question: What is the range of the short type?

Answer: The range of the short type is -(2^15) to 2^15 - 1.

Question: What is the purpose of garbage collection?

Answer: The purpose of garbage collection is to identify and discard objects that are no longer needed by a program so that their resources may be reclaimed and reused.

Question: How may messaging models do JMS provide for and what are they?

Answer: JMS provide for two messaging models, publish-and-subscribe and point-to-point queuing

Question: What information is needed to create a TCP Socket? (Networking)

Answer: The Local System?s IP Address and Port Number. And the Remote System's IPAddress and Port Number.

Question: What Class.forName will do while loading drivers? (JDBC)

Answer: 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.

Question: How to Retrieve Warnings? (JDBC)

Answer: 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

E.g.

SQLWarning warning = stmt.getWarnings();

if (warning != null) {

while (warning != null) {

System.out.println("Message: " + warning.getMessage());

System.out.println("SQLState: " + warning.getSQLState());

System.out.print("Vendor error code: ");

System.out.println(warning.getErrorCode());

warning = warning.getNextWarning();

}}