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Ans. Builds can be triggered by source code management commits. Can be triggered after completion of other builds. Can be scheduled to run at specified time ( crons ) Manual Build Requests
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Ans. Nagios is open source system , network and infrastructure monitoring software application. It alerts the user if anything goes wrong. Nagios is widely used as monitoring tool for enterprise applications.
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LikeDiscussCorrect / Improve  production support   application support   nagios   system monitoring
Q2434. Should we have instance variables in the Spring Bean which has been scoped as Singleton ?
Ans. No, if required we should only have final variables.Bean scoped singleton means that only one instance of the bean will be created and will be shared among different requests and hence instance variables will get shared too.
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Ans. JIRA is written in Java and uses the Pico IOC container,Apache OFBiz entity engine, and WebWork technology stack. For remote procedure calls (RPC), JIRA supports REST, SOAP, and XML RPC.
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Ans. Stateless objects are the objects without instance fields (instance variables). The class may have compile time constants i.e static final fields.Immutable objects are the objects which have state but the state cannot be changed after initialization. Both are Thread safe.
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Ans. Abstract classes can have both abstract methods ( method declarations ) as well as concrete methods ( inherited to the derived classes ) whereas Interfaces can only have abstract methods ( method declarations ).
A class can extend single abstract class whereas it can implement multiple interfaces.
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Though the following code will compile fine but will result in ClassCastException during runtime.
Fruit fruit = new Apple();
Banana banana = Banana(fruit); // ClassCastException
This code will not give compile time error as Banana and Fruit are related as Banana either extends or implement Fruit, So downcasting is acceptable. With this code we assume that the Fruit handler will have the Apple object at that point, violating which the code will throw the exception.
This exception can be avoided by following code.
Fruit fruit = new Apple();
if(fruit instanceOf Banana){
Banana banana = Banana(fruit); // ClassCastException
}
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Ans. DocLint Provide a means to detect errors in Javadoc comments early in the development cycle and in a way that is easily linked back to the source code.
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Ans. Spring caching makes use of its intercepting capabilities to add caching to method calls. Therefore, the entire object is cached and reused. Hibernate, on the other hand, has more domain-specific knowledge of the Entity being cached and can handle the objects more appropriately.
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Ans. It's a choice to be made whether to use first approach ( Thread class ) or second approach ( runnable interface ) by the programmer. The second facility has been given for cases where your class is already extending some parent class and hence cannot extend another class ( for Thread ) as Java doesn't allow multiple inheritance.
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Ans. Thread class holds the definition of start method ( This is the method that starts execution of new thread and then calls run method within the scope of new thread ). Interfaces don't hold any definition and so does runnable. So it makes it necessary the usage of Thread class , whatever implementation you choose.
When your class extends the thread class, it carries the definition of start method from parent Thread class onto itself and hence new yourClass.start() helps starting a new thread and then executing run method in that new thread scope.
When you implement runnable interface , you are just making it sure to the JVM that you have implemented the required method ( run() ) which the Thread start method will look for upon executing start method.
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Ans. Http is connection less by default. header informs hosts to keep the connection alive so that the same connection can be reused for multiple communication.
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