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Ans. Yes, When either we don't want an object to be created ( class having all static elements and hence not required ) or object to be created using a static method or static block.
One such example could be a situation when we would like app to load objects at start up and we would like to restrict new object creation by any request.
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Ans. Item is a sale-able merchandise where as Product is a group of sale-able merchandise which share certain attributes. For example - Cell phone is a product whereas Samsung Galaxy S2 - White is an item.
Quantity is always attached to SKU ( Stock keeping unit ) or items. Product quantity has no relevance in terms of identify the current stock or reorder condition.
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Ans. A dirty read occurs when a transaction is allowed to read data from a row that has been modified by another running transaction but not yet committed.
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Ans. That depends if the interface for the resource in Project B gets changed. If only the internal implementation is changed, No change is required in Project A. Project A is not even required to be rebuilt.
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Ans. This scope indicates that the dependency is not required for normal use of the application, and is only available for the test compilation and execution phases. This scope is not transitive.
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Ans. Step 1 - Upgrade the required dependency , perform build and check build errors
Step 2.1 - If the error is of missing transitive dependency ( which is rare and means that the previous version has a dependency which is missing in the later version ), I would look for the dependency in google and hence will include it as direct dependency in Pom file.
Step 2.2. If the error is for Duplicate dependencies , and the choice is between transitive and direct dependency, I usually remove the direct dependency.
Step 2.3 - If the error is for Duplicate dependencies , and both are transitive dependencies. I first make a choice ( usually later version ) and then ignore the previous version dependency.
Step 2.4 - If the error is for Duplicate dependencies , and there are more than 2 duplicates, I usually ignore it by specifying within maven-enforcer-plugin config.
Step 3 - Perform a Clean Build.
Step 4 - Check Maven Dependency Tree to make sure that Duplicates have been removed or dependency is there in case of missing dependency.
Step 5 - Perform tests and make sure that there are no runtime problems.
Step 6 - If there are runtime problems ( which very likely occurs if you have different version dependencies , very likely by doing 2.4 , you will have to remove step 2.4 and alternately perform 2.2 or 2.3 )
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Ans. Synchronize is used to achieve mutual exclusion i.e at one time, the segment of the code, method that has been declared synchronized should be executed by single thread only and hence the lock needs to be retrieved before executing the segment and then released.
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Ans. ACID stands for Atomicity, Consistency, Isolation, Durability is a set of properties of database transactions.
Atomicity means all or nothing. i.e parts of a transaction shouldn't commit if any one of them fails. Either the whole transaction should succeed or it should be complete rollback.
Consistency means that any transaction should lead database from one stabe state to another.
Isolation means that the execution of transaction results in a system state that would be obtained if transactions were executed serially.
Durability means that when a transaction is committed it forms the permanent state of database.
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Ans. The prototype pattern is a creational design pattern. It is used when the type of objects to create is determined by a prototypical instance, which is cloned to produce new objects. Prototype is used when we need duplicate copies of objects.
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Ans. A finally block of code always executes, whether or not an exception has occurred.The only time finally won't be called is if you call System.exit() or if the JVM crashes first.
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Ans. But Collections.emptyList() returns an Immutable list whereas new arraylist() creates a mutable list.
Advantage of getting an empty list using Collections.emptyList is that it returns a singleton list which can be shared among many references and hence made immutable. This is good fit for situations where we would like to initialize a list to basic minimum empty to avoid null pointer exception.
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Q1917. There is a Table Student having Student Id, Name and Total Marks. Can you please write an SQL that will display the maximum marks obtained by a student ?
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