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Ans. The Spring container is able to autowire relationships between collaborating beans. This means that it is possible to automatically let Spring resolve collaborators (other beans) for your bean by inspecting the contents of the BeanFactory without using and elements.
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Ans. MVC is a Design Pattern that facilititates loose coupling by segregating responsibilities in a Web application
1. Controller receives the requests and handles overall control of the request
2. Model holds majority of the Business logic, and
3. View comprise of the view objects and GUI component
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Ans. Collections are re-sizable in nature. We can increase or decrease the size as per recruitment.
Collections can hold both homogeneous and heterogeneous data's.
Every collection follows some standard data structures.
Collection provides many useful built in methods for traversing,sorting and search.
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Ans. String is immutable in java and stored in String pool. Once it's created it stays in the pool until unless garbage collected, so even though we are done with password it's available in memory for longer duration and there is no way to avoid it. It's a security risk because anyone having access to memory dump can find the password as clear text.
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Ans. Since String is immutable, its hashcode is cached at the time of creation and it doesnt need to be calculated again. This makes it a great candidate for key in a Map and its processing is fast than other HashMap key objects. This is why String is mostly used Object as HashMap keys.
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Ans. REST or Representational State Transfer is a flexible architecture style for creating web services that recommends the following guidelines -
1. http for client server communication,
2. XML / JSON as formatiing language ,
3. Simple URI as address for the services and,
4. stateless communication.
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Very Frequently asked. Favorite question in walkins and telephonic interviews. Usually among first few questions. Asked in different variants. Must know for intermediate and expert professionals.Among Top 10 frequently asked questions.
Q144. What is rule regarding overriding equals and hashCode method ?
Ans. It means that the type of variables are checked at compile time in Java.The main advantage here is that all kinds of checking can be done by the compiler and hence will reduce bugs.
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Ans. 1. First level cache is enabled by default whereas Second level cache needs to be enabled explicitly.
2. First level Cache came with Hibernate 1.0 whereas Second level cache came with Hibernate 3.0.
3. First level Cache is Session specific whereas Second level cache is shared by sessions that is why First level cache is considered local and second level cache is considered global.
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Ans. HBM Files ( Mapping )
DB Connection ( DB Connection String , User Name , Password , Pool Size )
SQL Dialect ( SQL variant to be generated )
Show SQL ( Show / No show SQL on Console )
Auto Commit ( True / False )
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Ans. If id doesnt exist in the DB load throws an exception whereas get returns null in that case.get makes the call to DB immediately whereas load makes the call to proxy.
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Ans. Underlying data structure for ArrayList is Array whereas LinkedList is the linked list and hence have following differences -
1. ArrayList needs continuous memory locations and hence need to be moved to a bigger space if new elements are to be added to a filled array which is not required for LinkedList.
2. Removal and Insertion at specific place in ArrayList requires moving all elements and hence leads to O(n) insertions and removal whereas its constant O(1) for LinkedList.
3. Random access using index in ArrayList is faster than LinkedList which requires traversing the complete list through references.
4. Though Linear Search takes Similar Time for both, Binary Search using LinkedList requires creating new Model called Binary Search Tree which is slower but offers constant time insertion and deletion.
5. For a set of integers you want to sort using quicksort, it's probably faster to use an array; for a set of large structures you want to sort using selection sort, a linked list will be faster.
Ans. It's a feature to lazily initialize dependencies , relationship and associations from the Database. Any related references marked as @OneToMany or @ManyToMany are loaded lazily i.e when they are accessed and not when the parent is loaded.
Which Java version introduced Lambda expressions ?
Java 5
Java 7
Java 8
Java 9
Very frequently asked. Usually followed by questions related to private constructor and synchronized access. Frequently asked in JPMorgan and TCS (Based on 2 feedback)
Ans. throw is used to re throw an exception.throws is used to declare that the method throws the respective exceptions.try block is used to identify if the respective block has thrown any exception.catch is used to catch the exception that has been thrown by the respective try block.
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Ans. Composition - has-a relationship between objects.
Inheritance - is-a relationship between classes.
Composition - Composing object holds a reference to composed objects and hence relationship is loosely bound.
Inheritance - Derived object carries the base class definition in itself and hence its tightly bound.
Composition - Used in Dependency Injection
Inheritance - Used in Runtime Polymorphism
Composition - Single class objects can be composed within multiple classes.
Inheritance - Single class can only inherit 1 Class.
Composition - Its the relationship between objects.
Inheritance - Its the relationship between classes.
Ans. We are using Agile methodology. I attend daily stand up where the development leads takes the status of assigned stories, achievements, any bottlenecks or challenges. We follow iteration of 2 weeks.
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