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Ans. <a href="http://javahungry.blogspot.com/2015/03/difference-between-array-and-arraylist-in-java-example.html" rel="nofollow">http://javahungry.blogspot.com/2015/03/difference-between-array-and-arraylist-in-java-example.html</a>
Ans. A Web service is a service offered by one system to another, for communication over web through http. XML are JSON are usually used for sending across information from one system to another.
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Ans. Load the file in chunks and then process. If we need to do analytic, we can process analytic information for those chunks and then reprocess the processed information from each chunk.
For example - we need to average all marks in the file. We can divide the file and load into 5 chunks and calculate average for each chunk. Then we can collect averages for all 5 chunks and then calculate the final average.
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Ans. In Java JVM memory settings is done by use the arguments -Xms -Xmx. Use M or G after the numbers for indicating Megs and Gigs of bytes respectively. -Xms indicates the minimum and -Xmx the maximum.
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Ans. JDBC is a standard Java Api for Database communication whereas Hibernate is an ORM framework that uses JDBC to connect with Database.
Hibernate is another layer of object table mapping over JDBC that provide a database independent, object oriented and an efficient way of database communication.
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Ans. Yes, we can do that. Compiler wont complain. But using object reference we can only access methods which have been defined for object class i.e clone(), equals(), hashCode(), toString() etc.
We cannot access methods defined in String class or in any class in hierarchy between String and Object.
For example - we cannot do obj.append("abc") as it will now give compile time error.
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Ans. 1. Static class is a class which cannot be instantiated and all its members are static whereas Singleton is the class that only permit creation of single object and then the object is reused.
2. As there is no object in Static class, it cannot participate in runtime Polymorphism.
3. As Static class doesnt allow creating objects and hence it cannot be serialized.
4. Static class body is initialized eagerly at application load time whereas Singleton object can be initiated eagerly using static blocks or lazily on first need.
5. Its not recommended to use pure static class as it fails to use many OOPs concepts.
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Ans. Reliability and Continuity if some of the sites goes down.Easy Scaling up and Down as sites can be added or removed without impacting business continuity.
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This is a very sensitive question and should be dealt with caution. Just simply saying that you never had any disagreement will present you as dumb team member. Showing your self as too aggressive in such decisions will present you as a trouble maker. You should present a situation where you had an argument / disagreement but eventually you and your team mates mutually found a way out of it.
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Ans. It means that the respective folder is not looked upon by Java to look for java or resource files and hence not being included as part of build.It needs to be added to Java Build Path.
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Ans. 1. HashSet doesnt maintain its elements in any specific order and is all random whereas TreeSet maintains elements in natural order 9 order defined by the equals method of TreeSet element type )
2. TreeSet doesnt allow null elements whereas HashMap does.
3. As TreeSet orders elements and is hence insertion is comparatively slower.
4. HashSet performs basic operations like add(), remove(), contains(), size() etc. in a constant size time. A TreeSet performs these operations at the order of log(n) time.
5. HashMap in Java internally backs a HashSet. A NavigableMap backs a TreeSet internally.
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Ans. It make sense if its returning something. It doesnt make sense for void methods where return statement is not preceded by anything. In case of void methods , return as last statement has no impact and is actually a overhead.
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Ans. Spliterator has better performance potential than iterators but only if the potential is used. Spliterator can iterate streams in parallel as well as in sequence whereas iterator can only iterate in sequence.
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Ans. Though there are many differences the way internally they both iterates the collections and streams respectively, but the main difference in performance that is achieved by spliterator as it can iterate Streams in Parallel whereas iterator only iterates collections sequentially.
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Ans. NumberFormatException is the exception that Java throws when we try to convert one data type to the Number data type but the value is not parsable to be a Number.
For example , the following code will result in the NumberFormatException
String string = "Buggy";
int strtoInt = Integer.parseInt(string);
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