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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. Before Unicode there were many language / country standards like ASCII , ISO , KOI and BIG 5. In order to accommodate multiple language letters and to overcome problems with using different multiple standards , a new language standard was developed i.e unicode system.
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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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As we haven't specified the type of TreeSet, it being evaluated with the first element insertion. Once it's identified that it's of type String and as no comparator has been defined, the comparison is done using the String compareTo method. String compareTo method compares the elements by the content / value.
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Ans. float is a native data type whereas Float is a class. A Float object will always take more memory than float variable as there are metadata overheads with the objects.
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Q717. Difference between HashMap and WeakHashMap ?
Ans. WeakHashMap uses weak reference for keys, which means if the key object doesn't have any reference then both key/value mapping will become eligible for garbage collection.
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Q720. When are static and instance methods resolved ? During compile time or Runtime ?
Ans. Static methods are resolved during compile time and hence they cannot participate in runtime polymorphism. Instance methods are resolved during runtime.
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Q726. Have you used Kafka in your project ? If Yes, for what ?
Ans. We were using Kafka as a replacement for JMS Message Queue for better throughput. We were just using a simple Java multi threaded client as order of message consumption didn't matter to us.
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Q730. Which is of the following is NOT TRUE for JVM ?
a. JVM reads Byte Code and generates Machine Code. b. JVM is a virtual Machine that acts as a intermediary between Java Application and Host Operating System. c. JVM reads Source Code and generates Byte Code. d. JVM acts as a translator that translates different Machine code ( on the basis of Host Machine ) for a common Byte Code.
Ans. JVM reads Source Code and generates Byte Code.
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Which of the following can throw ClassCastException ?
