core java in java questions asked in companies

When JVM compiles the class file he does not compile the full class file in one shot. Compilation is done on function basis or file basis. Advantage gained from this is that heavy parsing of original source code is avoided. Depending on need basis the compilation is done. This typ of compilation is termed as … Read more

JVM stands for Java Virtual Machine. It’s an abstract computer or virtual computer which runs the compiled java programs. Actually JVM is a software implementation which stands on the top of the real hardware platform and operating system. It provides abstraction between the compiled java program and the hardware and operating system. So the compiled … Read more

java.util.Comparator java.util.Comparator compares some other class’s instances. java.lang.Comparable java.lang.Comparable compares another object with itself. Differentiate between final, finally and finalize. The keyword is final. It is used for declaring a constant It prevents a class from producing subclasses. finally is a code.It always executes when the try block is finished, Unless System.exit() has been called.finalize() is a … Read more

Remote method invocation is called RMI. One can work with remote object using RMI. It gives a impression that you are working with a object that resides within your own JVM though it is somewhere. The protocol used by RMI is RMI-IIOP Define a Collection API. The set of classes and interfaces supporting the operation … Read more

Unicode requires 16 bits ASCII require 7 bits. but it is usually represented as 8 bits. UTF-8 represents characters using 8, 16, and 18 bit patterns. UTF-16 uses 16-bit and larger bit patterns. Define reflection Reflection allows program related access to information about the fields, methods and constructors of loaded classes It use reflected fields, … Read more