Computer Language (JAVA)

In Java, every class directly or indirectly extends the Object class. Object is the root of the class hierarchy. System, String, and Integer are all classes that themselves extend Object.

Java technology is a comprehensive platform that includes a programming language, development environment (tools like JDK), application environment (JRE), and deployment environment. Therefore option C (both 1 and 2) is correct.

Static blocks are executed when the class is loaded, even before the main method is called. This is because static initialization happens during class loading, which occurs before any method (including main) can be executed.

JNI (Java Native Interface) allows Java code to call and be called by native applications and libraries written in other languages like C, C++, or assembly. It provides a bridge between Java and native code execution through the operating system.

The default value for char primitive type in Java is '\u0000' (the null character). This is Unicode value 0. Option B (0) is an int, C (null) is only for reference types, and D (0.0f) is for float.

The code is valid Java syntax. It defines a class with a main method that prints 'Helloworld'. There are no compilation or runtime errors. The program will successfully execute and output the string.

This code demonstrates array type covariance and casting. An int array can be assigned to an Object reference, then cast back to int array. The for-each loop prints 012345. No errors occur.

JIT stands for Just In Time Compiler. It compiles bytecode to native machine code at runtime to improve performance. Options A, C, and D are incorrect expansions.

In Java, the int primitive type is consistently 32 bits (4 bytes) across all platforms, ensuring portability. The options present different bit sizes, with 32-bit being the standard Java int size. Other languages like C/C++ may have variable int sizes depending on the platform, but Java specifies this precisely.

Constructors are NOT inherited in Java - each class must define its own constructors. A child class can CALL the parent constructor using super(), but it does not inherit it. The child class must have its own constructor, even if it only calls super().

The Scanner class is in java.util package, which is imported with import java.util.*. Option A incorrectly imports java.lang (auto-imported), Option B imports java.io for I/O operations, and Option D imports java.awt for GUI components. Scanner is specifically a utility class for text parsing.

In Java AWT, the default layout manager for a Frame is BorderLayout (5 regions: North, South, East, West, Center). FlowLayout arranges components left-to-right, GridLayout divides into equal grid cells, and CardLayout shows one component at a time. BorderLayout is the Frame's default.

For formatted output of strings, %s is the correct format specifier. %c is for characters, %d for decimal integers, and %f for floating-point numbers. printf() and String.format() use these specifiers - %s specifically handles string output.

To invoke a parent class constructor from a child class constructor, use super() as the first statement. Option A (employee.super()) and C (manager.super()) are invalid syntax. The super() keyword alone calls the parent constructor - it's a language keyword, not a method on any object.

Static variables are created when the class is loaded and persist as long as the class remains loaded. They're shared across all instances. Final variables are constants but can be instance or static. Only static has the class-lifetime behavior described in the question.

The JVM IS platform-dependent - each operating system needs its own JVM implementation (Windows JVM, Linux JVM, Mac JVM). However, Java bytecode (.class files) runs on ANY JVM, making Java programs platform-independent. The JVM itself must be platform-specific to bridge bytecode to native code.

Left shift operator (<<) multiplies by powers of 2. a << 2 shifts 64 left by 2 bits: 64 × 2^2 = 64 × 4 = 256. In binary: 64 = 1000000, shifting left gives 100000000 = 256. Each left shift doubles the value.

Math.random() is the standard Java method that returns a double between 0.0 and 1.0. Option B (getRandom) doesn't exist in Java API. Option C (setRandom) is not a standard method. Option D (random) alone isn't valid without Math. prefix.

The JVM performs automatic garbage collection to reclaim memory from objects no longer referenced. This is a key Java feature that prevents memory leaks. The OS manages system memory but doesn't know Java's object graph. Users don't manually trigger GC. The JDE is just a development tool bundle.

The code creates an ArrayList, adds 10, retrieves index 0, and prints it. This compiles and runs successfully, outputting 10. ArrayList stores Integer objects; get() returns an Integer which is auto-unboxed to int. No compilation or runtime errors occur.

The String.valueOf() method converts the integer 12345 to its string representation "12345". The original string "hello" is overwritten when str is reassigned. The output is simply the string "12345" printed to console.

The code performs simple integer addition: a=1, b=2, so c=a+b equals 3. The println statement concatenates "C=" with the value of c (3), producing "C=3" as output. There are no compilation or runtime errors.

A long value (99L) is explicitly cast to an int using (int) bvalue. Since 99 fits within the range of int (-2^31 to 2^31-1), the cast succeeds without data loss. The output is simply 99, not 99.0 or any decimal representation.