Java Interview Questions & Answers

Java Interview Questions & Answers
  1. Explain Some Assembly Controls?

    Answer :

    • BRA Branch; Motorola 680x0, Motorola 68300; short (16 bit) unconditional branch relative to the current program counter
    • JMP Jump; Motorola 680x0, Motorola 68300; unconditional jump (any valid effective addressing mode other than data register)
    • JMP Jump; Intel 80x86; unconditional jump (near [relative displacement from PC] or far; direct or indirect [based on contents of general purpose register, memory location, or indexed])
    • JMP Jump; MIX; unconditional jump to location M; J-register loaded with the address of the instruction which would have been next if the jump had not been taken
    • JSJ Jump, Save J-register; MIX; unconditional jump to location M; J-register unchanged
    • Jcc Jump Conditionally; Intel 80x86; conditional jump (near [relative displacement from PC] or far; direct or indirect [based on contents of general purpose register, memory location, or indexed]) based on a tested condition: JA/JNBE, JAE/JNB, JB/JNAE, JBE/JNA, JC, JE/JZ, JNC, JNE/JNZ, JNP/JPO, JP/JPE, JG/JNLE, JGE/JNL, JL/JNGE, JLE/JNG, JNO, JNS, JO, JS
    • Bcc Branch Conditionally; Motorola 680x0, Motorola 68300; short (16 bit) conditional branch relative to the current program counter based on a tested condition: BCC, BCS, BEQ, BGE, BGT, BHI, BLE, BLS, BLT, BMI, BNE, BPL, BVC, BVS
    • JOV Jump on Overflow; MIX; conditional jump to location M if overflow toggle is on; if jump occurs, J-register loaded with the address of the instruction which would have been next if the jump had not been taken

  2. What Is Assembly Condition Codes?

    Answer :

    Condition codes are the list of possible conditions that can be tested during conditional instructions. Typical conditional instructions include: conditional branches, conditional jumps, and conditional subroutine calls. Some processors have a few additional data related conditional instructions, and some processors make every instruction conditional. Not all condition codes available for a processor will be implemented for every conditional instruction.

  3. What Is Data Movement?

    Answer :

    Data movement instructions move data from one location to another. The source and destination locations are determined by the addressing modes, and can be registers or memory. Some processors have different instructions for loading registers and storing to memory, while other processors have a single instruction with flexible addressing modes.

  4. What Are Kinds Of Processors?

    Answer :

    Processors can broadly be divided into the categories of: CISC, RISC, hybrid, and special purpose.

  5. What Are Assembly Attributes?

    Answer :

    Attributes are declarative tags in code that insert additional metadata into an assembly.

  6. What Are The Types Of Assemblies?

    Answer :

    Assemblies are of two types: 

    1. Private Assemblies 
    2. Shared Assemblies

  7. Explain An Intermediate Language?

    Answer :

    Assemblies are made up of IL code modules and the metadata that describes them. Although programs may be compiled via an IDE or the command line, in fact, they are simply translated into IL, not machine code. The actual machine code is not generated until the function that requires it is called.

  8. What Is Assembly Language?

    Answer :

    Each personal computer has a microprocessor that manages the computer's arithmetical, logical, and control activities.

    Each family of processors has its own set of instructions for handling various operations such as getting input from keyboard, displaying information on screen and performing various other jobs. These set of instructions are called 'machine language instructions'.

    A processor understands only machine language instructions, which are strings of 1's and 0's. However, machine language is too obscure and complex for using in software development. So, the low-level assembly language is designed for a specific family of processors that represents various instructions in symbolic code and a more understandable form.

  9. What Are The Advantages Of Assembly Language?

    Answer :

    Having an understanding of assembly language makes one aware of:

    • How programs interface with OS, processor, and BIOS;
    • How data is represented in memory and other external devices;
    • How the processor accesses and executes instruction;
    • How instructions access and process data;
    • How a program accesses external devices.

    Other advantages of using assembly language are:

    • It requires less memory and execution time;
    • It allows hardware-specific complex jobs in an easier way;
    • It is suitable for time-critical jobs;
    • It is most suitable for writing interrupt service routines and other memory resident programs.

  10. What Are The Basic Features Of Pc Hardware?

    Answer :

    The main internal hardware of a PC consists of processor, memory, and registers. Registers are processor components that hold data and address. To execute a program, the system copies it from the external device into the internal memory. The processor executes the program instructions.

    The fundamental unit of computer storage is a bit; it could be ON (1) or OFF (0). A group of nine related bits makes a byte, out of which eight bits are used for data and the last one is used for parity. According to the rule of parity, the number of bits that are ON (1) in each byte should always be odd.

    So, the parity bit is used to make the number of bits in a byte odd. If the parity is even, the system assumes that there had been a parity error (though rare), which might have been caused due to hardware fault or electrical disturbance.

    The processor supports the following data sizes −

    • Word: a 2-byte data item
    • Doubleword: a 4-byte (32 bit) data item
    • Quadword: an 8-byte (64 bit) data item
    • Paragraph: a 16-byte (128 bit) area
    • Kilobyte: 1024 bytes
    • Megabyte: 1,048,576 bytes

  11. What Is Binary Number System?

    Answer :

    Every number system uses positional notation, i.e., each position in which a digit is written has a different positional value. Each position is power of the base, which is 2 for binary number system, and these powers begin at 0 and increase by 1.

    The value of a binary number is based on the presence of 1 bits and their positional value. So, the value of a given binary number is:

    1 + 2 + 4 + 8 +16 + 32 + 64 + 128 = 255

    which is same as 28 - 1.

  12. What Is Hexadecimal Number System?

    Answer :

    Hexadecimal number system uses base 16. The digits in this system range from 0 to 15. By convention, the letters A through F is used to represent the hexadecimal digits corresponding to decimal values 10 through 15.

    Hexadecimal numbers in computing is used for abbreviating lengthy binary representations. Basically, hexadecimal number system represents a binary data by dividing each byte in half and expressing the value of each half-byte. 

  13. What Is Local Environment Setup?

    Answer :

    Assembly language is dependent upon the instruction set and the architecture of the processor. In this tutorial, we focus on Intel-32 processors like Pentium. To follow this tutorial, you will need :

    • An IBM PC or any equivalent compatible computer
    • A copy of Linux operating system
    • A copy of NASM assembler program

    There are many good assembler programs, such as :

    • Microsoft Assembler (MASM)
    • Borland Turbo Assembler (TASM)
    • The GNU assembler (GAS)

    We will use the NASM assembler, as it is :

    • Free. You can download it from various web sources.
    • Well documented and you will get lots of information on net.
    • Could be used on both Linux and Windows.

  14. How To Installing Nasm?

    Answer :

    If you select "Development Tools" while installing Linux, you may get NASM installed along with the Linux operating system and you do not need to download and install it separately. For checking whether you already have NASM installed, take the following steps −

    • Open a Linux terminal.
    • Type whereis nasm and press ENTER.
    • If it is already installed, then a line like, nasm: /usr/bin/nasm appears. Otherwise, you will see just nasm:, then you need to install NASM.

    To install NASM, take the following steps :

    • Check The netwide assembler (NASM) website for the latest version.
    • Download the Linux source archive nasm-X.XX.ta.gz, where X.XX is the NASM version number in the archive.
    • Unpack the archive into a directory which creates a subdirectory nasm-X. XX.
    • cd to nasm-X.XX and type ./configure. This shell script will find the best C compiler to use and set up Makefiles accordingly.
    • Type make to build the nasm and ndisasm binaries.
    • Type make install to install nasm and ndisasm in /usr/local/bin and to install the man pages.

    This should install NASM on your system. Alternatively, you can use an RPM distribution for the Fedora Linux. This version is simpler to install, just double-click the RPM file.


  15. What Are The Assembly Program Sections?

    Answer :

    An assembly program can be divided into three sections −

    • The data section,
    • The bss section, and
    • The text section.

  16. What Is The Data Section?

    Answer :

    The data section is used for declaring initialized data or constants. This data does not change at runtime. You can declare various constant values, file names, or buffer size, etc., in this section.

    The syntax for declaring data section is:

  17. What Is The Bss Section?

    Answer :

    The bss section is used for declaring variables. The syntax for declaring bss section is :


  18. What Is The Text Section?

    Answer :

    The text section is used for keeping the actual code. This section must begin with the declaration global _start, which tells the kernel where the program execution begins.

    The syntax for declaring text section is:

       global _start

  19. What Are The Assembly Language Statements?

    Answer :

    Assembly language programs consist of three types of statements −

    • Executable instructions or instructions,
    • Assembler directives or pseudo-ops, and
    • Macros.

    The executable instructions or simply instructions tell the processor what to do. Each instruction consists of an operation code (opcode). Each executable instruction generates one machine language instruction.

    The assembler directives or pseudo-ops tell the assembler about the various aspects of the assembly process. These are non-executable and do not generate machine language instructions.

    Macros are basically a text substitution mechanism.

  20. What Is The Syntax Of Assembly Language Statements?

    Answer :

    Assembly language statements are entered one statement per line. Each statement follows the following format −

    [label]   mnemonic   [operands]   [;comment]

    The fields in the square brackets are optional. A basic instruction has two parts, the first one is the name of the instruction (or the mnemonic), which is to be executed, and the second are the operands or the parameters of the command.