Java Programming

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In closed subroutine a subroutine stored outside the main routine can be connected to it by linkages at one or more locations.

whereas in open subroutine is a set of computer instructions i.e. a subroutine that performs some particular program and insert them directly each and every time that particular function is required

The lang package contains classes for data types like Boolean, String etc and also some other classes like Thread.

http://java.sun.com/j2se/1.4.2/docs/api/java/lang/package-summary.html

Refer this for complete details.

Due to platform independence, a Java compiler will interpret Java source code into Java Byte Code and pass to the JVM, which will pass machine understandable code through to cpu. (clarification needed).A conventional compiler converts source code directly to machine code.(clarification needed).

SECR J class was created in 1913.

• OOP is a more complicated and structured paradigm than, say classic procedural programming.
• More planning and design is required on the programmer's part.
• OOP is less efficient in terms of a computer's resources than most other paradigms.
• OOP is a complex idea - no language including Java and C++ implements it perfectly.
• OOP may be overkill for smaller, simpler programs.

Embedded systems typically run on extremely limited hardware. Even the smallest implementation of Java (Micro Edition) can't compete with a small C implementation both in terms of memory footprint and execution speed.

import java.io.*;

class summ

{

public static void main()throws IOException

{

BufferedReader in=new BufferedReader(new InputStreamReader(System.in));

int a[]=new int[10];

int sum=0;

float avg=0;

for(int i=0;i<10;i++)

{

System.out.println("Enter marks of student "+(i+1)+" : ");

a[i]=Integer.parseInt(in.readLine());

sum+=a[i];

avg=sum;

}

avg/=10;

System.out.print("Sum= "+sum+"\nAverage= "+avg);

}

}

Yes, they are exactly the same, both of them increment k in 1.

class BackString

{

public static void main(String[] args)

{

//work out the length of args[]

int len=args.length;

//cycle forwards through the array string

for (int i=0; i<len; i++)

{

//how long is the word in characters?

int wordLen = args[i].length();

//cycle backwards through the word a char at a time

for (int j=wordLen-1; j>=0; j--)

{

System.out.print(args[i].charAt(j));

}

System.out.print(" ");

}

}

}

The implementation detail. Classes may provide a default implementation, interfaces provide only the method signatures

#include<stdio.h>

#include<conio.h>

#include<ctype.h>

main()

{

char string[80];

int n,k=0;

clrscr();

while((string[k]=getche())!='\r')

k++;

string[k]='\0';

n=k;

k=0;

while(k<n)

{

putchar(toupper(string[k]));

k++;

}

}

The default constructor is an empty (only call the super constructor) with no parameters constructor inserted by the java compiler when you don't define a constructor in your class. If you write something like this:

public class NoConstructorClass{

//no constructor goes here

}

Then you get something like this:

public class NoConstructorClass{

public NoConstructorClass(){ // Default constructor that you didn't write

super();

}

}

A default package is a package with no name. You can create a Java class without putting package name on top of the code. This class is included in the "default package".

Be careful not to be confused with java.lang, which is a package that contains Java's fundamental classes and get's imported by default.

You can download the Sun Java JRE Version 1.5.0_09 Here: http://java.sun.com/products/archive/j2se/5.0_09/index.html

Yes perfectly Legal

Reason:

The scope of a variable declared inside a method is only till the method's end. So by defining another variable of the same name inside a different method does not create any issues.

A Runnable Interface is one that is used to create a Java Thread...

A Thread can be created in two ways and using the Runnable Interface is one of them.

Example:

public class Test implements Runnable {

public void run(){

....

}

}

The Runnable interface would have an abstract instance of the method run() which needs to be implemented in the class which wants to create a Thread.

A constant in Java is defined using the "final" modifier. For instance:

final double Density_Of_Water = 1.000;

would set Density_Of_Water to 1.000. This value can not be modified throughout the program because "final" told the compiler that this value would not change. A variable however, can be changed by the user throughout the program.

By subtracting any two of the numbers A-B , if the output number is negative , B IS GREAT and if its positive A is great

System calls are much slower than APIs (library calls) since for each system call, a context switch has to occur to load the OS (which then serves the system call).

import java.io.*;

import java.util.*;

public class Calculator

{

public static void main(String args[])

{

System.out.println("Make your arithmetic selection from the choices below:\n");

System.out.println(" 1. Addition");

System.out.println(" 2. Subtraction");

System.out.println(" 3. Multiplication");

System.out.println(" 4. Division\n");

System.out.print(" Your choice? ");

Scanner kbReader = new Scanner(System.in);

int choice = kbReader.nextInt();

if((choice<=4) && (choice>0))

{

System.out.print("\nEnter first operand. ");

double op1 = kbReader.nextDouble();

System.out.print("\nEnter second operand.");

double op2 = kbReader.nextDouble();

System.out.println("");

switch (choice)

{

case 1: //addition

System.out.println(op1 + " plus " + op2 + " = " + (op1 + op2) );

break;

case 2: //subtraction

System.out.println(op1 + " minus " + op2 + " = " + (op1 - op2) );

break;

case 3: //multiplication

System.out.println(op1 + " times " + op2 + " = " + (op1 * op2) );

break;

case 4: //division

System.out.println(op1 + " divided by " + op2 + " = " + (op1 / op2) );

}

}

else

{

System.out.println("Please enter a 1, 2, 3, or 4.");

}

}

}

A Java Virtual Machine (JVM) is a set of computer software programs that use a virtual machine model for the execution of Java computer programs and scripts.

The JVM accepts data in a form commonly referred to as Java bytecode. This language conceptually represents the instruction set of a stack-oriented, capability architecture.