Author: Satish

Using Constructors & Member Function to add two numbers: Java

In this Java video tutorial we have covered both ways of adding numbers: using constructors as well as using methods.

Constructors:

Constructor name and the class name must be same.
No return type.
There are 3 types of constructors:
1. Default constructors.
2. Parameterized constructors.
3. Copy Constructors.

In this video tutorials we have shown the use of Parameterized constructors.

calc(int a, int b)
{
no1 = a;  
no2 = b;  
}

Adding and displaying the result:

public void sum()
{
System.out.println("Sum of "+no1+" and "+no2+" is "+(no1+no2));
}

Strings are written inside double quotes and the variables written outside the double quotes will display the value stored in them.
+ (plus) is concatenation operation.
(no1+no2) adds the value present in no1 and no2 and displays the result of addition.

Video Tutorial



YouTube Link: https://www.youtube.com/watch?v=gUXq1psurdk [Watch the Video In Full Screen.]



Object Creation:

/* calc c; // object declaration. It will have null in it.
   c = new calc(20,10); // Construction call
*/ 
   calc c = new calc(30, 10);

Full Java code: Using Constructors & Member Function to add two numbers(add.java)

import java.lang.*;
 
class calc
{
int no1, no2;
 
calc(int a, int b)
{
no1 = a;  // 30
no2 = b;  // 10
}
 
/*
public void assign(int a, int b)
{
no1 = a;  // 30
                no2 = b;  // 10
}
*/ 
public void sum()
{
System.out.println("Sum of "+no1+" and "+no2+" is "+(no1+no2));
}
}
 
class add
{
public static void main(String args[])
{
/* calc c; // object declaration. It will have null in it.
c = new calc(20,10); // Construction call
*/ 
calc c = new calc(30, 10);
//c.assign(30,10);
c.sum();
}
}

Member functions are called with the help of object.
Syntax:
object.memberfuntion();

First Java Program: Basic

This Java tutorial will illustrate the basics of all java programs.

class Welcome

Class is a keyword. Welcome is an identifier or name of the class.
Class Welcome is declaration of class.

class Welcome
{

}

Every class definition in Java begins with an opening brace and ends with a matching closing brace. Note that there is no ending semicolon in Java unlike in C++.

public static void main(String args[])
{
System.out.println("Welcome To Java!");
}

main() is the starting point for the interpreter to begin execution of the program. A java application can have any number of classes but only one of them must include a main method.
void: since main does not return any value;
static: Java is a pure object oriented programming language and hence even main is written inside of a class. main() belongs to the entire class and not a part of any objects of the class, so main is declared as static.
public: methods with public access specification can be accessed even outside the class.

String: is a built-in class, present inside java.lang package.
args[] : is a array variable, used to get the arguments from the user.

System.out.print() or System.out.println() is similar to printf() in C or cout>> in C++.
print() or println() method is a member of the out object, which is a static data member of System class.

Full Java code to print “Welcome to Java!” (Welcome.java)

class Welcome
{
public static void main(String args[])
{
System.out.println("Welcome To Java!");
}
}

Video Tutorial


YouTube Link: https://www.youtube.com/watch?v=lXaFnboq3sk [Watch the Video In Full Screen.]


YouTube Link: https://www.youtube.com/watch?v=ePG4GE3hmbY [Watch the Video In Full Screen.]



Please watch the above video tutorial in full screen.