Class Declaration in Java

A simple Java class declaration with constructor declaration:

class simple
{
    // Constructor
    simple()
    {
         p = 1;
         q = 2;
         r = 3;
     }
         int p,q,r;
}

In class declaration, you can declare methods of the class:

class simple
{
    // Constructor
    simple()
    {
        p = 1;
        q = 2;
        r = 3;
     }
         int p,q,r;
     public int addNumbers(int var1, int var2, int var3)
     {
        return var1 + var2 + var3;
     }
    public void displayMessage()
    {
        System.out.println("Display Message");             }
}

To invoke the class, you can create the new instance of the class:
// To create a new instance class
Simple sim = new Simple();
// To access the methods of the class
sim.addNumbers(5,1,2)
// To show the result of the addNumbers
System.out.println("The result is " + Integer.toString(addNumbers(5,1,2)));

The complete listing of class declaration:

    class simple
     {
        // Constructor
        simple()
        {
             p = 1;
             q = 2;
             r = 3;
         }
             int p,q,r;
         public int addNumbers(int var1, int var2, int var3)
         {
            return var1 + var2 + var3;
         }
         public void displayMessage()
         {
             System.out.println("Display Message");
         }
     }

class example1
{
    public static void main(String args[])
     {
        // To create a new instance class
        Simple sim = new Simple(); // To show the result of the addNumbers
         System.out.println("The result is " + Integer.toString(addNumbers(5,1,2))); // To display message
         sim.displayMessage();
    }
}

Posted in: J2SE, Java