Passing object as Parameter in Java

We can pass local variables from one method to another method as parameter.

public class Pro
{
    public static void main(String args[])
    {
        int x=10; // 'x' is local in main
        System.out.println("x in main : " + x);
        Pro.test(x);
    }
    static void test(int x) // 'x' is argument(local)
    {
        System.out.println("x in test : " + x);
    }
}

Passing object as parameter:

• Like primitive data types, we can pass objects as parameters.
• We need to collect these parameters into Class type variables in called method.

public class Pro
{
    public static void main(String args[])
    {
        Pro x = new Pro(); // 'x' is local in main
        System.out.println("x in main : " + x);
        Pro.test(x);
    }
    static void test(Pro x) // 'x' is argument(local)
    {
        System.out.println("x in test : " + x);
    }
}

Integer static variable default value is ‘0’.

public class Pro
{
    static int x;
    static
    {
        System.out.println("x value in block : " + Pro.x);
        Pro.x = 10;
    }
    public static void main(String args[])
    {
        System.out.println("x value in main : " + Pro.x);
    }
}

• Class type variable default value is ‘null’.
• It holds address of that object.
• ‘Pointer variable’ holds address.

public class Pro
{
    static Pro x;
    static
    {
        System.out.println("x value in block : " + Pro.x);
        Pro.x = new Pro();
    }
    public static void main(String args[])
    {
        System.out.println("x value in main : " + Pro.x);
    }
}