Example 1: Java program to demonstrate the use of constructor
Codeaft.java
class Codeaft
{
    int i=0;
    public Codeaft()
    {
        i=i+1;
        System.out.println(i);
    }
    public static void main(String args[])
    {
        Codeaft c=new Codeaft();
        Codeaft c1=new Codeaft();
        Codeaft c2=new Codeaft();
    }
}
Output
codeaft@codeaft:~$ javac Codeaft.java
codeaft@codeaft:~$ java Codeaft
1
1
1
codeaft@codeaft:~$
Example 2: Java program to demonstrate the use of constructor
Codeaft.java
class Codeaft
{
    int a=20;
    Codeaft(int a)
    {
        a=a;
        System.out.println(a);
    }
    public static void main(String args[])
    {
        Codeaft c=new Codeaft(10);
    }
}
Output
codeaft@codeaft:~$ javac Codeaft.java
codeaft@codeaft:~$ java Codeaft
10
codeaft@codeaft:~$
Example 3: Java program to demonstrate the use of constructor
Codeaft.java
class Codeaft
{
    int a;
    Codeaft()
    {
        this(30);
    }
    Codeaft(int a)
    {
        this.a=a;
        System.out.println(a);
    }
    public static void main(String args[])
    {
        Codeaft c1=new Codeaft();
    }
}
Output
codeaft@codeaft:~$ javac Codeaft.java
codeaft@codeaft:~$ java Codeaft
30
codeaft@codeaft:~$
Example 4: Java program to demonstrate the use of constructor
Codeaft.java
class Shape
{
    public Shape()
    {
        System.out.println("1");
        new Shape(10);
        System.out.println("2");
    }
    public Shape(int side)
    {
        System.out.println("3");
        new Shape(10,20);
        System.out.println("4");
    }
    public Shape(int width, int breadth)
    {
        System.out.println("5");
    }
}
class Codeaft
{
    public static void main(String args[])
    {
        Shape s=new Shape();
    }
}
Output
codeaft@codeaft:~$ javac Codeaft.java
codeaft@codeaft:~$ java Codeaft
1
3
5
4
2
codeaft@codeaft:~$
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