/** Program to call a constructor of a
class from another constructor */
class
ThisDemo3
{
int a,b;
ThisDemo3()
{
System.out.println("Inside constructor
without parameters");
a=10;
b=20;
}
ThisDemo3(int x)
{
a=x;
b=x;
System.out.println("Inside constructor
with one parameters");
}
ThisDemo3(int x,int y)
{
this(x);// x value passed to ThisDemo(int x)
System.out.println("Inside constructor
with two parameters");
}
public static void main(String args[])
{
ThisDemo3 t1=new ThisDemo3();
System.out.println("t1.a = " +
t1.a);
System.out.println("t1.b = " +
t1.b);
ThisDemo3 t2=new ThisDemo3(10,20);
System.out.println("t2.a = " +
t2.a);
System.out.println("t2.b = " +
t2.b);
}
}
NOTE:
1. 'this' keyword must
be used only in either constructors or non-static methods of a class. It cannot
be used in static methods of a class.
2. Writing two or more this call in
the same constructor is wrong.
Example:
class
Sample{
…..
……
}
Sample(int
a){
this();
this();
…..
…..
}
}//
it is wrong
3. Writing the this call as second
statement is also wrong
Example:
class Ramesh{
Ramesh(){
System.out.println(“I
am in cons”);
this(30);
}
System.out.println(“some
mess”);
}//
it is wrong
4. Recursive methods calls are allowed
in java but recursive constructor calls are not allowed in java.
Static and non-static
blocks:
These
are a set of statements that can be defined with the keyword static or without
static. Any block that starts with static keyword is called a static block.Its
syntax is:
static
{
---
}
->Any
block defined without a name or static keyword is called a non-static block.
Its syntax is :
{
----
}
