Page 211 - computer science (868) class 11
P. 211
Let us take the following example for the array arr:
int arr[]=new int[10];
8.11 this KEYWORD
The ‘this’ keyword indicates the current object of the class being referred to. It is generally used to distinguish between
the class attributes and parameters of a class, when they have the same names.
Let us take the following example:
class sum
{
int a, b, s;
void input(int a, int b)
{
this.a=a;
this.b=b;
}
void add(sum ob1, sum ob2)
{
this.a=ob1.a+ob2.a;
this.b=ob1.b+ob2.b;
s=this.a+this.b;
}
void show()
{
System.out.println("The result is "+s);
}
public static void main()
{
sum t1=new sum();
sum t2=new sum();
sum t3=new sum();
t1.input(4,3);
t2.input(2,1);
t3.add(t1,t2);
t3.show();
}
}
The output of the preceding program is as follows:
The result is 10
Here,
a. void input (int a, int b): The parameters and the data members are of the same name, which creates an identity
problem for the compiler. The compiler cannot understand which values of ‘a’ and ‘b’ are to be considered – the
parameters mentioned herein or the data members. So, when ‘this’ keyword is used with the data members, the
compiler clearly understands the values of ‘a’ and ‘b’ to be picked up for calculation.
b. void add (sum ob1, sum ob2): The objects in the parameters have the same instance variables that are there in the
current object. So, to differentiate between them, ‘this’ keyword is used, where ‘this’ refers to the current object.
8.12 CONSTRUCTOR
All the instance variables need to be initialised as soon as the object has been created. And this is done by the method
constructor.
209
Methods and Constructors 209

