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Have you ever tried to print an object using System.out.println() ?
Most probably you must have tried printing a String or an Integer value which prints its value.
For example, let say for the following code
String s="Tom";System.out.println(s);It will print "Tom".
or
int i=10;System.out.println(i);
will print 10.
But what will it print in following scenario.
Let say there is a class Circle with a int variable of radius.
class Circle
{
int radius;
Circle(int radius)
{
this.radius=radius;
}
}
Now let say you make an object of class Circle and print it.
Circle c= new Circle(10);
System.out.println(c);
What should I expect to get printed now? Radius of the Circle or any other thing.
When you run this code, it will print the following.
Circle@15db9742
Why this? What is that number after @ sign and why that name of class.
When any object is printed under System.out.println(), it prints its response of toString().
toString() method
java.lang.Object- Alpha class or super class for all the class that exist in Java have a method with following signature.
public String toString()
By default java.lang.Object is designed to return the following
NameofClass@Hexcode(hashCode)
Hence the output,
Circle@15db9742
Then why is it printing it differently for String and Integer?
Simple!! They have overridden the toString() method.
Let say I want the output of Circle object when printed as "Radius=radiusValue", I will have to override the toString() method.
class Circle
{
int radius;
Circle(int radius)
{
this.radius=radius;
}
public String toString()
{
String x="Radius="+radius;
return x;
}
}
Now when you print the object of class Circle, output will be different.
Circle c=new Circle(24);
System.out.pritnln(c);
Output: Radius=24
