Relationships in java

[Jagadamba]

Hi All

Can anyone help me to understand the concept of relationship in java?
What is 'Has a' and 'Is a' relationship of java? Can we apply relationships to the objects? What is the relationship between base and child class?

Please give answers to my queries....

[Katty]

Hi,

The relationships in java are very easy to understand ,see the below details regarding this:

"Is a" relationship:

when one class inherits from another class this type relationship is "Is a" type.

e.g. if parrot inherits from bird, we can say parrot is a bird.

"Has a" relationship:

when one object has a member variable which is a reference to another object.Then this type of relationship is called as "Has a" relationship in java.

e.g. class monkey { leg monkeyleg; //here leg is another object }

we can say a monkey has a leg.

[kelfro]

"Is-a" OR "inheritance" relationships shows a hierarchical relationship between classes of objects.This relationships also referred as "generalization". For reference see the below example:

An "animal" is a generalization of "lion", "cat", "monkey" and many others animals. Now We can say that animal is an abstraction of lion, cat, etc. we can also say that since lions are animal , in which they inherit all the properties which is common animals.

"Has-a" OR "composition" OR "associative" relationships shows that one object has a distinct communication relationship with another object.
For e.g, mango tree "has-a" tree.

I hope this will useful for you..

[Zecho]

Hi, The following program will show you the relationship between base and child class in the java:

#include <iostream>
#include <stdlib.h>
using namespace std;

class BaseClass {

public:
void f(float);
};

void BaseClass::f(float price)
{
cout << "the base class!\n";
cout << price * .075f;

}

class DerivedClass1:public BaseClass
{
public:
void f(float);

};
void DerivedClass1::f(float price)
{
cout << "the child class 1\n";
cout << price * .010f << endl;
}

class DerivedClass2:public BaseClass
{
public:
void f(float);

};

void DerivedClass2::f(float price)
{
cout << "the child class 2\n";
cout << price * .005f << endl;
}

int main()
{
DerivedClass1 myclass;
DerivedClass2 anotherclass;

myclass.f(100);
anotherclass.f(100);

return 0;
}