Constructor Overloading in Java
Constructor Overloading in java is allowing a class to have more than one constructor with each taking different parameters.
Example
public class Student {
String name;
int studentID;
String gender;
Student(String s,int id)
{
name=s;
studentID=id;
}
Student(String s,String g,int id)
{
name=s;
gender=g;
studentID=id;
}
void showDetails()
{
System.out.println("Student name is " +name);
System.out.println("Student ID is " +studentID);
System.out.println("Student gender is " +gender);
}
public static void main(String args[])
{
Student s =new Student("Eric Mutua",222221);
s.showDetails();
Student s2=new Student("Jane Kate","Female",232222);
s2.showDetails();
}
}
Output:
Student name is Eric Mutua
Student ID is 222221
Student gender is null
Student name is Jane Kate
Student ID is 232222
Student gender is Female
BUILD SUCCESSFUL (total time: 0 seconds)
Java Copy Constructor
There are three ways of copying java object values into another java object.These are:-
- By constructor
- By assigning the values of one object into another
- By clone() method of Object class
Below example shows how to copy from one object to another using Java Constructor.
public class Student {
String name;
int studentID;
Student(String s,int id)
{
name=s;
studentID=id;
}
Student(Student s)
{
name=s.name;
studentID=s.studentID;
}
void showDetails()
{
System.out.println("Student name is " +name);
System.out.println("Student ID is " +studentID);
}
public static void main(String args[])
{
Student s =new Student("Eric Mutua",222221);
s.showDetails();
Student s2=new Student(s);
s2.showDetails();
}
}
Output
run:
Student name is Eric Mutua
Student ID is 222221
Student name is Eric Mutua
Student ID is 222221
BUILD SUCCESSFUL (total time: 0 seconds)
Copying values without constructor
Its possible to copy values of one object and assign them to another object
Example:
public class Student {
String name;
int studentID;
Student(String s,int id)
{
name=s;
studentID=id;
}
Student()
{
}
void showDetails()
{
System.out.println("Student name is " +name);
System.out.println("Student ID is " +studentID);
}
public static void main(String args[])
{
Student s =new Student("Eric Mutua",222221);
s.showDetails();
Student s2=new Student();
s2.name=s.name;
s2.studentID=s.studentID;
s2.showDetails();
}
}
