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What are the differences between default constructor and parameterized constructor in Java?
Default Constructor
- A default constructor is a 0 argument constructor which contains a no-argument call to the super class constructor.
- To assign default values to the newly created objects is the main responsibility of default constructor.
- Compiler writes a default constructor in the code only if the program does not write any constructor in the class.
- The access modifier of default constructor is always the same as a class modifier but this rule is applicable only for “public” and “default” modifiers.
When will compiler add a default constructor
- The compiler adds a default constructor to the code only when the programmer writes no constructor in the code.
- If the programmer writes any constructor in the code, then the compiler doesn't add any constructor.
- Every default constructor is a 0 argument constructor but every 0 argument constructor is not a default constructor.
Parameterized Constructors
- The parameterized constructors are the constructors having a specific number of arguments to be passed.
- The purpose of a parameterized constructor is to assign user-wanted specific values to the instance variables of different objects.
- A parameterized constructor is written explicitly by a programmer.
- The access modifier of default constructor is always the same as a class modifier but this rule is applicable only for “public” and “default” modifiers.
Example
public class Student {
int roll_no;
String stu_name;
Student(int i, String n) { // Parameterized constructor
roll_no = i;
stu_name = n;
}
void display() {
System.out.println(roll_no+" "+stu_name);
}
public static void main(String args[]) {
Student s1 = new Student(1,"Adithya");
Student s2 = new Student(2,"Jai");
s1.display();
s2.display();
}
}In the above program, the programmer defines one parameterized constructor with 2 parameters. Now the compiler adds no default constructor to the code, and nor the programmer has written any 0 argument constructor.
Output
1 Adithya 2 Jai
Updated on: 06-Feb-2020
8K+ Views
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