Print/list public/protected/private constructors of class in java (example)

Leave a Comment / By Yogesh / February 26, 2017

Given a class in java containing public,private & protected contructors.
Get/list/print all constructors (prive,protected & public) of a class using Class.
- getConstructors method of Class will list all public constructors of given class.
- getDeclaredConstructors method of Class will list all private, protected & public constructors

No.	Method Name	Description
1	Constructor<?>[] getConstructors()	Returns an array containing Constructor objects reflecting all the public constructors of the class represented by this Class object.
2	Constructor<?>[] getDeclaredConstructors()	Returns an array of Constructor objects reflecting all the constructors declared by the class represented by this Class object.

1. Print/list public/protected/private constructors of class in java (example)

package org.learn.classes;
 
import java.lang.reflect.Constructor;
import java.util.Date;
 
class Vehicle {
    private String owner;
    private float cost;
    private String model;
 
    private Vehicle() {
 
    }
 
    protected Vehicle(String owner, float cost) {
        this.owner = owner;
        this.cost = cost;
    }
 
    public Vehicle(String owner, float cost, String model) {
        this.owner = owner;
        this.cost = cost;
        this.model = model;
    }
}
 
public class DemoGetClassConstructors {
 
    public static void main(String[] args) {
 
        final Constructor<?>[] allConstructors = Vehicle.class.getConstructors();
 
        System.out.println("1. Get public constructors of Vehicle class");
        for (Constructor constructor : allConstructors) {
            System.out.println(constructor);
        }
        System.out.println("2. End - public constructors of Vehicle class");
        System.out.println();
 
        System.out.println("3. Get all declared (private,protected,public) constructors of Vehicle class");
        final Constructor<?>[] declaredConstructors = Vehicle.class.getDeclaredConstructors();
        for (Constructor constructor : declaredConstructors) {
            System.out.println(constructor);
        }
        System.out.println("4. End - all declared constructors of Vehicle class");
    }
}

2. Output: public/protected/private constructors of class in java (example)

1. Get public constructors of Vehicle class
public org.learn.classes.Vehicle(java.lang.String,float,java.lang.String)
2. End get public constructors of Vehicle class
 
3. Get all declared (private,protected,public) constructors of Vehicle class
private org.learn.classes.Vehicle()
protected org.learn.classes.Vehicle(java.lang.String,float)
public org.learn.classes.Vehicle(java.lang.String,float,java.lang.String)
4. End Get all declared constructors of Vehicle class