Default Constructor : If you are going to instantiate an array of objects of the class, the class must have a defaultand constructor. If no user-defined constructor exists for a class A and one is needed, the compiler implicitly declares a default parameter less constructorand A::A() .and Syntax:class X {and public: and X(); // Default constructor with no arguments and X(int = 0); // Default constructor with one default argument and X(int, int , int = 0); // Constructor }; Ex: // Main.javaand class Test { and and int i; and and Test t; and and boolean b; and and byte bt; and and float ft; } public class Main { and and public static void main(String args[]) { and and and Test t = new Test(); // default constructor is called. and and and System.out.println(t.i); and and and System.out.println(t.t); and and and System.out.println(t.b); and and and System.out.println(t.bt); and and and System.out.println(t.ft); and and } }

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Default Constructor

Anonymous User 1096 20-Jun-2018

What Is A Default Constructor ?

java

Updated on 20-Jun-2018

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Prakash nidhi Verma

20-Jun-2018

Default Constructor :

If you are going to instantiate an array of objects of the class, the class must have a default constructor. If no user-defined constructor exists for a class A and one is needed, the compiler implicitly declares a default parameter less constructor A::A() .

Syntax:

class X { 
public:

  X();                       // Default constructor with no arguments

  X(int = 0);                // Default constructor with one default argument

  X(int, int , int = 0);     // Constructor

};

Ex:

// Main.java 
class Test {
   int i;
   Test t;
   boolean b;
   byte bt;
   float ft;
}
public class Main {
    public static void main(String args[]) {
      Test t = new Test(); // default constructor is called.
      System.out.println(t.i);
      System.out.println(t.t);
      System.out.println(t.b);
      System.out.println(t.bt);
      System.out.println(t.ft);
    }
}

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Default Constructor

Anonymous User

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