Constructor-

Definition-
Constructor is used to construct the objects.
-It initialize default or given values to object.

Syntax-

modifiers ClassName(parameters) {
//Constructor body
}

Rules of creation-
1- Constructor Name should be same as class name.

Rules of implementation-
1- constructor always should be followed by new keyword.

classesconst

Types of constructor-
1- Non Parameterized constructor
2– Parameterized constructor

1- Non Parameterized
(i)Default constructor-
Only when no constructor is created in class, compiler adds default constructor.

Syntax- created by compiler in compiled code-  constructorName(){
}

(ii) Manual Constructor-
Constructor created with no parameters.
It can have statements in constructor body.

Syntax - modifiers constructorName(){
Statements
}

2- Parameterized Constructor-
Constructor created with parameters.
It also can have statements in constructor body.

Syntax- modifiers constructotName(parameters) {
Statements
}

Methods-

metho is a set of statements to perform operations

Syntax –

Modifiers returnType methodName(parameters) {
//statements
}

Note- ReturnType= datatypes + void

code samples are here

1-Program to use default constructor(automatic creation)-


package constructors3;

public class Const1 {

public static void main(String[] args) {
 Const1 c1 = new Const1();
 }
}

2-Program to create  manual constructor which prints “a” and then use this manual constructor –

package constructors3;

public class Const2 {

public Const2() {
System.out.println("a");
}

public static void main(String[] args) {
Const2 c1 = new Const2();
}
}

3-Program to create parameterized constructor which takes String s as parameter and then use it by giving “Got it” as argument –


package constructors3;

public class Const3 {

public Const3(String s) {
System.out.println(s);
}

public static void main(String[] args) {
Const3 name = new Const3("Got it");
}

}
4-Program to create more than 1 constructor with different parameters then use all constructors by giving arguments.


package constructors3;

public class Const4 {

public Const4(int i,String a) {
System.out.println(i+a);

}

public Const4(String a,int i) {
System.out.println(a+i);
}

public Const4(double h,char o) {
System.out.println(h+" "+o);
}

public static void main(String[] args) {
Const4 c = new Const4(6, "deep");
Const4 c1 = new Const4(65.45d, 'p');
Const4 c2 = new Const4("kaushik",10);
}
}
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