java Archives - Page 6 of 6

Java Argument Passing

November 8, 2019August 27, 2018 by manish

In Java, there are two ways of argument passing. Call by value Call by reference Call by value Whenever we call a method and passes the value of the variable to the called method, it’s called call by value.

class Demo {

    void set(int i, int j) {
        i = i * 2;
        j = j / 2;
    }
}

public class Test {

    public static void main(String arg[]) {
        Demo obj = new Demo();
        int a = 15, b = 20;

        System.out.println("Before call a=" + a + "  b=" + b);     		
		obj.set(a, b);
       System.out.println("After call a="+a+" "+" b="+b);
    }											                          
}

class Demo {

void set(int i, int j) {

i = i * 2;

j = j / 2;

}

public class Test {

public static void main(String arg[]) {

Demo obj = new Demo();

int a = 15, b = 20;

System.out.println("Before call a=" + a + " b=" + b);

obj.set(a, b);

System.out.println("After call a="+a+" "+" b="+b);

}

Result

Before call a=15  b=20
After call a=15  b=20

1 2	Before call a=15 b=20 After call a=15 b=20

Note: After multiplication and division value of a and b remain unchanged. … Read more

this keyword in java

November 8, 2019August 25, 2018 by manish

Local Variable Hides Instance Variable In java when the local variable has the same name as an instance variable, the local variable hides the instance variable.

public class Test {

    int a=10, b=10;// instance variable a,b	

    public static void main(String agrs[]) {
        Test t = new Test();
        t.display();
    }

    public void display() {
        int a = 5;//local variable same name as instance variable
        System.out.println("Value of local variable a=" + a);
        System.out.println("Value of instance variable a=" + a + " b=" + b);

    }
}

public class Test {

int a=10, b=10;// instance variable a,b

public static void main(String agrs[]) {

Test t = new Test();

t.display();

}

public void display() {

int a = 5;//local variable same name as instance variable

System.out.println("Value of local variable a=" + a);

System.out.println("Value of instance variable a=" + a + " b=" + b);

}

Result

Value of local variable a=5

Value of instance variable a=5 b=10

Value of local variable a=5

Value of instance variable a=5 b=10

In above program we have two instance variable with value a=10 and b=10. in method display there is a local variable a with value 5. Inside … Read more

Constructors in Java- Type Overloading and examples

March 7, 2021August 25, 2018 by manish

A Constructor in a special method that is used to initialize the object. Constructor name should be same as class name. Constructors does not have any return type.

public class Student(){
   //constructor   
   Student(){
    
   }
}

public class Student(){

//constructor

Student(){

}

While creating object of above class we use

Student student=new Studet()

1	Student student=new Studet()

Here new is used to create object and after then the constructor Student() is get called it … Read more

Java Classes and Objects

November 8, 2019August 23, 2018 by manish

Class A class forms the basis for object-oriented programming. It defines the shape and nature of the object. Any concept that we want to implement in oop’s must be encapsulated within a class. A class is a template for an object and an object is an instance for a class. In another words class is … Read more

Java Keywords

April 30, 2022August 18, 2018 by manish

Java contains 53 reserved words out of which 50 are keywords. Out of 50, only 48 keywords are used and two keywords const and goto are not in use, and 3 are literals values true, false, and null. These reserved words can not be used as identifiers. Java Keywords The keyword is a reserved word that … Read more