Does Coffee Decease Past Times Value Or Decease Past Times Reference - Interview Question
Tuesday, June 19, 2018
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Does Java is run past times past value or run past times past reference is i of the tricky Java question to a greater extent than oftentimes than non asked on fresher marking interviews. Before debating whether Java is run past times past value or run past times past reference lets starting fourth dimension clear what is run past times past value together with what is run past times past reference. This query has its rootage on C together with C++ where y'all tin run past times purpose parameter either value or retention address, where value is stored (pointer). As per Java specification everything inwards Java is run past times past value whether its primitive value or objects together with it does construct feel because Java doesn't back upwards pointers or pointer arithmetic, Similarly multiple inheritance together with operator overloading is besides non supported inwards Java. This query becomes confusing when interviewer inquire virtually how object is passed inwards Java ? Answer to this query is uncomplicated whenever a method parameter hold off object, reference of that object is passed. Many programmer confuses reference amongst pointers hither which is non correct, reference is a sort of grip which is used to locate object or modify object, but it doesn’t allows whatever pointer arithmetics i.e. y'all tin non increase or decrease retention address together with locate a unlike object using reference inwards Java.
Pass past times Value together with Pass past times Reference Example inwards Java
Let’s come across 2 event of calling method together with passing parameter this volition clear whatever dubiety whether Java is run past times past value or run past times past reference. catch next example: public class PassByValueExample {
public static void main(String args[]) {
int position out = 3;
printNext(number);
System.out.println("number Inside main(): "+number);
}
public static void printNext(int number){
number++;
System.out.println("number Inside printNext(): "+number);
}
}
Output:
position out Inside printNext(): 4
position out Inside main(): 3
public static void main(String args[]) {
int position out = 3;
printNext(number);
System.out.println("number Inside main(): "+number);
}
public static void printNext(int number){
number++;
System.out.println("number Inside printNext(): "+number);
}
}
Output:
position out Inside printNext(): 4
position out Inside main(): 3
Above event clearly shows that primitives are passed equally run past times past value to method parameters, had Java run past times past reference both main method and printNext() would convey printed same value. Now aspect at about other event of passing object equally method parameter which volition confuse y'all that Java is run past times past reference, which Java is not.
public class PassByReferenceConfusion {
public static void main(String args[]) {
Car machine = new Car("BMW");
System.out.println("Brand of Car Inside main() before: "+ car.brand);
printBrand(car);
System.out.println("Brand of Car Inside main()after: "+ car.brand);
}
public static void printBrand(Car car){
car.brand = "Maruti";
System.out.println("Brand of Car Inside printBrand(): "+car.brand);
}
private static class Car{
private String brand;
public Car(String brand){
this.brand = brand;
}
}
}
Output:
Brand of Car Inside main() before: BMW
Brand of Car Inside printBrand(): Maruti
Brand of Car Inside main()after: Maruti
public static void main(String args[]) {
Car machine = new Car("BMW");
System.out.println("Brand of Car Inside main() before: "+ car.brand);
printBrand(car);
System.out.println("Brand of Car Inside main()after: "+ car.brand);
}
public static void printBrand(Car car){
car.brand = "Maruti";
System.out.println("Brand of Car Inside printBrand(): "+car.brand);
}
private static class Car{
private String brand;
public Car(String brand){
this.brand = brand;
}
}
}
Output:
Brand of Car Inside main() before: BMW
Brand of Car Inside printBrand(): Maruti
Brand of Car Inside main()after: Maruti
If y'all come across change made inwards method parameter is reflected globally i.e. construct of machine is changed inwards all places it way i object is used inwards both method. Well inwards reality if y'all run past times object equally method parameter inwards Java it passes "value of reference" or inwards uncomplicated term object reference or grip to Object inwards Java. Here reference term is just unlike than reference term used inwards C together with C+ which straight points to retention address of variable together with champaign of written report to pointer arithmetic. inwards Java object tin just endure accessed past times its reference equally y'all tin non larn retention address where object is stored or to a greater extent than just at that spot is no method to larn value of object past times passing retention address.
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