Because you can change the value later for the same instance. For example, let’s assume a person with the following class: public class Person { String firstName; String lastName; public Person(String firstName, String lastName) { this.firstName = firstName; this.lastName = lastName; } public void setLastName(String lastName) { this.lastName = lastName; } } Imagine there is … Read more
If the goal is truly to have a complex number calculator, and not to complete a school assignment or other exercise with some arbitrary restrictions, then you should use std::complex and do not reinvent the wheel. For what it’s worth, the constructor of std::complex takes two arguments, both with default values. Not mentioning templates, std::complex< … Read more
In Java, you cannot define a constructor outside of a class.
read the message of the error of the compiler! Implicit super constructor Base() is undefined. Must explicitly invoke another constructor your child class must call the constructor of the parent class Child(int b) { super(b); this.b = b; }
The member is private, you get the error where you’re trying to print it, outside of the class. Simple enough, first all of the default values are assigned (constructed, see comment), then the code inside the constructor is executed. That’s why you see the 5 inside the constructor. If you want the constructor to change … Read more
I am not sure what you are trying to achive, but regarding your compilation issue, I notice two errors in your code: Remove the call super(texte) from Time constructor, as the class doesn’t extend any other class, so you cannot invoke any constructor of superclass. The constructor Time(Build, String) accept a Build instance as first … Read more
You need to add instance variables for the four fields, then use these in your code. So in the constructor you would be setting the values for these instance variables (these values will be sent to the constructor generally from another class). private String description; private String dept; private int units; private double price; public … Read more
this(0); is an example of constructor delegation. Here you’re calling, from a constructor, the constructor that takes an pair of ints as an argument. To exploit this idiom, the call to another constructor must be the first statement of the calling constructor. The rest of the behaviour is adequately explained with a line by line … Read more
Firstly if you want to equal “value” TO “a”, you must write: this.value = a; in Java (and a lot of programming languages), you must write variable that you change before equal mark. Second, if you will make “value” Integer. You must change it to int first: try { this.value = Integer.parseInt(a); } catch (NumberFormatException … Read more
public class Coffee { //Instance Variables private double sugar; private int milk; private boolean isHot; // renamed heat to isHot private int size; // Constructor public Coffee (double id, int dairy, boolean temp ) { sugar = id; milk = dairy; heat = temp; } // (setter) public void setSugar(double id) { this.sugar = id; … Read more