A @RequiredArgsConstructor will be generated if no constructor has been defined. The Project Lombok @Data page explains: @Data is like having implicit @Getter, @Setter, @ToString, @EqualsAndHashCode and @RequiredArgsConstructor annotations on the class (except that no constructor will be generated if any explicitly written constructor exists).
The parent class’ constructor needs to be called before the subclass’ constructor. This will ensure that if you call any methods on the parent class in your constructor, the parent class has already been set up correctly. What you are trying to do, pass args to the super constructor is perfectly legal, you just need … Read more
Yes, an abstract class can have a constructor. Consider this: abstract class Product { int multiplyBy; public Product( int multiplyBy ) { this.multiplyBy = multiplyBy; } public int mutiply(int val) { return multiplyBy * val; } } class TimesTwo extends Product { public TimesTwo() { super(2); } } class TimesWhat extends Product { public TimesWhat(int … Read more
If a constructor does not explicitly invoke a superclass constructor, the Java compiler automatically inserts a call to the no-argument constructor of the superclass. If the super class does not have a no-argument constructor, you will get a compile-time error. Object does have such a constructor, so if Object is the only superclass, there is … Read more
Java Error: The constructor is undefined – Read For Learn Skip to content Add this to your class: Please understand that default no-argument constructor is provided only if no other constructor is written If you write any constructor, then compiler does not provided default no-arg constructor. You have to specify one. Categories Java Tags constructor, … Read more
Note: Cloning the lists, isn’t the same as cloning the elements in the list. None of these approaches work the way you want them to: //1 people = new ArrayList<Cool>(other.people); //2 people = new ArrayList<Cool>(); for(Cool p : other.people) { people.add(p); } The approaches above will fill people such that it contains the same elements as other.people. However, … Read more
Yes, it is possible: public class Foo { private int x; public Foo() { this(1); } public Foo(int x) { this.x = x; } } To chain to a particular superclass constructor instead of one in the same class, use super instead of this. Note that you can only chain to one constructor, and it has to be the first … Read more
If this class is only a utility class, you should make the class final and define a private constructor: public final class FilePathHelper { private FilePathHelper() { //not called } } This prevents the default parameter-less constructor from being used elsewhere in your code. Additionally, you can make the class final, so that it can’t … Read more
