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Jul 14, 2013 · Chaining constructors like this is useful to avoid repeating code, and helps with maintainability: public MyClass(int x, double y, String z) { // set fields } public MyClass() { // i.e. a constructor that uses default values this(42, 4.2, "hello world"); // x is 42, y is 4.2, and z is "hello world" }
Nov 12, 2008 · Calling a constructor from another constructor in Java is primarily a means of providing default values for parameters to the one constructor that should actually construct your object, and then it should be enough to just assign values in the constructor's body.
Nov 15, 2010 · The first constructor in chain actually overrides all previously set values. This is a reason why weight = 10 for the first object. Second object is created using 2-arg constructor that is called with parameters 10 and 20, so volume is 10*20*10 = 2000. (second 10 is set when 2args constructor calls 3args constructor.)
Dec 3, 2022 · If a constructor body does not begin with an explicit constructor invocation and the constructor being declared is not part of the primordial class Object, then the constructor body implicitly begins with a superclass constructor invocation "super();", an invocation of the constructor of its direct superclass that takes no arguments.
Apr 4, 2019 · When calling a method with a vararg parameter, you have a choice. You can pass in an array, or you can list the elements of the array and let Java create it for you. You can even omit the vararg values in the method call and Java will create an array of length zero for you.
Jul 23, 2009 · It also greatly increases the difficulty of safely chaining constructors which need to acquire resources and pass them to the parent constructor (the child constructor needs to invoked by a factory method that creates a container for the resources, invokes the constructor within a try block, and discards any resources in the container if the constructor fails.
Apr 28, 2013 · Java method call in constructor chaining. 1. Java Object Class, Constructor Chaining. 2. Java Constructor ...
Just do this, using a field that is set differently based on the constructor you called: public class ConstructorChaining { String a; int b; //This value is different for each constructor, so you can control your //toString implementation String asString; public ConstructorChaining() { this(""); } public ConstructorChaining(String a) { this(a, 0, a + ""); } public ConstructorChaining(String a, int b) { this(a, b, 0, a + "" + b); } private ConstructorChaining(String a, int b, String asString ...
make the default constructor private to prevent constructor instantiation and instantiate objects using a public static method. This way you can work around the constructor restriction. To add a little confusion I converted your constructors to normal methods using the class name by adding void return type. Also consider if want you really want ...
Apr 7, 2016 · Have one "main" constructor that fully handles the instance initialization; Have all the other constructors call it; Also I somewhat dislike long chaining (hard to get to the actual code if drilling down from a simple constructor), so I tend to write all other constructors to directly call the "main" one unless it means duplicate code.
