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In Java, the standard way to create an object is using
MyClass name = new MyClass(); I also often see the construct
new MyClass() { /*stuff goes in here*/ }; I've been looking online for a while and can't find a good explanation of what the second construct style does or how it does it.
Can someone please explain how and why you would use the second construct?
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The Object constructor turns the input into an object. Its behavior depends on the input's type. If the value is null or undefined , it will create and return an empty object. Otherwise, it will return an object of a Type that corresponds to the given value. If the value is an object already, it will return the value.
When you create an object, you are creating an instance of a class, therefore "instantiating" a class. The new operator requires a single, postfix argument: a call to a constructor. The name of the constructor provides the name of the class to instantiate. The constructor initializes the new object.
Constructor functions or, briefly, constructors, are regular functions, but there's a common agreement to name them with capital letter first. Constructor functions should only be called using new .
Creating an Object Declaration − A variable declaration with a variable name with an object type. Instantiation − The 'new' keyword is used to create the object. Initialization − The 'new' keyword is followed by a call to a constructor. This call initializes the new object.
This construct makes actually two things: 1) It declares an anonymous class which extends the class you use in the constructor and 2) creates an instance of this anonymous class.
Edit: When using such a construct you can observe the anonymous class by looking at the generated .class files. There is the normal MyClass.class file and another one for each anonymous subclass: MyClass$1.class for the first and so on.
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