When does the Constructor gets called in java?

Question

When does the Constructor get called?

1. Before object creation.
2. During object creation.
3. After object creation.

Answer 1

At the byte code level.

1. An object is created but not initialised.
2. The constructor is called, passing the object as this
3. The object is fully constructed/created when the constructor returns.

Note: The constructor at the byte code level includes the initial values for variables and the code in the Java constructor. e.g.

int a = -1;
int b;

Constructor() {
   super();
   b = 2;
}

is the same as

int a;
int b;

Constructor() {
   super();
   a = -1;
   b = 2;
}

Also note: the super() is always called before any part of the class is initialised.

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On some JVMs you can create an object without initialising it with Unsafe.allocateInstance(). If you create the object this way, you can't call a constructor (without using JNI) but you can use reflections to initialise each field.