8.6.4

Constructor Throws

CLASSES

work. The lack of

native

 constructors is an arbitrary language design choice that

makes it easy for an implementation of the Java Virtual Machine to verify that

superclass constructors are always properly invoked during object creation.

8.6.4   Constructor Throws

The

throws

 clause for a constructor is identical in structure and behavior to the

throws

 clause for a method ( 8.4.4).

8.6.5   Constructor Body

The first statement of a constructor body may be an explicit invocation of another

constructor of the same class, written as

this

 followed by a parenthesized argu 

ment list, or an explicit invocation of a constructor of the direct superclass, written

as

super

 followed by a parenthesized argument list.

ConstructorBody:

{

ExplicitConstructorInvocation

opt

BlockStatements

opt

 }

ExplicitConstructorInvocation:

this (

ArgumentList

opt

 ) ;

super (

ArgumentList

opt

 ) ;

It is a compile time error for a constructor to directly or indirectly invoke

itself through a series of one or more explicit constructor invocations involving

this

.

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 is implicitly assumed by the compiler to begin with a super 

class constructor invocation  

super();

 , an invocation of the constructor of its

direct superclass that takes no arguments.

Except for the possibility of explicit constructor invocations, the body of a

constructor is like the body of a method ( 8.4.5). A

return

 statement ( 14.15)

may be used in the body of a constructor if it does not include an expression.

In the example:

class Point {

int x, y;

Point(int x, int y) { this.x = x; this.y = y; }

}

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