15.8

Class Instance Creation Expressions

EXPRESSIONS

15.8   Class Instance Creation Expressions

A class instance creation expression is used to create new objects that are

instances of classes.

ClassInstanceCreationExpression:

new

ClassType

 (

ArgumentList

opt

 )

ArgumentList:

Expression

ArgumentList

 ,

Expression

In a class instance creation expression, the

ClassType

must name a class that

is not

abstract

. This class type is the type of the creation expression.

The arguments in the argument list, if any, are used to select a constructor

declared in the body of the named class type, using the same matching rules as for

method invocations ( 15.11). As in method invocations, a compile time method

matching error results if there is no unique constructor that is both applicable to

the provided arguments and the most specific of all the applicable constructors.

15.8.1   Run time Evaluation of Class Instance Creation Expressions

At run time, evaluation of a class instance creation expression is as follows.

First, space is allocated for the new class instance. If there is insufficient space

to allocate the object, evaluation of the class instance creation expression com 

pletes abruptly by throwing an

OutOfMemoryError

 ( 15.8.2).

The new object contains new instances of all the fields declared in the speci 

fied class type and all its superclasses. As each new field instance is created, it is

initialized to its standard default value ( 4.5.4).

Next, the argument list is evaluated, left to right. If any of the argument eval 

uations completes abruptly, any argument expressions to its right are not evalu 

ated, and the class instance creation expression completes abruptly for the same

reason.

Next, the selected constructor of the specified class type is invoked. This

results in invoking at least one constructor for each superclass of the class type.

This process can be directed by explicit constructor invocation statements ( 8.6)

and is described in detail in  12.5.

The value of a class instance creation expression is a reference to the newly

created object of the specified class. Every time the expression is evaluated, a

fresh object is created.

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