TYPES, VALUES, AND VARIABLES

Objects

4.3.1

//

An array is implicitly created by an array constructor:

Point a[] = { new Point(0,0), new Point(1,1) };

// String

s are implicitly created by

+

 operators:

System.out.println("p: " + p);

System.out.println("a: { " + a[0] + ", "

+ a[1] + " }");

//

An array is explicitly created by an array creation expression:

String sa[] = new String[2];

sa[0] = "he"; sa[1] = "llo";

System.out.println(sa[0] + sa[1]);

}

}

which produces the output:

default

p: (0,0)

a: { (0,0), (1,1) }

hello

The operators on references to objects are:

Field access, using either a qualified name ( 6.6) or a field access expression

( 15.10)

Method invocation ( 15.11)

The cast operator ( 5.4,  15.15)

The string concatenation operator

+

 ( 15.17.1), which, when given a

String

operand and a reference, will convert the reference to a

String

 by invoking

the

toString

 method ( 20.1.2) of the referenced object (using

"null"

 if

either the reference or the result of

toString

 is a null reference), and then

will produce a newly created

String

 that is the concatenation of the two

strings

The

instanceof

 operator ( 15.19.2)

The reference equality operators

==

 and

!=

 ( 15.20.3)

The conditional operator

? :

 ( 15.24).

There may be many references to the same object. Most objects have state,

stored in the fields of objects that are instances of classes or in the variables that

are the components of an array object. If two variables contain references to the

same object, the state of the object can be modified using one variable's reference

to the object, and then the altered state can be observed through the reference in

the other variable.

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