Chapter 1 Java Classes and Interfaces

jaguar.util.<object>Holder class

Description

package com.sybase.jaguar.util;public class <object>Holder extends Object

Holder classes are used to pass INOUT parameters to component method calls. Each holder class has a value field that contains instances of a specific object or base Java type.

Additional holder classes are defined in packages com.sybase.jaguar.util.jdbc102 and com.sybase.jaguar.util.jdbc11.

com.sybase.jaguar.util holder classes are summarized in the Table 1-2.

Table 1-2: Holder classes
Holder class	Datatype for value field	Default for value
`BooleanHolder`	`boolean`	false
`ByteHolder`	`byte`	0
`BytesHolder`	`byte[]`	null
`CharHolder`	`char`	\u0000 (null character)
`FloatHolder`	`float`	0.0
`DoubleHolder`	`double`	0.0
`IntegerHolder`	`int`	0
`LongHolder`	`long`	0
`ShortHolder`	`short`	0
`StringHolder`	`java.lang.String`	null

WARNING!

Null parameter values are not supported. For StringHolder or BytesHolder parameters, use the constructor that takes an initial value, or set the value field explicitly.

Constructors

<object>Holder()

Default constructor that assigns the default value specified in "Holder classes".

<object>Holder(<object> initialValue)

Constructor that takes an initial value specified as initialValue. initialValue is an instance of the appropriate datatype as specified in "Holder classes".

value

The current value contained by the holder object. "Holder classes" lists the datatypes and default values for the value field.

Usage

Client stub classes must construct a holder object for each INOUT parameter to be passed in a method call. See Appendix C, "Creating EAServer 1.1 Java Clients" in the EAServer Programmer's Guide for information on calling stub classes.

Java component methods on the server receive INOUT parameters as a holder object. The method should set the value field of each holder object before returning. See the "Creating CORBA/Java Components" chapter in the EAServer Programmer's Guide for information on coding Java components.

The examples below illustrate how to construct and use holder objects:

Each holder object has a default constructor that takes no arguments. For example:

StringHolder str_holder = new StringHolder();
IntegerHolder int_holder = new IntegerHolder();

Each holder object has an additional constructor that takes an initial value as a parameter. For example:

StringHolder str_holder = 
                 new StringHolder("hello");
IntegerHolder int_holder = new IntegerHolder(43);

float f = 3.141;
FloatHolder float_holder = new FloatHolder(f);

Each holder object has a value member that allows access to the base object value. For example:

IntegerHolder i_hold = new IntegerHolder();
System.out.println(
  "IntegerHolder default value is:"
  + i_hold.value);

jaguar.util.<object>Holder class

Description

Constructors

Usage

See Also