Chapter 1: Java Classes and Interfaces

jaguar.util.<object>Holder class

Description

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

For components that use the Jaguar-JDBC type mappings, 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 Table 1-2.

<object>Holder(<object> initialValue)

Constructor that takes an initial value specified as initialValue. initialValue is an instance of the appropriate datatype as specified in Table 1-2.

Methods

value: The current value contained by the holder object. Table 1-2 lists the datatypes and default values for the value field.

Usage

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.

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

Methods

Usage

See also