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When you define a set of conditions, you just have to write as many <condition> tags as you like.

Basic Condition Types

Dynamic Conditions

There is a number of built-in condition types in IzPack which can be used in an installation description, which are evaluated dynamically at a given moment as soon as they are referenced, depending on the installer state, the processed user inputs and the parameters given to them:

• CompareNumerics Condition
  Set when a certain comparison operation matches two numeric values.
• CompareVersions Condition
  Set when a certain comparison operation matches two version string values.
• Empty Condition
  True if a given value, file or directory is empty.
• Exists Condition
  True if a given variable, file or directory exists.
• Java Condition
  Set based on a static java field or method
• Packselection Condition
  Set when a certain pack is selected for installation.
• Ref Condition
  Set when a another, referenced condition is set.
• Variable Condition
  Set when a certain value matches the value of an IzPack variable.
• User Condition
  Set when a certain user is using the installer.

Aggregate Conditions

There are several aggregate conditions, which logically combine or alter one ore more conditions:

• And Condition
  All nested conditions have to be true.
• Or Condition
  At least one nested condition has to be true.
• Xor Condition
  Exactly one nested condition has to be true
• Not Condition
  The nested condition has to be false (negated state).

Pre-defined Conditions

There is a number of built-in conditions which are statically pre-set on launching the installation and which can be only referenced by their ID:

• izpack.windowsinstall
  True if the current OS is (any) Windows.
• izpack.windowsinstall.xp
  True if the current OS is Windows XP.
• izpack.windowsinstall.2003
  True if the current OS is Windows Server 2003.
• izpack.windowsinstall.vista
  True if the current OS is Windows Vista.
• izpack.windowsinstall.7
  True if the current OS is Windows 7.
• izpack.windowsinstall.8
  True if the current OS is Windows 8.
• izpack.macinstall
  True if the current OS is Mac OS X.
• izpack.linuxinstall
  True if the current OS is (any) Linux.
• izpack.solarisinstall
  True if the current OS is (any) Solaris.
• izpack.solarisinstall.x86
  True if the current OS is (any) Solaris x86.
• izpack.solarisinstall.sparc
  True if the current OS is (any) Solaris Sparc.

The following basic types of conditions can be used:

• Dynamic conditions
• Aggregate conditions
• Predefined conditions

See the links for more details.

Using Conditions

Defining Conditions

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Conditions are defined in the installation definition as nested <condition> elements of the <conditions/> element.

For example: 

• Dynamic Installer Requirements
• ConditionDataValidator
• Panels

<condition> - Attributes

The following attributes must be set in a <condition> element definition:

<condition> - Nested Elements

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<conditions>
    <condition type="variable" id="standardinstallation">
        <name>setup.type</name>
        <value>standard</value>
    </condition>
    <condition type="variable" id="expertinstallation">
        <name>setup.type</name>
        <value>expert</value>
    </condition>
    <condition type="java" id="installonwindows">
        <java>
            <class>com.izforge.izpack.util.OsVersion</class>
            <field>IS_WINDOWS</field>
        </java>
        <returnvalue type="boolean">true</returnvalue>
    </condition>
    <condition type="and" id="standardinstallation.onwindows">
        <condition type="ref" refid="standardinstallation"/>
        <condition type="ref" refid="installonwindows" />
    </condition>
</conditions>

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Referencing Conditions Referencing Conditions

Referencing Conditions

Conditions are referenced as optional attributes of several other elements in a installation definition or from IzPack resources:

• as condition attribute
• as conditionid attribute (for compatibility reasons of some tags)

Referencing A Number Of Conditions In One Expression

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Simple Expression Language Simple Expression Language

Simple Expression Language

From IzPack 3.11 on, you don't have to define compound conditions because you can use a simple expression language. The language supports the following operators:

These simple expressions DO NOT follow the usual boolean logic with precedence rules. Instead, they are evaluated left to right in a simple way.

Example:

{{\!conditionA+conditionB+\!conditionC}}

does not equal

{{(\!conditionA) && conditionB && (\!conditionC)}}

but is the same like

{{\!(conditionA && (conditionB && \!(conditionC)))}}

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Example:

<dynamicvariables>
    <variable name="db.instance" value="MSSQLSERVER" checkonce="true" condition="useMssql+mssqlInstanceSelected+!haveDatabaseURL" />
</dynamicvariables>

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Complex expression language Complex expression language

Complex expression language

Beginning with IzPack 5.0, there is also the possibility to use a more complex expression language which evaluates based on boolean precedence rules, which is also reflected in the following table. The higher an operator is, the higher is its precedence.

Example:

{{@!conditionA+&&conditionB+&&!conditionC}}

equals

{{(!conditionA) && conditionB && (!conditionC)}}

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In order to use the complex expression language the expression must start with a '@' character.

Example:

<dynamicvariables>
    <variable name="db.instance" value="MSSQLSERVER" checkonce="true" condition="@useMssql &amp;&amp; !haveDatabaseURL &amp;&amp; mssqlInstanceSelected" />
</dynamicvariables>