org.apache.wicket.util.string.interpolator

Class VariableInterpolator

java.lang.Object

org.apache.wicket.util.string.interpolator.VariableInterpolator

All Implemented Interfaces:

Serializable, IClusterable

Direct Known Subclasses:

MapVariableInterpolator, PropertyVariableInterpolator

public abstract class VariableInterpolator
extends Object
implements IClusterable

Base class for variable interpolators. An interpolator substitutes values into a String. So, a variable interpolator substitutes the values of one or more variables into a String.

The String to interpolate (substitute into) is passed to the VariableInterpolator's constructor. Variables are denoted in this string by the syntax ${variableName}. A subclass provides an implementation for the abstract method getValue(String variableName). The toString() method then performs an interpolation by replacing each variable of the form ${variableName} with the value returned by getValue("variableName").

"$" is the escape char. Thus "$${text}" can be used to escape it (ignore interpretation). If '$3.24' is needed then '$$${amount}' should be used. The first $ sign escapes the second, and the third is used to interpolate the variable.

Since:

1.2.6

Author:

Jonathan Locke

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected String	string The String to interpolate into

Constructor Summary

Constructors

Constructor and Description
VariableInterpolator(String string) Constructor.
VariableInterpolator(String string, boolean exceptionOnNullVarValue) Constructor.

Method Summary

Modifier and Type	Method and Description
protected abstract String	getValue(String variableName) Retrieves a value for a variable name during interpolation.
String	toString() Interpolates using variables.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

string

protected final String string

The String to interpolate into

Constructor Detail

VariableInterpolator

public VariableInterpolator(String string)

Constructor.

Parameters:

string - a String to interpolate with variable values

VariableInterpolator

public VariableInterpolator(String string,
                            boolean exceptionOnNullVarValue)

Constructor.

Parameters:

string - a String to interpolate with variable values

exceptionOnNullVarValue - if true an IllegalStateException will be thrown if getValue(String) returns null, otherwise the ${varname} string will be left in the String so that multiple interpolators can be chained

Method Detail

getValue

protected abstract String getValue(String variableName)

Retrieves a value for a variable name during interpolation.

Parameters:

variableName - a variable name

Returns:

the value

toString

public String toString()

Interpolates using variables.

Overrides:

toString in class Object

Returns:

the interpolated String