VariableInterpolator (Wicket Util 9.0.0-SNAPSHOT API)

java.lang.Object
- org.apache.wicket.util.string.interpolator.VariableInterpolator

All Implemented Interfaces:

java.io.Serializable, IClusterable

Direct Known Subclasses:

MapVariableInterpolator
```
public abstract class VariableInterpolator
extends java.lang.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 Description

protected java.lang.String string
The String to interpolate into

Constructor Summary

Constructors
Constructor	Description
`VariableInterpolator(java.lang.String string)`	Constructor.
`VariableInterpolator(java.lang.String string, boolean exceptionOnNullVarValue)`	Constructor.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`protected abstract java.lang.String`	`getValue(java.lang.String variableName)`	Retrieves a value for a variable name during interpolation.
`java.lang.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 java.lang.String string
```
    The String to interpolate into
- Constructor Detail
  - VariableInterpolator
```
public VariableInterpolator(java.lang.String string)
```
    Constructor.
    
    Parameters:
    
    string - a String to interpolate with variable values
  - VariableInterpolator
```
public VariableInterpolator(java.lang.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 java.lang.String getValue(java.lang.String variableName)
```
    Retrieves a value for a variable name during interpolation.
    
    Parameters:
    
    variableName - a variable name
    
    Returns:
    
    the value
  - toString
```
public java.lang.String toString()
```
    Interpolates using variables.
    
    Overrides:
    
    toString in class java.lang.Object
    
    Returns:
    
    the interpolated String