FilterHelpAppendable

java.lang.Object
- org.apache.commons.cli.help.FilterHelpAppendable

All Implemented Interfaces:

java.lang.Appendable, HelpAppendable

Direct Known Subclasses:

TextHelpAppendable
```
public abstract class FilterHelpAppendable
extends java.lang.Object
implements HelpAppendable
```
An abstract implementation of HelpAppendable that writes output to an Appendable instance.
This class is the superclass of all classes that filter help appendables. These appendable sit on top of an existing appendable (the underlying appendable) which it uses as its basic sink of data, but possibly transforming the data along the way or providing additional functionality.

The class FilterHelpAppendable itself simply overrides all methods of HelpAppendable with versions that pass all requests to the underlying appendable. Subclasses of FilterHelpAppendable may further override some of these methods as well as provide additional methods and fields.

Implementation Note: This class is similar to FilterOutputStream in relation to OutputStream. We could further split FilterHelpAppendable into a FilterAppendable but that seems like YAGNI.

Since:

1.10.0

Field Summary

Fields
Modifier and Type Field Description

protected java.lang.Appendable output
The underlying appendable to be filtered.

Constructor Summary

Constructors
Modifier	Constructor	Description
`protected`	`FilterHelpAppendable(java.lang.Appendable output)`	Constructs an appendable filter built on top of the specified underlying appendable.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`FilterHelpAppendable`	`append(char ch)`
`FilterHelpAppendable`	`append(java.lang.CharSequence text)`
`FilterHelpAppendable`	`append(java.lang.CharSequence csq, int start, int end)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.commons.cli.help.HelpAppendable
appendFormat, appendHeader, appendList, appendParagraph, appendParagraphFormat, appendTable, appendTitle

- Field Detail
  - output
```
protected final java.lang.Appendable output
```
    The underlying appendable to be filtered.
- Constructor Detail
  - FilterHelpAppendable
```
protected FilterHelpAppendable(java.lang.Appendable output)
```
    Constructs an appendable filter built on top of the specified underlying appendable.
    
    Parameters:
    
    output - the underlying appendable to be assigned to the field this.output for later use, or null if this instance is to be created without an underlying stream.
- Method Detail
  - append
```
public FilterHelpAppendable append(char ch)
                            throws java.io.IOException
```
    Specified by:
    
    append in interface java.lang.Appendable
    
    Throws:
    
    java.io.IOException
  - append
```
public FilterHelpAppendable append(java.lang.CharSequence text)
                            throws java.io.IOException
```
    Specified by:
    
    append in interface java.lang.Appendable
    
    Throws:
    
    java.io.IOException
  - append
```
public FilterHelpAppendable append(java.lang.CharSequence csq,
                                   int start,
                                   int end)
                            throws java.io.IOException
```
    Specified by:
    
    append in interface java.lang.Appendable
    
    Throws:
    
    java.io.IOException