Package org.apache.tools.ant.filters

# Class ClassConstants

java.lang.Object
java.io.Reader
java.io.FilterReader
org.apache.tools.ant.filters.BaseFilterReader
org.apache.tools.ant.filters.ClassConstants

All Implemented Interfaces:
  `Closeable`, `AutoCloseable`, `Readable`, `ChainableReader`

public final class ClassConstants extends BaseFilterReader implements ChainableReader
Assembles the constants declared in a Java class in `key1=value1(line separator)key2=value2` format.

Notes:

1. This filter uses the BCEL external toolkit.
2. This assembles only those constants that are not created using the syntax `new whatever()`
3. This assembles constants declared using the basic datatypes and String only.
4. The access modifiers of the declared constants do not matter.

Example:

    <classconstants/>

Or:

    <filterreader
        classname="org.apache.tools.ant.filters.ClassConstants"/>

## Field Summary

### Fields inherited from class java.io.FilterReader

`in`

### Fields inherited from class java.io.Reader

`lock`

## Constructor Summary

Constructors
Constructor
Description
`ClassConstants()`
Constructor for "dummy" instances.
`ClassConstants(Reader in)`
Creates a new filtered reader.

## Method Summary

Modifier and Type
Method
Description
`Reader`
`chain(Reader rdr)`
Creates a new ClassConstants using the passed in Reader for instantiation.
`int`
`read()`
Reads and assembles the constants declared in a class file.

### Methods inherited from class org.apache.tools.ant.filters.BaseFilterReader

`getInitialized, getProject, read, readFully, readLine, setInitialized, setProject, skip`

### Methods inherited from class java.io.FilterReader

`close, mark, markSupported, ready, reset`

### Methods inherited from class java.io.Reader

`nullReader, read, read, transferTo`

### Methods inherited from class java.lang.Object

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

## Constructor Details

### ClassConstants

public ClassConstants()
Constructor for "dummy" instances.

See Also:
  - `BaseFilterReader()`

### ClassConstants

public ClassConstants(Reader in)
Creates a new filtered reader. The contents of the passed-in reader are expected to be the name of the class from which to produce a list of constants.

Parameters:
  `in` - A Reader object providing the underlying stream. Must not be `null`.

## Method Details

### read

public int read() throws IOException
Reads and assembles the constants declared in a class file.

Overrides:
  `read` in class `FilterReader`
Returns:
  the next character in the list of constants, or -1 if the end of the resulting stream has been reached
Throws:
  `IOException` - if the underlying stream throws an IOException during reading, or if the constants for the specified class cannot be read (for example due to the class not being found).

### chain

public Reader chain(Reader rdr)
Creates a new ClassConstants using the passed in Reader for instantiation.

Specified by:
  `chain` in interface `ChainableReader`
Parameters:
  `rdr` - A Reader object providing the underlying stream. Must not be `null`.
Returns:
  a new filter based on this configuration, but filtering the specified reader