Package org.apache.tools.ant.types.selectors.modifiedselector

# Interface Algorithm

All Known Implementing Classes:
  `ChecksumAlgorithm`, `DigestAlgorithm`, `HashvalueAlgorithm`, `LastModifiedAlgorithm`

public interface Algorithm
The Algorithm defines how a value for a file is computed. It must be sure that multiple calls for the same file results in the same value. The implementing class should implement a useful toString() method.

Since:
  Ant 1.6
Version:
  2003-09-13

## Method Summary

Modifier and Type
Method
Description
`String`
`getValue(File file)`
Get the value for a file.
`boolean`
`isValid()`
Checks its prerequisites.

## Method Details

### isValid

boolean isValid()
Checks its prerequisites.

Returns:
  true if all is ok, otherwise false.

### getValue

String getValue(File file)
Get the value for a file.

Parameters:
  `file` - File object for which the value should be evaluated.
Returns:
  The value for that file