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- Type Parameters:
K
- the type of the object that is the result of the conversion
- All Known Implementing Classes:
CommandLine.UseDefaultConverter
- Enclosing class:
- CommandLine
public static interface CommandLine.ITypeConverter<K>
When parsing command line arguments and initializing fields annotated with
@Option
or@Parameters
, String values can be converted to any type for which aITypeConverter
is registered.This interface defines the contract for classes that know how to convert a String into some domain object. Custom converters can be registered with the
CommandLine.registerConverter(Class, ITypeConverter)
method.Java 8 lambdas make it easy to register custom type converters:
commandLine.registerConverter(java.nio.file.Path.class, s -> java.nio.file.Paths.get(s)); commandLine.registerConverter(java.time.Duration.class, s -> java.time.Duration.parse(s));
Built-in type converters are pre-registered for the following java 1.5 types:
- all primitive types
- all primitive wrapper types: Boolean, Byte, Character, Double, Float, Integer, Long, Short
- any enum
- java.io.File
- java.math.BigDecimal
- java.math.BigInteger
- java.net.InetAddress
- java.net.URI
- java.net.URL
- java.nio.charset.Charset
- java.sql.Time
- java.util.Date
- java.util.UUID
- java.util.regex.Pattern
- StringBuilder
- CharSequence
- String
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description K
convert(String value)
Converts the specified command line argument value to some domain object.
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Method Detail
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convert
K convert(String value) throws Exception
Converts the specified command line argument value to some domain object.- Parameters:
value
- the command line argument String value- Returns:
- the resulting domain object
- Throws:
Exception
- an exception detailing what went wrong during the conversion. Any exception thrown from this method will be caught and shown to the end user. An example error message shown to the end user could look something like this:Invalid value for option '--some-option': cannot convert 'xxxinvalidinput' to SomeType (java.lang.IllegalArgumentException: Invalid format: must be 'x:y:z' but was 'xxxinvalidinput')
CommandLine.TypeConversionException
- throw this exception to have more control over the error message that is shown to the end user when type conversion fails. An example message shown to the user could look like this:Invalid value for option '--some-option': Invalid format: must be 'x:y:z' but was 'xxxinvalidinput'
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