vd-from-string-parser

Modular utility to parse Java objects from String values.

This library supports a variety of common types and can be extended with custom parsers using Java’s Service Provider Interface (SPI).

This utility is used at vd-from-properties-parser to support parsing objects from Properties.

Features

• Built-in support for:
  • Primitive types and their wrappers (int, long, double, boolean, etc.)
  • BigInteger, BigDecimal
  • Pattern, Class, URL, URI
  • Enums
• Extensible via SPI (Service Provider Interface via META-INF/services)
• Simple, consistent API
• Validates and initializes custom parsers at runtime

---

Usage

FromStringParsers parsers = FromStringParsers.DEFAULT;

int number = parsers.parse("42", int.class);
URL url = parsers.parse("https://example.com", URL.class);
Pattern pattern = parsers.parse("\\d+", Pattern.class);
MyEnum value = parsers.parse("VALUE", MyEnum.class);

Adding Custom Parsers

To support custom types, implement the FromStringParser<T> interface:

public class MyTypeParser implements FromStringParser<MyType> {

    @Override
    public Class<MyType> getResultClass() {
        return MyType.class;
    }

    @Override
    public MyType parse(String string) throws ParseException {
        // convert string to MyType
    }
}

Register the parser using Java’s SPI mechanism:

1. Create a file named
   META-INF/services/de.voomdoon.parser.fromstring.FromStringParser

2. List your implementation class inside that file:

   com.example.MyTypeParser
   

Custom parsers are discovered and loaded automatically.

---

Error Handling

• If no parser is registered for a given type, parse throws UnsupportedOperationException.
• If a parser fails to declare its result class, an InvalidParserException is thrown during initialization.