picocli

Interface CommandLine.IFactory

Enclosing class:

CommandLine

public static interface CommandLine.IFactory

Factory for instantiating classes that are registered declaratively with annotation attributes, like CommandLine.Command.subcommands(), CommandLine.Option.converter(), CommandLine.Parameters.converter() and CommandLine.Command.versionProvider(). The factory is also used to instantiate the Collection or Map implementation class for multi-value options and positional parameters with an abstract type, like List<String>.

You may provide a custom implementation of this interface. For example, a custom factory implementation could delegate to a dependency injection container that provides the requested instance.

Custom factory implementations should always fall back to the default factory if instantiation failed. For example:

 class MyFactory implements IFactory {
     private final ApplicationContext applicationContext = getAppContext();

     public <T> T create(Class<T> cls) throws Exception {
         try {
             applicationContext.getBean(cls);
         } catch (Exception ex) {
             CommandLine.defaultFactory().create(cls);
         }
     }
 }
 

Tip: custom factory implementations that have resources that need to be closed when done should consider implementing java.lang.AutoCloseable or java.io.Closeable. This allows applications to use the following idiom for configuring picocli before running their application:

 public static void main(String[] args) {
     int exitCode = 0;
     try (MyFactory factory = createMyFactory()) {
         exitCode = new CommandLine(MyClass.class, factory)
                 .setXxx(x) // configure the picocli parser...
                 .execute(args);
     }
     System.exit(exitCode);
 }
 

Since:

2.2

See Also:

CommandLine.CommandLine(Object, IFactory), CommandLine.call(Class, IFactory, PrintStream, PrintStream, Help.Ansi, String...), CommandLine.run(Class, IFactory, PrintStream, PrintStream, Help.Ansi, String...), CommandLine.defaultFactory()

Method Summary

Modifier and Type	Method and Description
<K> K	create(Class<K> cls) Returns an instance of the specified class.

Method Detail

create

<K> K create(Class<K> cls)
      throws Exception

Returns an instance of the specified class.

Type Parameters:

K - the type of the object to return

Parameters:

cls - the class of the object to return

Returns:

the instance

Throws:

Exception - an exception detailing what went wrong when creating or obtaining the instance