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Java Inter-op.md

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Java Inter-op

bjForth provides three pairs of words (primitives) to tap into the power of JVM.

Constructors

The @< primitive parses the specification of the constructor and >@ executes the given constructor and pushes the result onto ParameterStack.

The specification for the constructor consists of 3 distinct pieces:

  • The class. It can be a fully qualified type name or in case the class resides in any of java.lang, java.util or java.io packages it can be a short (simple) name.
  • Parameter types. The types are treated in the same way as the class above.
  • Arity. It denotes how many elements from ParameterStack should be popped.

NOTE 1: The parameter types must be identical to those of the constructor declaration. NOTE 2: There is an arbitrary limit to the number of non-variadic arguments for a variadic method call. It's 7! Note that this doesn't apply to non-variadic methods!

Examples

  • Create a string (pretty useless though as strings are native to bjForth via ." and ". words.
." Hello, world ". @< String(String)/1
  • Constructor with a variadic argument
package mypackage.other;

import mypackage.Bar;

public class Foo {
  public Foo(String, File, Bar...);   
}
<a Bar instance> <another Bar instance> <a File> <a String> @< mypackage.other.Foo(String, File, mypackage.Bar...)/4 >@

Instance methods

The .< parses the specification of the constructor and >. executes the given method and pushes the result onto ParameterStack.

The specification for the constructor is composed of 2 distinct pieces:

  • Parameter types. The types are treated in the same way as the the class above.
  • Arity. It denotes how many elements from ParameterStack should be popped.

NOTE: The parameter types must be identical to those of the constructor declaration.

Examples

  • Get the Long value of a given integer.
24 .< longValue()/0 >.
  • Method with a variadic argument
package mypackage.other;

import mypackage.Bar;

public class Foo {
  public foo(String, File, Bar...);   
}
<a Bar instance> <another Bar instance> <a File> <a String> <a Foo instance> .< foo(String, File, mypackage.Bar...)/4 >.

Static methods

The ,< primitive parses the specification of the static method and >, executes the given method and pushes the result onto ParameterStack.

The specification for the constructor consists of 3 distinct pieces:

  • The class. It can be a fully qualified type name or in case the class resides in any of java.lang, java.util or java.io packages it can be a short (simple) name.
  • The method name.
  • Parameter types. The types are treated in the same way as the class above.
  • Arity. It denotes how many elements from ParameterStack should be popped.

NOTE: The parameter types must be identical to those of the constructor declaration.

Examples

  • Get the Integer value of a String.
." 12 ". ,< Integer/valueOf(String)/1 >,
  • Method with a variadic argument
." world ". ." Hello ". ." ,  ". ,< String/join(CharSequence, CharSequence...)/3 >,