gistfile1.txt

[davinci]$ cat Hello.java 
import java.dyn.*;

public class Hello {
    public static void main(String... av) throws Throwable {
        if (av.length == 0)  av = new String[] { "world" };
        greeter(av[0] + " (from a statically linked call site)");
        for (String whom : av) {
            greeter.<void>invokeExact(whom);  // strongly typed direct call
            // previous line generates invokevirtual MethodHandle.invokeExact(String)void
            Object x = whom;
            InvokeDynamic.hail(x);               // weakly typed invokedynamic
            // previous line generates invokedynamic hail(Object)Object
        }
    }

    static void greeter(String x) { System.out.println("Hello, "+x); }
    // intentionally pun between the method and its reified handle:
    static MethodHandle greeter
            = MethodHandles.lookup().findStatic(Hello.class, "greeter",
                           MethodType.methodType(void.class, String.class));

    // Set up a class-local bootstrap method.
    static { Linkage.registerBootstrapMethod("bootstrapDynamic"); }
    private static CallSite bootstrapDynamic(Class caller, String name, MethodType type) {
        assert(type.parameterCount() == 1 && name.equals("hail"));  // in lieu of MOP
        System.out.println("set target to adapt "+greeter);
        return new CallSite(greeter.asType(type));
    }
}

// String x = InvokeDynamic.<@BootstrapMethod(MyCallSite.class) String>greet();
// InvokeDynamic.<@BootstrapMethod(value=MyLinker.class, name="myBootstrap") void>greet();
[davinci]$ 
[davinci]$ java -version
openjdk version "1.7.0-internal-fastdebug"
OpenJDK Runtime Environment (build 1.7.0-internal-fastdebug-stephen_2010_07_30_11_56-b00)
OpenJDK Server VM (build 19.0-b03-fastdebug, mixed mode)
[davinci]$ 
[davinci]$ javac Hello.java 
Hello.java:11: warning: InvokeDynamic calls must be in scope of a @BootstrapMethod annotation (registerBootstrapMethod is deprecated)
            InvokeDynamic.hail(x);               // weakly typed invokedynamic
                              ^
Note: Hello.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
1 warning
[davinci]$ 
[davinci]$ java Hello
Exception in thread "main" java.lang.ClassFormatError: invokedynamic instructions not enabled in this JVM in method Hello.main([Ljava/lang/String;)V
	at java.lang.Class.getDeclaredMethods0(Native Method)
	at java.lang.Class.privateGetDeclaredMethods(Class.java:2440)
	at java.lang.Class.getMethod0(Class.java:2683)
	at java.lang.Class.getMethod(Class.java:1618)
	at sun.launcher.LauncherHelper.signatureDiagnostic(LauncherHelper.java:210)
	at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:202)

missing_bit='-XX:+UnlockExperimentalVMOptions -XX:+EnableInvokeDynamic'
--------
    $JAVA7X_HOME/bin/javac Hello.java
Note: Hello.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
--------
    $JAVA7X_HOME/bin/java Hello
Exception in thread "main" java.lang.ClassFormatError: invokedynamic instructions not enabled in this JVM in method Hello.main([Ljava/lang/String;)V
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2440)
    at java.lang.Class.getMethod0(Class.java:2683)
    at java.lang.Class.getMethod(Class.java:1618)
    at sun.launcher.LauncherHelper.signatureDiagnostic(LauncherHelper.java:210)
    at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:202)
--------
    $JAVA7X_HOME/bin/java -XX:+UnlockExperimentalVMOptions -XX:+EnableInvokeDynamic Hello
Duration invokedynamic: 146
Duration reflection: 1490
--------