// This macro demonstrates how macros can call Java
// classes. It uses the call() function added in ImageJ 1.37c,
// which was contributed by Johannes Schindelin. The call
// function calls a public static method, passing an arbitrary 
// number of string arguments, returning a string. If a Java
// method returns a value that is not a string (e.g., boolean,
// int, long, etc) then that value is converted to a string.

    requires("1.37c");
    print("ImageJ version:", call("ij.IJ.getVersion")); // same as getVersion()
    print("java.version:", call("java.lang.System.getProperty", "java.version"));
    print("user.home:", call("java.lang.System.getProperty", "user.home"));
    print("user.dir:", call("java.lang.System.getProperty", "user.dir"));
    print("Images URL:", call("ij.Prefs.getImagesURL"));
    print("Plugins path:", call("ij.Menus.getPlugInsPath"));

    // V1.37e or later is required to call methods that do not return a string.
    // Note that non-string returned values are converted to strings.
    if (getVersion>="1.37e") {
        print("Time:", call("java.lang.System.currentTimeMillis")); // returns a string
        print("Free memory:", call("ij.IJ.freeMemory")); // returns a string
        print("Max memory:", parseInt(call("ij.IJ.maxMemory"))/(1024*1024)+"MB");
        print("Alt key down:", call("ij.IJ.altKeyDown")); // returns "true" or "false"
        print("Is Macintosh:", call("ij.IJ.isMacintosh")); // returns "true" or "false"
        call("java.lang.System.gc"); // run garbage collector
        call("ij.IJ.beep");
        prefsString = call("ij.Prefs.get", "demo.string", "Text for preferences file");
        prefsString = getString("Text:", prefsString);
        call("ij.Prefs.set", "demo.string", prefsString);
   } else
       print("V1.37e or later is required to call methods that do not return a string");

    // Call three methods in CallDemo.class, located in the
    // plugins folder. The first method that has no arguments,
    // the second has one and a third has two.
    call("CallDemo.method0");
    call("CallDemo.method1", "arg1");
    call("CallDemo.method2", "arg1", "arg2");

// This is what the methods in CallDemo.java look like:
//
//     public static String method0() {
//         return "method0";
//     }
//
//     public static String method1(String arg1) {
//         return "method1"+"("+arg1+")";
//     }
//
//     public static String method2(String arg1, String arg2) {
//         return "method2"+"("+arg1+", "+arg2+")";
//     }
//
// The source for the CallDemo class is at
// <http://rsb.info.nih.gov/ij/download/docs/CallDemo.java>
// Use ImageJ's Plugins>Compile and Run command to compile it.