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Error.dumpStack() - prints stack trace of the current thread - just like java.lang.Thread.dumpStack()

Code Block

title	Error extensions

function func() {
    throw new Error()
}

function f() {
    func()
}

try {
    f()
} catch (e) {
    print(e.stack)
    print(e.lineNumber)
    print(e.columnNumber)
    print(e.fileName)
}

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Code Block

title	Java.extend examples

var ArrayList = Java.type("java.util.ArrayList")
var ArrayListExtender = Java.extend(ArrayList)
var printSizeInvokedArrayList = new ArrayListExtender() {
    size: function() { print("size invoked!"); }
}

var printAddInvokedArrayList = new ArrayListExtender() {
    add: function(x, y) {
      if(typeof(y) === "undefined") {
          print("add(e) invoked!");
      } else {
          print("add(i, e) invoked!");
      }
    }
}

Anchor

	Java_extend_javac_example
	Java_extend_javac_example

Code Block

title	Java.extend - larger example

#// Usage: jjs javafoovars.js -- <directory>

// This example demonstrates Java subclassing by Java.extend
// and javac Compiler and Tree API. This example counts number
// of variables called "foo" in the given java source files!
if (arguments.length == 0) {
    print("Usage: jjs javafoovars.js -- <directory>");
    exit(1);
}

// Java types used
var File = Java.type("java.io.File");
var Files = Java.type("java.nio.file.Files");
var FileVisitOption = Java.type("java.nio.file.FileVisitOption");
var StringArray = Java.type("java.lang.String[]");
var ToolProvider = Java.type("javax.tools.ToolProvider");
var Tree = Java.type("com.sun.source.tree.Tree");
var TreeScanner = Java.type("com.sun.source.util.TreeScanner");
var VariableTree = Java.type("com.sun.source.tree.VariableTree");

// count "foo"-s in the given .java files
function countFoo() {
    // get the system compiler tool
    var compiler = ToolProvider.systemJavaCompiler;
    // get standard file manager
    var fileMgr = compiler.getStandardFileManager(null, null, null);
    // Using Java.to convert script array (arguments) to a Java String[]
    var compUnits = fileMgr.getJavaFileObjects(
        Java.to(arguments, StringArray));
    // create a new compilation task
    var task = compiler.getTask(null, fileMgr, null, null, null, compUnits);
    // subclass SimpleTreeVisitor - to count variables called "foo"
    var FooCounterVisitor = Java.extend(TreeScanner);
    var fooCount = 0;

    var visitor = new FooCounterVisitor() {
        visitVariable: function (node, p) {
            if (node.name.toString() == "foo") {
                fooCount++;
            }
        }
    }

    for each (var cu in task.parse()) {
        cu.accept(visitor, null);
    }
    return fooCount;
}

// for each ".java" file in directory (recursively) count "foo".
function main(dir) {
    var totalCount = 0;
    Files.walk(dir.toPath(), FileVisitOption.FOLLOW_LINKS).
      forEach(function(p) {
        var name = p.toFile().absolutePath;
        if (name.endsWith(".java")) {
            var count = 0;
            try {
                count = countFoo(p.toFile().getAbsolutePath());
            } catch (e) {
                print(e);
            }
            if (count != 0) {
                print(name + ": " + count);
            }
            totalCount += count;
        }
      });
    print("Total foo count: " + totalCount);
}

main(new File(arguments[0]));

Java.from function

Given a Java array or Collection, this function returns a JavaScript array with a shallow copy of its contents. Note that in most cases, you can use Java arrays and lists natively in Nashorn; in cases where for some reason you need to have an actual JavaScript native array (e.g. to work with the array comprehensions functions), you will want to use this method. Example:

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New Version 50

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