ActiveJava

Copyright Tristan Aubrey-Jones May 2008.

Abstract: A project investigating and developing an implicitly concurrent programming language, based on a metaphor taken from the physical world is reported. Uses a programming paradigm where programs consist of systems of autonomous agents, or active objects which communicate via message passing. A language enhancing Java with actors and linear types is presented. Example programs are written, compiled, and executed to evaluate the usefulness of the language. The language found to provide a familiar notation for implicit parallelism, and a compelling new model for concurrency, combining the performance of shared variables with the elegance of message passing.

Introductory Slides (PDF), Report (PDF),
ActiveJava compiler prototype (ajavac), ActiveJava runtime library (ajava_lang).

Examples: 

calc - pocket calculator actor program
dining - dining philosophers actor program (never deadlocks)
sort - parallel quicksort implementation ("SortBenchmark" sorts 10,000 random integers using actors, java threads, and sequentially and compares)
To compile examples use:
compile.bat ./calc
compile.bat ./sort
compile.bat ./dining
To run examples use:
run ./calc Main
run ./dining Main
run ./dining Main fast
run ./sort Main
run ./sort SortingBenchmark

NumberBox.ajava

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import javax.swing.*;

public aclass NumberBox extends AComponent {

    protected JTextField textField;
    private boolean reset = false;
    private boolean donePoint = false;
   
    public final Event OnOperation = new Event();

    public NumberBox() {
        super(new JTextField(15));
        textField = (JTextField)(component);
        textField.setHorizontalAlignment(JTextField.RIGHT);
        textField.setText("0");
    }
       
    // appends a character (digit, or point)
    // to the current numeral
    public react (char c) {
        // digit
        if (Character.isDigit(c)) {
                if (reset) {
                    textField.setText("" + c);
                    reset = false;
                }
                else if (textField.getText().equals("0")) {
                    if (c != '0') textField.setText("" + c);
                } else {
                    textField.setText(textField.getText() + "" + c);
                }
        }
        // decimal point
        else if (c == '.' && !donePoint) {
            textField.setText(textField.getText() + '.');
            donePoint = true;
        }
    }
   
    // injects the current operand into the operation
    // and forwards it to the ALU
    public react (Calculator.Operation op) {    
        // pass to ALU
        op.operand = Double.parseDouble(textField.getText());
        OnOperation <-- op;
    }
   
    // sets the value, resulting from an ALU
    // operation
    public react (double v) {
        textField.setText(Double.toString(v));
        reset = true;
        donePoint = false;
    }
}