MathJ

Math using object perspective. Instead of created a specific method to define a mathematical function, MathJ offers a dynamic approach. This is a example how to use MathJ :

@Test public void
should_run_integration_test() {
    Context context = new MapContext();
    MathJ mathJ = new MathJ(context);

    Equation eq_2x_add_2y = asEq(asConst(2)).multiply(asVar("x"))
                                                            .add(
                            asEq(asConst(2)).multiply(asVar("y"))
                            );
    // By default x=0, y=0
    mathJ.addContext("x")
         .addContext("y");

    // 2(0) + 2(0) = 0
    assertEquals(0, mathJ.apply(eq_2x_add_2y).value());

    // 2(3) + 2(4) = 14
    mathJ.setContext("x", asConst(3))
            .setContext("y", asConst(4));
    assertEquals(14, mathJ.apply(eq_2x_add_2y).value());

}

MathJ is limited to integer type operation, it can handles : add, minus, multiply and divide operation.

MathJ provides a simple String parser to interpret a mathematical expression to a java object

@Test public void // 2 / ((1 + 1) + 2
should_2_divide_$$1_plus_1££_plus_2() throws SyntaxException, ValidationReaderException {
    Function func =reader.read("2 / ((1 + 1)) + 2");

    assertEquals(3, value(func));
}

...

private int value(Function func) {
    return mathJ.apply(func).value();
}