JavaCro'14 - JCalc Calculations in Java with open source API – Davor Sauer

• 1. Calculations in Java with open source APICalculations in Java with open source APICalculations in Java with open source APICalculations in Java with open source API Author: Davor Sauer www.jdice.org

2. Content Calculations in Java- basics Calculations in Java with JCalc Comparison of complex calculation with plain Java and Features Questions of complex calculation with plain Java and JCalc 3. Calculations in Java- Example: Simple calculation: If you pay $2.00 for a beer that costs $1.10, how much changes do you get? System.out.println(2.00 - 1.10); Answers: a) b) c) d) gDecimal payment = new BigDecimal(2.00); Answers:gDecimal payment = new BigDecimal(2.00); gDecimal cost = new BigDecimal(1.10); ystem.out.println(payment.subtract(cost)); Answers: a) b) c) d) => 0.89999999991118215802998747... gDecimal payment = new BigDecimal("2.00"); gDecimal cost = new BigDecimal("1.10"); ystem.out.println(payment.subtract(cost)); Answers: a) b) c) d) - basics Simple calculation: If you pay $2.00 for a beer that costs $1.10, Answers: .9 .90 0.899999999999 None of the above Answers:Answers: .9 .90 0.899999999999 None of the above => 0.89999999991118215802998747... Answers: .9 0.90 0.899999999999 None of the above 4. ava + JCalc ...more sugar? 5. Calculations in Java- Example: Simple calculation: If you pay $2.00 for a beer that costs $1.10, how much changes do you get? System.out.println(Calculator.builder().val(2.00).sub(1.10). m p = new Num(2.00); m c = new Num(1.10);m c = new Num(1.10); tem.out.println(Calculator.builder().val(p).sub(c).calculate m p = new Num("2.00"); m c = new Num("1.10"); tem.out.println(Calculator.builder().val(p).sub(c).setStripTrailingZeros tem.out.println(Calculator.builder("2.00 - 1.10").setStripTrailingZeros - basics Simple calculation: If you pay $2.00 for a beer that costs $1.10, ().val(2.00).sub(1.10).calculate()); Answers: a) 0.9 b) .90 c) 0.899999999999 d) None of the above 0.899999999999 d) None of the above calculate()); Answers: a) .9 b) .90 c) 0.899999999999 d) None of the above setStripTrailingZeros(false).calculate()); setStripTrailingZeros(false).calculate()); Answers: a) .9 b) 0.90 c) 0.89999999 d) None of th 0.9 0.89999999991118215802998747... 6. Complex example Calculate fixed monthly payment for a fixed rate mortgage by Java ecimal interestRate = new BigDecimal("6.5"); // fixed yearly interest rate in % ecimal P = new BigDecimal(200000); ecimal paymentYears = new BigDecimal(30); onthly interest rate => 6.5 / 12 / 100 = 0.0054166667 ecimal r = interestRate.divide(new BigDecimal(12), 10, BigDecimal.ROUND_HALF_UP).divide(new umerator > 0.005416666 * 200000 = 1083.3333400000 ecimal numerator = r.multiply(P); enominatorenominator .add(new BigDecimal(1)); // => 1.0054166667 ecimal pow = new BigDecimal(30 * 12); // N = 30 * 12 > 1.005416666 ^ (-30 * 12) ===> 1 / 1.005416666 ^ (30 * 12) ecimal one = BigDecimal.ONE; ecimal r_pow = r.pow(pow.intValue()); // => 1.0054166667 ^ 360 = 6.99179805731691416804.... w = one.divide(r_pow, 10, BigDecimal.ROUND_HALF_UP); // => 1 / 6.991798.. = 0.1430247258 > 1 - 0.1430247258 = 0.8569752742 ecimal denominator = new BigDecimal(1); minator = denominator.subtract(r_pow); > 1083.3333400000 / 0.8569752742 = 1264.1360522464 ecimal c = numerator.divide(denominator, 10, BigDecimal.ROUND_HALF_UP); .setScale(2, BigDecimal.ROUND_HALF_UP); em.out.println("c = " + c); Calculate fixed monthly payment for a fixed rate mortgage by Java ).divide(new BigDecimal(100), 10, BigDecimal.ROUND_HALF_UP); // => 1.0054166667 ^ 360 = 6.99179805731691416804.... // => 1 / 6.991798.. = 0.1430247258 Line of code: 15 7. Complex example Calculate fixed monthly payment for a fixed rate mortgage by Java m interestRate = new Num(6.5); // fixed yearly interest rate in % m P = new Num(200000); m paymentYears = new Num(30); monthly interest rate : r = 6.5 / 100 / 12 m r = Calculator.builder().openBracket().val(interestRate).div(100).closeBracket().div(12).calculate(); = 30 * 12 * -1 m N = Calculator.builder().val(paymentYears).mul(12).mul(-1).calculate(); = (r * P) / (1 / (1 + r)^N ulator c = new Calculator() = (r * P) / (1 / (1 + r)^N ulator c = new Calculator() .openBracket() .val(r).mul(P) .closeBracket() // numerator .div() // --------------- .openBracket() // denumerator .val(1).sub().openBracket().val(1).add(r).closeBracket .closeBracket(); m result = c.calculate().setScale(2); em.out.println("c = " + result); Line Calculate fixed monthly payment for a fixed rate mortgage by Java ().div(12).calculate(); closeBracket().pow(N) Line of code: 8 8. Complex example Calculate fixed monthly payment for a fixed rate mortgage by Java m interestRate = new Num("A", 6.5); m P = new Num("B", 200000); m paymentYears = new Num("C", -30); ulator c = Calculator.builder("((A / 100 / 12) * B) / (1 - ((1 + (A / 100 / 12)) ^ (C * 12)))", m result = c.calculate(); em.out.println("c = " + result.setScale(2)); Line Calculate fixed monthly payment for a fixed rate mortgage by Java ((1 + (A / 100 / 12)) ^ (C * 12)))", interestRate, P, paymentYears); Line of code: 6 9. Feature: Show calculation Num interestRate = new Num("A", 6.5); Num P = new Num("B", 200000); Num paymentYears = new Num("C", -30); Calculator c = Calculator.builder("((A / 100 / 12) * B) / (1 - ((1 + (A / 100 / 12)) ^ (C * 12)))", c.setScale(10); Num result = c.calculate(true, false); // track calculation steps, track details for(String step : c.getCalculationSteps()) System.out.println(step); System.out.println("c = " + result.setScale(2)); Output: 6.5 / 100 = 0.065 0.065/ 12 = 0.0054166667 0.0054166667 * 200000 6.5 / 100 = 0.065 0.065/ 12 = 0.0054166667 1 + 0.0054166667 -30 * 12 = -360 1.0054166667 ^ -360 1 - 0.1430247258 1083.33334/ 0.8569752742 c = 1264.14 calculation steps ((1 + (A / 100 / 12)) ^ (C * 12)))", interestRate, P, paymentYears); = 0.065 = 0.0054166667 * 200000 = 1083.33334 = 0.065 = 0.0054166667 + 0.0054166667 = 1.0054166667 360 = 0.1430247258 = 0.8569752742 / 0.8569752742 = 1264.1360522464 10. Feature: Modularity Calculator calc = new Calculator(); calc.register(QuestionOperator.class); // register custom operator '?' calc.register(SumFunction.class); // register custom function 'sum' calc.expression("2 ? 2 + 5 - 1 + sum(1,2,3,4)"); @SingletonComponent@SingletonComponent public class QuestionOperator implements Operator { .... // module for ? operator .... } @SingletonComponent public class SumFunction implements Function { .... // module for function sum .... } // register custom operator '?' register custom function 'sum' implements Operator { 11. Feature: Default configuration roundingMode=HALF_UP scale=2 stripTrailingZeros=true decimalSeparator.out='.' decimalSeparator.in='.' numconverter[0]=org.jdice.calc.test.NumTest$CustomObject > org.jdice.calc.test.NumTest$CustomObjectNumConverter Configure default properties with 'jcalc.properties' file in class path numconverter[0]=org.jdice.calc.test.NumTest$CustomObject > org.jdice.calc.test.NumTest$CustomObjectNumConverter operator[0]=org.jdice.calc.test.CustomOperatorFunctionTest$QuestionOperator function[0]=org.jdice.calc.test.CustomOperatorFunctionTest$SumFunction configuration org.jdice.calc.test.NumTest$CustomObjectNumConverter ' file in class path org.jdice.calc.test.NumTest$CustomObjectNumConverter org.jdice.calc.test.CustomOperatorFunctionTest$QuestionOperator org.jdice.calc.test.CustomOperatorFunctionTest$SumFunction 12. ions, ideas, suggestions Project page: www.jdice.org