Merge pull request #16337 from yadavan88/complex-number-ops

Complex number operations

core-java-modules/core-java-numbers-7/src/main/java/com/baeldung/complexnumbers/ComplexNumber.java

@@ -0,0 +1,57 @@
+package com.baeldung.complexnumbers;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public record ComplexNumber(double real, double imaginary) {
+
+    public static ComplexNumber fromString(String complexNumberStr) {
+
+        Pattern pattern = Pattern.compile("(-?\\d*\\.?\\d+)?(?:([+-]?\\d*\\.?\\d+)i)?");
+        Matcher matcher = pattern.matcher(complexNumberStr.replaceAll("\\s", ""));
+
+        if (matcher.matches()) {
+            // Extract real and imaginary parts
+            String realPartStr = matcher.group(1);
+            String imaginaryPartStr = matcher.group(2);
+
+            // Parse real part (if present)
+            double real = (realPartStr != null) ? Double.parseDouble(realPartStr) : 0;
+
+            // Parse imaginary part (if present)
+            double imaginary = (imaginaryPartStr != null) ? Double.parseDouble(imaginaryPartStr) : 0;
+            return new ComplexNumber(real, imaginary);
+        } else {
+            throw new IllegalArgumentException("Invalid complex number format(" + complexNumberStr + "), supported format is `a+bi`");
+        }
+    }
+
+    public String toString() {
+        return real + "+" + imaginary + "i";
+    }
+
+    public ComplexNumber add(ComplexNumber that) {
+        return new ComplexNumber(real + that.real, imaginary + that.imaginary);
+    }
+
+    public ComplexNumber multiply(ComplexNumber that) {
+        double newReal = this.real * that.real - this.imaginary * that.imaginary;
+        double newImaginary = this.real * that.imaginary + this.imaginary * that.real;
+        return new ComplexNumber(newReal, newImaginary);
+    }
+
+    public ComplexNumber subtract(ComplexNumber that) {
+        return new ComplexNumber(real - that.real, imaginary - that.imaginary);
+    }
+
+    public ComplexNumber divide(ComplexNumber that) {
+        if(that.real == 0 && that.imaginary == 0 ){
+            throw new ArithmeticException("Division by 0 is not allowed!");
+        }
+        double c2d2 = Math.pow(that.real, 2) + Math.pow(that.imaginary, 2);
+        double newReal = (this.real * that.real + this.imaginary * that.imaginary) / c2d2;
+        double newImaginary = (this.imaginary * that.real - this.real * that.imaginary) / c2d2;
+        return new ComplexNumber(newReal, newImaginary);
+    }
+
+}

core-java-modules/core-java-numbers-7/src/test/java/com/baeldung/complexnumbers/ComplexNumberOperationsUnitTest.java

@@ -0,0 +1,103 @@
+package com.baeldung.complexnumbers;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+public class ComplexNumberOperationsUnitTest {
+
+    @ParameterizedTest(name = "Multiplying {0} and {1}")
+    @CsvSource({
+            "3+2i, 1+7i, -11+23i",
+            "2, 4, 8",
+            "2, 4i, 8i",
+            "1+1i, 1+1i, 0+2i",
+            "  3+2i, 1 +    7i,   -11 + 23i   ",
+            "0+5i, 3+0i, 0+15i",
+            "0+0i, -2+0i, 0+0i",
+            "-3+2i, 1-7i, 11+23i",
+            "2+4i, 0, 0"
+    })
+    public void givenTwoComplexNumbers_multiplyAndGetResult(String complexStr1, String complexStr2, String expectedStr) {
+        ComplexNumber complex1 = ComplexNumber.fromString(complexStr1);
+        ComplexNumber complex2 = ComplexNumber.fromString(complexStr2);
+        ComplexNumber expected = ComplexNumber.fromString(expectedStr);
+        ComplexNumber product = complex1.multiply(complex2);
+        Assertions.assertTrue(isSame(product, expected));
+    }
+
+    @ParameterizedTest(name = "Adding {0} and {1}")
+    @CsvSource({
+            "3+2i, 1+7i, 4+9i",
+            "2, 4, 6",
+            "2, 4i, 2+4i",
+            "1+1i, 1+1i, 2+2i",
+            "  3+2i, 1 +    7i,   4 + 9i   ",
+            "0+5i, 3+0i, 3+5i",
+            "0+0i, -2+0i, -2+0i",
+            "-3+2i, 1-7i, -2-5i",
+            "2+4i, 0, 2+4i"
+    })
+    public void givenTwoComplexNumbers_addThemAndGetResult(String complexStr1, String complexStr2, String expectedStr) {
+        ComplexNumber complex1 = ComplexNumber.fromString(complexStr1);
+        ComplexNumber complex2 = ComplexNumber.fromString(complexStr2);
+        ComplexNumber expected = ComplexNumber.fromString(expectedStr);
+        ComplexNumber sum = complex1.add(complex2);
+        Assertions.assertTrue(isSame(sum, expected));
+    }
+
+    @ParameterizedTest(name = "Subtracting {0} and {1}")
+    @CsvSource({
+            "3+2i, 1+7i, 2-5i",
+            "2, 4, -2",
+            "2, 4i, 2-4i",
+            "1+1i, 1+1i, 0",
+            "  3+ 2i, 1+  7i, 2-5i",
+            "0+5i, 3+0i, -3+5i",
+            "0+0i, -2+0i, 2+0i",
+            "-3+2i, 1-7i, -4+9i",
+            "2+4i, 0, 2+4i"
+    })
+    public void givenTwoComplexNumbers_subtractAndGetResult(String complexStr1, String complexStr2, String expectedStr) {
+        ComplexNumber complex1 = ComplexNumber.fromString(complexStr1);
+        ComplexNumber complex2 = ComplexNumber.fromString(complexStr2);
+        ComplexNumber expected = ComplexNumber.fromString(expectedStr);
+        ComplexNumber sum = complex1.subtract(complex2);
+        Assertions.assertTrue(isSame(sum, expected));
+    }
+
+    @ParameterizedTest(name = "Dividing {0} and {1}")
+    @CsvSource({
+            "3+2i, 1+7i, 0.34-0.38i",
+            "2, 4, 0.5",
+            "2, 4i, 0-0.5i",
+            "1+1i, 1+1i, 1",
+            "3 +   2i, 1  +   7i, 0.34-0.38i",
+            "0+5i, 3+0i, 0+1.6666666666666667i",
+            "0+0i, -2+0i, 0+0i",
+            "-3+2i, 1-7i, -0.34-0.38i",
+            "2+4i, 1, 2+4i"
+    })
+    public void givenTwoComplexNumbers_divideThemAndGetResult(String complexStr1, String complexStr2, String expectedStr) {
+        ComplexNumber complex1 = ComplexNumber.fromString(complexStr1);
+        ComplexNumber complex2 = ComplexNumber.fromString(complexStr2);
+        ComplexNumber expected = ComplexNumber.fromString(expectedStr);
+        ComplexNumber sum = complex1.divide(complex2);
+        Assertions.assertTrue(isSame(sum, expected));
+    }
+
+    @Test
+    public void givenAComplexNumberAsZero_handleDivideByZeroScenario() {
+        ComplexNumber complex1 = new ComplexNumber(1, 1);
+        ComplexNumber zero = new ComplexNumber(0, 0);
+        Exception exception = Assertions.assertThrows(ArithmeticException.class, () -> {
+            complex1.divide(zero);
+        });
+        Assertions.assertEquals(exception.getMessage(), "Division by 0 is not allowed!");
+    }
+
+    public boolean isSame(ComplexNumber result, ComplexNumber expected) {
+        return result.real() == expected.real() && result.imaginary() == expected.imaginary();
+    }
+}