convert decimal to octal value

src/main/java/com/conversions/DecimalToOctal.java

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+package src.main.java.com.conversions;
+
+import java.math.BigInteger;
+
+public class DecimalToOctal {
+    private static final char octalChars[] = {'0','1','2','3','4','5','6','7'};
+    private static final BigInteger valueOctal = new BigInteger("8");
+
+    /**
+     * This method converts and decimal number to a octal number
+     * @param decimalStr
+     * @return octal number
+     */
+    public String decimalToOctal(String decimalStr){
+        BigInteger decimal = new BigInteger(decimalStr);
+
+        int rem;
+        String octal = "";
+        while(decimal.compareTo(BigInteger.ZERO) > 0) {
+            rem = decimal.mod(valueOctal).intValueExact();
+            octal = octalChars[rem] + octal;
+            decimal = decimal.divide(valueOctal);
+        }
+        return octal;
+    }
+}

src/test/java/com/conversions/DecimalToOctalTest.java

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+package src.test.java.com.conversions;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class DecimalToOctalTest {
+    @Test
+    public void testDecimalToOctalTest() {
+        DecimalToOctal decimalToOctal = new DecimalToOctal();
+        Assert.assertEquals("Incorrect Conversion", "41", decimalToOctal.decimalToOctal("33"));
+        Assert.assertEquals("Incorrect Conversion", "5512", decimalToOctal.decimalToOctal("2890"));
+        Assert.assertEquals("Incorrect Conversion", "12525252525252525252525241", decimalToOctal.decimalToOctal("50371909150609548946081"));
+        Assert.assertEquals("Incorrect Conversion", "13", decimalToOctal.decimalToOctal("11"));
+        Assert.assertEquals("Incorrect Conversion", "46703754", decimalToOctal.decimalToOctal("10192876"));
+    }
+}