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Merge remote-tracking branch 'eugenp/master'
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‎algorithms/README.md

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- [Calculate the Distance Between Two Points in Java](https://www.baeldung.com/java-distance-between-two-points)
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- [Find the Intersection of Two Lines in Java](https://www.baeldung.com/java-intersection-of-two-lines)
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- [Check If a String Contains All The Letters of The Alphabet](https://www.baeldung.com/java-string-contains-all-letters)
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- [Round Up to the Nearest Hundred](https://www.baeldung.com/java-round-up-nearest-hundred)
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- [Merge Sort in Java](https://www.baeldung.com/java-merge-sort)
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- [Calculate Percentage in Java](https://www.baeldung.com/java-calculate-percentage)

‎algorithms/pom.xml

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<artifactId>commons-math3</artifactId>
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<version>${commons-math3.version}</version>
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</dependency>
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<dependency>
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<groupId>commons-codec</groupId>
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<artifactId>commons-codec</artifactId>
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<version>${commons-codec.version}</version>
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</dependency>
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<dependency>
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<groupId>org.projectlombok</groupId>
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<artifactId>lombok</artifactId>
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<io.jenetics.version>3.7.0</io.jenetics.version>
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<org.jgrapht.core.version>1.0.1</org.jgrapht.core.version>
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<org.assertj.core.version>3.9.0</org.assertj.core.version>
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<commons-codec.version>1.11</commons-codec.version>
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</properties>
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</project>

‎algorithms/src/main/java/com/baeldung/algorithms/conversion/HexStringConverter.java

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package com.baeldung.algorithms.conversion;
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import java.math.BigInteger;
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import javax.xml.bind.DatatypeConverter;
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import org.apache.commons.codec.DecoderException;
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import org.apache.commons.codec.binary.Hex;
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import com.google.common.io.BaseEncoding;
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public class HexStringConverter {
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/**
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* Create a byte Array from String of hexadecimal digits using Character conversion
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* @param hexString - Hexadecimal digits as String
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* @return Desired byte Array
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*/
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public byte[] decodeHexString(String hexString) {
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if (hexString.length() % 2 == 1) {
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throw new IllegalArgumentException("Invalid hexadecimal String supplied.");
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}
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byte[] bytes = new byte[hexString.length() / 2];
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for (int i = 0; i < hexString.length(); i += 2) {
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bytes[i / 2] = hexToByte(hexString.substring(i, i + 2));
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}
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return bytes;
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}
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/**
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* Create a String of hexadecimal digits from a byte Array using Character conversion
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* @param byteArray - The byte Array
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* @return Desired String of hexadecimal digits in lower case
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*/
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public String encodeHexString(byte[] byteArray) {
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StringBuffer hexStringBuffer = new StringBuffer();
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for (int i = 0; i < byteArray.length; i++) {
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hexStringBuffer.append(byteToHex(byteArray[i]));
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}
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return hexStringBuffer.toString();
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}
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public String byteToHex(byte num) {
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char[] hexDigits = new char[2];
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hexDigits[0] = Character.forDigit((num >> 4) & 0xF, 16);
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hexDigits[1] = Character.forDigit((num & 0xF), 16);
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return new String(hexDigits);
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}
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public byte hexToByte(String hexString) {
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int firstDigit = toDigit(hexString.charAt(0));
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int secondDigit = toDigit(hexString.charAt(1));
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return (byte) ((firstDigit << 4) + secondDigit);
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}
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private int toDigit(char hexChar) {
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int digit = Character.digit(hexChar, 16);
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if(digit == -1) {
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throw new IllegalArgumentException("Invalid Hexadecimal Character: "+ hexChar);
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}
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return digit;
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}
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public String encodeUsingBigIntegerToString(byte[] bytes) {
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BigInteger bigInteger = new BigInteger(1, bytes);
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return bigInteger.toString(16);
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}
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public String encodeUsingBigIntegerStringFormat(byte[] bytes) {
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BigInteger bigInteger = new BigInteger(1, bytes);
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return String.format("%0" + (bytes.length << 1) + "x", bigInteger);
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}
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public byte[] decodeUsingBigInteger(String hexString) {
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byte[] byteArray = new BigInteger(hexString, 16).toByteArray();
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if (byteArray[0] == 0) {
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byte[] output = new byte[byteArray.length - 1];
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System.arraycopy(byteArray, 1, output, 0, output.length);
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return output;
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}
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return byteArray;
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}
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public String encodeUsingDataTypeConverter(byte[] bytes) {
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return DatatypeConverter.printHexBinary(bytes);
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}
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public byte[] decodeUsingDataTypeConverter(String hexString) {
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return DatatypeConverter.parseHexBinary(hexString);
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}
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public String encodeUsingApacheCommons(byte[] bytes) throws DecoderException {
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return Hex.encodeHexString(bytes);
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}
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public byte[] decodeUsingApacheCommons(String hexString) throws DecoderException {
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return Hex.decodeHex(hexString);
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}
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public String encodeUsingGuava(byte[] bytes) {
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return BaseEncoding.base16()
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.encode(bytes);
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}
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public byte[] decodeUsingGuava(String hexString) {
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return BaseEncoding.base16()
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.decode(hexString.toUpperCase());
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}
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}

‎algorithms/src/test/java/com/baeldung/algorithms/conversion/ByteArrayConverterUnitTest.java

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package com.baeldung.algorithms.conversion;
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import static org.junit.Assert.assertArrayEquals;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertThat;
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import org.apache.commons.codec.DecoderException;
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import org.hamcrest.text.IsEqualIgnoringCase;
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import org.junit.Before;
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import org.junit.Test;
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import com.baeldung.algorithms.conversion.HexStringConverter;
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public class ByteArrayConverterUnitTest {
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private HexStringConverter hexStringConverter;
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@Before
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public void setup() {
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hexStringConverter = new HexStringConverter();
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}
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@Test
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public void shouldEncodeByteArrayToHexStringUsingBigIntegerToString() {
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byte[] bytes = getSampleBytes();
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String hexString = getSampleHexString();
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if(hexString.charAt(0) == '0') {
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hexString = hexString.substring(1);
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}
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String output = hexStringConverter.encodeUsingBigIntegerToString(bytes);
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assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
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}
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@Test
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public void shouldEncodeByteArrayToHexStringUsingBigIntegerStringFormat() {
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byte[] bytes = getSampleBytes();
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String hexString = getSampleHexString();
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String output = hexStringConverter.encodeUsingBigIntegerStringFormat(bytes);
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assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
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}
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@Test
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public void shouldDecodeHexStringToByteArrayUsingBigInteger() {
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byte[] bytes = getSampleBytes();
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String hexString = getSampleHexString();
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byte[] output = hexStringConverter.decodeUsingBigInteger(hexString);
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assertArrayEquals(bytes, output);
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}
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@Test
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public void shouldEncodeByteArrayToHexStringUsingCharacterConversion() {
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byte[] bytes = getSampleBytes();
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String hexString = getSampleHexString();
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String output = hexStringConverter.encodeHexString(bytes);
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assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
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}
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@Test
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public void shouldDecodeHexStringToByteArrayUsingCharacterConversion() {
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byte[] bytes = getSampleBytes();
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String hexString = getSampleHexString();
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byte[] output = hexStringConverter.decodeHexString(hexString);
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assertArrayEquals(bytes, output);
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}
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@Test(expected=IllegalArgumentException.class)
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public void shouldDecodeHexToByteWithInvalidHexCharacter() {
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hexStringConverter.hexToByte("fg");
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}
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@Test
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public void shouldEncodeByteArrayToHexStringDataTypeConverter() {
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byte[] bytes = getSampleBytes();
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String hexString = getSampleHexString();
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String output = hexStringConverter.encodeUsingDataTypeConverter(bytes);
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assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
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}
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@Test
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public void shouldDecodeHexStringToByteArrayUsingDataTypeConverter() {
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byte[] bytes = getSampleBytes();
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String hexString = getSampleHexString();
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byte[] output = hexStringConverter.decodeUsingDataTypeConverter(hexString);
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assertArrayEquals(bytes, output);
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}
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@Test
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public void shouldEncodeByteArrayToHexStringUsingGuava() {
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byte[] bytes = getSampleBytes();
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String hexString = getSampleHexString();
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String output = hexStringConverter.encodeUsingGuava(bytes);
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assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
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}
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@Test
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public void shouldDecodeHexStringToByteArrayUsingGuava() {
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byte[] bytes = getSampleBytes();
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String hexString = getSampleHexString();
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byte[] output = hexStringConverter.decodeUsingGuava(hexString);
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assertArrayEquals(bytes, output);
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}
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@Test
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public void shouldEncodeByteArrayToHexStringUsingApacheCommons() throws DecoderException {
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byte[] bytes = getSampleBytes();
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String hexString = getSampleHexString();
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String output = hexStringConverter.encodeUsingApacheCommons(bytes);
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assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
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}
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@Test
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public void shouldDecodeHexStringToByteArrayUsingApacheCommons() throws DecoderException {
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byte[] bytes = getSampleBytes();
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String hexString = getSampleHexString();
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byte[] output = hexStringConverter.decodeUsingApacheCommons(hexString);
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assertArrayEquals(bytes, output);
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}
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private String getSampleHexString() {
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return "0af50c0e2d10";
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}
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private byte[] getSampleBytes() {
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return new byte[] { 10, -11, 12, 14, 45, 16 };
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}
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}

‎aws/README.md

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- [Integration Testing with a Local DynamoDB Instance](http://www.baeldung.com/dynamodb-local-integration-tests)
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- [Using the JetS3t Java Client With Amazon S3](http://www.baeldung.com/jets3t-amazon-s3)
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- [Managing Amazon SQS Queues in Java](http://www.baeldung.com/aws-queues-java)
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- [Guide to AWS Aurora RDS with Java](https://www.baeldung.com/aws-aurora-rds-java)

‎core-java-8/findItemsBasedOnValues/.gitignore

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/bin/

‎core-java-8/findItemsBasedOnValues/src/findItems/FindItemsBasedOnValues.java

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package findItems;
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import static org.junit.Assert.assertEquals;
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import java.text.ParseException;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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import java.util.stream.Collectors;
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import org.junit.Test;
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public class FindItemsBasedOnValues {
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List<Employee> EmplList = new ArrayList<Employee>();
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List<Department> deptList = new ArrayList<Department>();
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public static void main(String[] args) throws ParseException {
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FindItemsBasedOnValues findItems = new FindItemsBasedOnValues();
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findItems.givenDepartmentList_thenEmployeeListIsFilteredCorrectly();
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}
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@Test
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public void givenDepartmentList_thenEmployeeListIsFilteredCorrectly() {
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Integer expectedId = 1002;
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populate(EmplList, deptList);
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List<Employee> filteredList = EmplList.stream()
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.filter(empl -> deptList.stream()
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.anyMatch(dept -> dept.getDepartment()
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.equals("sales") && empl.getEmployeeId()
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.equals(dept.getEmployeeId())))
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.collect(Collectors.toList());
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assertEquals(expectedId, filteredList.get(0)
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.getEmployeeId());
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}
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private void populate(List<Employee> EmplList, List<Department> deptList) {
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Employee employee1 = new Employee(1001, "empl1");
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Employee employee2 = new Employee(1002, "empl2");
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Employee employee3 = new Employee(1003, "empl3");
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Collections.addAll(EmplList, employee1, employee2, employee3);
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Department department1 = new Department(1002, "sales");
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Department department2 = new Department(1003, "marketing");
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Department department3 = new Department(1004, "sales");
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Collections.addAll(deptList, department1, department2, department3);
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}
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}
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class Employee {
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Integer employeeId;
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String employeeName;
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public Employee(Integer employeeId, String employeeName) {
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super();
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this.employeeId = employeeId;
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this.employeeName = employeeName;
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}
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public Integer getEmployeeId() {
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return employeeId;
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}
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public String getEmployeeName() {
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return employeeName;
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}
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}
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class Department {
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Integer employeeId;
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String department;
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public Department(Integer employeeId, String department) {
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super();
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this.employeeId = employeeId;
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this.department = department;
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}
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public Integer getEmployeeId() {
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return employeeId;
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}
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public String getDepartment() {
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return department;
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}
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}

‎core-java-9/README.md

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- [Iterate Through a Range of Dates in Java](https://www.baeldung.com/java-iterate-date-range)
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- [Initialize a HashMap in Java](https://www.baeldung.com/java-initialize-hashmap)
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- [Java 9 Platform Logging API](https://www.baeldung.com/java-9-logging-api)
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- [Guide to java.lang.Process API](https://www.baeldung.com/java-process-api)

‎core-java-collections/README.md

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- [Performance of contains() in a HashSet vs ArrayList](https://www.baeldung.com/java-hashset-arraylist-contains-performance)
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- [Get the Key for a Value from a Java Map](https://www.baeldung.com/java-map-key-from-value)
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- [Time Complexity of Java Collections](https://www.baeldung.com/java-collections-complexity)
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- [Sort a HashMap in Java](https://www.baeldung.com/java-hashmap-sort)
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- [Finding the Highest Value in a Java Map](https://www.baeldung.com/java-find-map-max)
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- [Operating on and Removing an Item from Stream](https://www.baeldung.com/java-use-remove-item-stream)

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