Merge pull request #8125 from eugenp/revert-8119-BAEL-3275-2

Revert "BAEL-3275: Using blocking queue for pub-sub"

libraries-apache-commons/README.md

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+## Apache Commons
+
+This module contains articles about Apache Commons libraries.
+
+### Relevant articles
+
+- [Array Processing with Apache Commons Lang 3](https://www.baeldung.com/array-processing-commons-lang)
+- [String Processing with Apache Commons Lang 3](https://www.baeldung.com/string-processing-commons-lang)
+- [Introduction to Apache Commons Math](https://www.baeldung.com/apache-commons-math)
+- [Introduction to Apache Commons Text](https://www.baeldung.com/java-apache-commons-text)
+- [A Guide to Apache Commons DbUtils](https://www.baeldung.com/apache-commons-dbutils)
+- [Apache Commons Chain](https://www.baeldung.com/apache-commons-chain)
+- [Apache Commons BeanUtils](https://www.baeldung.com/apache-commons-beanutils)
+- [Histograms with Apache Commons Frequency](https://www.baeldung.com/apache-commons-frequency)
+- [An Introduction to Apache Commons Lang 3](https://www.baeldung.com/java-commons-lang-3)

libraries-apache-commons/log4j.properties

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+log4j.rootLogger=INFO, stdout

libraries-apache-commons/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>libraries-apache-commons</artifactId>
+    <name>libraries-apache-commons</name>
+
+    <parent>
+        <artifactId>parent-modules</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-beanutils</groupId>
+            <artifactId>commons-beanutils</artifactId>
+            <version>${commons-beanutils.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-text</artifactId>
+            <version>${commons-text.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-chain</groupId>
+            <artifactId>commons-chain</artifactId>
+            <version>${commons-chain.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-dbutils</groupId>
+            <artifactId>commons-dbutils</artifactId>
+            <version>${commons.dbutils.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-math3</artifactId>
+            <version>${common-math3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-net</groupId>
+            <artifactId>commons-net</artifactId>
+            <version>${commons-net.version}</version>
+        </dependency>
+		<dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <version>${h2.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.knowm.xchart</groupId>
+            <artifactId>xchart</artifactId>
+            <version>${xchart-version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <commons-lang3.version>3.6</commons-lang3.version>
+        <commons-text.version>1.1</commons-text.version>
+        <commons-beanutils.version>1.9.3</commons-beanutils.version>
+        <commons-chain.version>1.2</commons-chain.version>
+        <assertj.version>3.6.2</assertj.version>
+        <commons.dbutils.version>1.6</commons.dbutils.version>
+        <commons-codec-version>1.10.L001</commons-codec-version>
+        <xchart-version>3.5.2</xchart-version>
+        <commons-net.version>3.6</commons-net.version>
+        <common-math3.version>3.6.1</common-math3.version>
+    </properties>
+
+</project>

libraries-apache-commons/src/main/java/com/baeldung/commons/beanutils/Course.java

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+package com.baeldung.commons.beanutils;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class Course {
+    private String name;
+    private List<String> codes;
+    private Map<String, Student> enrolledStudent = new HashMap<String, Student>();
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public List<String> getCodes() {
+        return codes;
+    }
+
+    public void setCodes(List<String> codes) {
+        this.codes = codes;
+    }
+
+    public void setEnrolledStudent(String enrolledId, Student student) {
+        enrolledStudent.put(enrolledId, student);
+    }
+
+    public Student getEnrolledStudent(String enrolledId) {
+        return enrolledStudent.get(enrolledId);
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/beanutils/CourseEntity.java

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+package com.baeldung.commons.beanutils;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class CourseEntity {
+    private String name;
+    private List<String> codes;
+    private Map<String, Student> students = new HashMap<String, Student>();
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public List<String> getCodes() {
+        return codes;
+    }
+
+    public void setCodes(List<String> codes) {
+        this.codes = codes;
+    }
+
+    public void setStudent(String id, Student student) {
+        students.put(id, student);
+    }
+
+    public Student getStudent(String enrolledId) {
+        return students.get(enrolledId);
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/beanutils/CourseService.java

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+package com.baeldung.commons.beanutils;
+
+import java.lang.reflect.InvocationTargetException;
+import java.util.List;
+
+import org.apache.commons.beanutils.BeanUtils;
+import org.apache.commons.beanutils.PropertyUtils;
+
+public class CourseService {
+
+    public static void setValues(Course course, String name, List<String> codes) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
+        // Setting the simple properties
+        PropertyUtils.setSimpleProperty(course, "name", name);
+        PropertyUtils.setSimpleProperty(course, "codes", codes);
+    }
+
+    public static void setIndexedValue(Course course, int codeIndex, String code) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
+        // Setting the indexed properties
+        PropertyUtils.setIndexedProperty(course, "codes[" + codeIndex + "]", code);
+    }
+
+    public static void setMappedValue(Course course, String enrollId, Student student) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
+        // Setting the mapped properties
+        PropertyUtils.setMappedProperty(course, "enrolledStudent(" + enrollId + ")", student);
+    }
+
+    public static String getNestedValue(Course course, String enrollId, String nestedPropertyName) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
+        return (String) PropertyUtils.getNestedProperty(course, "enrolledStudent(" + enrollId + ")." + nestedPropertyName);
+    }
+
+    public static void copyProperties(Course course, CourseEntity courseEntity) throws IllegalAccessException, InvocationTargetException {
+        BeanUtils.copyProperties(courseEntity, course);
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/beanutils/Student.java

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+package com.baeldung.commons.beanutils;
+
+public class Student {
+    private String name;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/chain/AbstractDenominationDispenser.java

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+package com.baeldung.commons.chain;
+
+import org.apache.commons.chain.Command;
+import org.apache.commons.chain.Context;
+
+import static com.baeldung.commons.chain.AtmConstants.AMOUNT_LEFT_TO_BE_WITHDRAWN;
+
+public abstract class AbstractDenominationDispenser implements Command {
+
+    @Override
+    public boolean execute(Context context) throws Exception {
+        int amountLeftToBeWithdrawn = (int) context.get(AMOUNT_LEFT_TO_BE_WITHDRAWN);
+        if (amountLeftToBeWithdrawn >= getDenominationValue()) {
+            context.put(getDenominationString(), amountLeftToBeWithdrawn / getDenominationValue());
+            context.put(AMOUNT_LEFT_TO_BE_WITHDRAWN, amountLeftToBeWithdrawn % getDenominationValue());
+        }
+        return false;
+    }
+
+    protected abstract String getDenominationString();
+
+    protected abstract int getDenominationValue();
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/chain/AtmCatalog.java

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+package com.baeldung.commons.chain;
+
+import org.apache.commons.chain.impl.CatalogBase;
+
+import static com.baeldung.commons.chain.AtmConstants.ATM_WITHDRAWAL_CHAIN;
+
+public class AtmCatalog extends CatalogBase {
+
+    public AtmCatalog() {
+        super();
+        addCommand(ATM_WITHDRAWAL_CHAIN, new AtmWithdrawalChain());
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/chain/AtmConstants.java

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+package com.baeldung.commons.chain;
+
+public class AtmConstants {
+    public static final String TOTAL_AMOUNT_TO_BE_WITHDRAWN = "totalAmountToBeWithdrawn";
+    public static final String AMOUNT_LEFT_TO_BE_WITHDRAWN = "amountLeftToBeWithdrawn";
+    public static final String NO_OF_HUNDREDS_DISPENSED = "noOfHundredsDispensed";
+    public static final String NO_OF_FIFTIES_DISPENSED = "noOfFiftiesDispensed";
+    public static final String NO_OF_TENS_DISPENSED = "noOfTensDispensed";
+    public static final String ATM_WITHDRAWAL_CHAIN = "atmWithdrawalChain";
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/chain/AtmRequestContext.java

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+package com.baeldung.commons.chain;
+
+import org.apache.commons.chain.impl.ContextBase;
+
+public class AtmRequestContext extends ContextBase {
+
+    int totalAmountToBeWithdrawn;
+    int noOfHundredsDispensed;
+    int noOfFiftiesDispensed;
+    int noOfTensDispensed;
+    int amountLeftToBeWithdrawn;
+
+    public int getTotalAmountToBeWithdrawn() {
+        return totalAmountToBeWithdrawn;
+    }
+
+    public void setTotalAmountToBeWithdrawn(int totalAmountToBeWithdrawn) {
+        this.totalAmountToBeWithdrawn = totalAmountToBeWithdrawn;
+    }
+
+    public int getNoOfHundredsDispensed() {
+        return noOfHundredsDispensed;
+    }
+
+    public void setNoOfHundredsDispensed(int noOfHundredsDispensed) {
+        this.noOfHundredsDispensed = noOfHundredsDispensed;
+    }
+
+    public int getNoOfFiftiesDispensed() {
+        return noOfFiftiesDispensed;
+    }
+
+    public void setNoOfFiftiesDispensed(int noOfFiftiesDispensed) {
+        this.noOfFiftiesDispensed = noOfFiftiesDispensed;
+    }
+
+    public int getNoOfTensDispensed() {
+        return noOfTensDispensed;
+    }
+
+    public void setNoOfTensDispensed(int noOfTensDispensed) {
+        this.noOfTensDispensed = noOfTensDispensed;
+    }
+
+    public int getAmountLeftToBeWithdrawn() {
+        return amountLeftToBeWithdrawn;
+    }
+
+    public void setAmountLeftToBeWithdrawn(int amountLeftToBeWithdrawn) {
+        this.amountLeftToBeWithdrawn = amountLeftToBeWithdrawn;
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/chain/AtmWithdrawalChain.java

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+package com.baeldung.commons.chain;
+
+import org.apache.commons.chain.impl.ChainBase;
+
+public class AtmWithdrawalChain extends ChainBase {
+
+    public AtmWithdrawalChain() {
+        super();
+        addCommand(new HundredDenominationDispenser());
+        addCommand(new FiftyDenominationDispenser());
+        addCommand(new TenDenominationDispenser());
+        addCommand(new AuditFilter());
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/chain/AuditFilter.java

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+package com.baeldung.commons.chain;
+
+import org.apache.commons.chain.Context;
+import org.apache.commons.chain.Filter;
+
+public class AuditFilter implements Filter {
+
+    @Override
+    public boolean postprocess(Context context, Exception exception) {
+        // Send notification to customer & bank.
+        return false;
+    }
+
+    @Override
+    public boolean execute(Context context) throws Exception {
+        return false;
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/chain/FiftyDenominationDispenser.java

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+package com.baeldung.commons.chain;
+
+import static com.baeldung.commons.chain.AtmConstants.NO_OF_FIFTIES_DISPENSED;
+
+public class FiftyDenominationDispenser extends AbstractDenominationDispenser {
+    @Override
+    protected String getDenominationString() {
+        return NO_OF_FIFTIES_DISPENSED;
+    }
+
+    @Override
+    protected int getDenominationValue() {
+        return 50;
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/chain/HundredDenominationDispenser.java

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+package com.baeldung.commons.chain;
+
+import static com.baeldung.commons.chain.AtmConstants.NO_OF_HUNDREDS_DISPENSED;
+
+public class HundredDenominationDispenser extends AbstractDenominationDispenser {
+    @Override
+    protected String getDenominationString() {
+        return NO_OF_HUNDREDS_DISPENSED;
+    }
+
+    @Override
+    protected int getDenominationValue() {
+        return 100;
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/chain/TenDenominationDispenser.java

@@ -0,0 +1,15 @@
+package com.baeldung.commons.chain;
+
+import static com.baeldung.commons.chain.AtmConstants.NO_OF_TENS_DISPENSED;
+
+public class TenDenominationDispenser extends AbstractDenominationDispenser {
+    @Override
+    protected String getDenominationString() {
+        return NO_OF_TENS_DISPENSED;
+    }
+
+    @Override
+    protected int getDenominationValue() {
+        return 10;
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/dbutils/Email.java

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+package com.baeldung.commons.dbutils;
+
+public class Email {
+    private Integer id;
+    private Integer employeeId;
+    private String address;
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public Integer getEmployeeId() {
+        return employeeId;
+    }
+
+    public void setEmployeeId(Integer employeeId) {
+        this.employeeId = employeeId;
+    }
+
+    public String getAddress() {
+        return address;
+    }
+
+    public void setAddress(String address) {
+        this.address = address;
+    }
+
+    @Override
+    public String toString() {
+        return "Email{" + "id=" + id + ", address=" + address + '}';
+    }
+
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/dbutils/Employee.java

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+package com.baeldung.commons.dbutils;
+
+import java.util.Date;
+import java.util.List;
+
+public class Employee {
+    private Integer id;
+    private String firstName;
+    private String lastName;
+    private Double salary;
+    private Date hiredDate;
+    private List<Email> emails;
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public Double getSalary() {
+        return salary;
+    }
+
+    public void setSalary(Double salary) {
+        this.salary = salary;
+    }
+
+    public Date getHiredDate() {
+        return hiredDate;
+    }
+
+    public void setHiredDate(Date hiredDate) {
+        this.hiredDate = hiredDate;
+    }
+
+    public List<Email> getEmails() {
+        return emails;
+    }
+
+    public void setEmails(List<Email> emails) {
+        this.emails = emails;
+    }
+
+    @Override
+    public String toString() {
+        return "Employee{" + "id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", salary=" + salary + ", hiredDate=" + hiredDate + '}';
+    }
+
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/dbutils/EmployeeHandler.java

@@ -0,0 +1,45 @@
+package com.baeldung.commons.dbutils;
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import org.apache.commons.dbutils.BasicRowProcessor;
+import org.apache.commons.dbutils.BeanProcessor;
+
+import org.apache.commons.dbutils.QueryRunner;
+import org.apache.commons.dbutils.handlers.BeanListHandler;
+
+public class EmployeeHandler extends BeanListHandler<Employee> {
+
+    private Connection connection;
+
+    public EmployeeHandler(Connection con) {
+        super(Employee.class, new BasicRowProcessor(new BeanProcessor(getColumnsToFieldsMap())));
+        this.connection = con;
+    }
+
+    @Override
+    public List<Employee> handle(ResultSet rs) throws SQLException {
+        List<Employee> employees = super.handle(rs);
+
+        QueryRunner runner = new QueryRunner();
+        BeanListHandler<Email> handler = new BeanListHandler<>(Email.class);
+        String query = "SELECT * FROM email WHERE employeeid = ?";
+        for (Employee employee : employees) {
+            List<Email> emails = runner.query(connection, query, handler, employee.getId());
+            employee.setEmails(emails);
+        }
+        return employees;
+    }
+
+    public static Map<String, String> getColumnsToFieldsMap() {
+        Map<String, String> columnsToFieldsMap = new HashMap<>();
+        columnsToFieldsMap.put("FIRST_NAME", "firstName");
+        columnsToFieldsMap.put("LAST_NAME", "lastName");
+        columnsToFieldsMap.put("HIRED_DATE", "hiredDate");
+        return columnsToFieldsMap;
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/lang3/BuilderMethods.java

@@ -0,0 +1,87 @@
+package com.baeldung.commons.lang3;
+
+import org.apache.commons.lang3.builder.EqualsBuilder;
+import org.apache.commons.lang3.builder.HashCodeBuilder;
+import org.apache.commons.lang3.builder.ToStringBuilder;
+import org.apache.commons.lang3.concurrent.ConcurrentException;
+import org.apache.commons.lang3.concurrent.BackgroundInitializer;
+
+public class BuilderMethods {
+
+    private final int intValue;
+    private final String strSample;
+
+    public BuilderMethods(final int newId, final String newName) {
+        this.intValue = newId;
+        this.strSample = newName;
+    }
+
+    public int getId() {
+        return this.intValue;
+    }
+
+    public String getName() {
+        return this.strSample;
+    }
+
+    @Override
+    public int hashCode() {
+        return new HashCodeBuilder().append(this.intValue).append(this.strSample).toHashCode();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj instanceof BuilderMethods == false) {
+            return false;
+        }
+        if (this == obj) {
+            return true;
+        }
+        final BuilderMethods otherObject = (BuilderMethods) obj;
+
+        return new EqualsBuilder().append(this.intValue, otherObject.intValue).append(this.strSample, otherObject.strSample).isEquals();
+    }
+
+    @Override
+    public String toString() {
+        return new ToStringBuilder(this).append("INTVALUE", this.intValue).append("STRINGVALUE", this.strSample).toString();
+    }
+
+    public static void main(final String[] arguments) {
+        final BuilderMethods simple1 = new BuilderMethods(1, "The First One");
+        System.out.println(simple1.getName());
+        System.out.println(simple1.hashCode());
+        System.out.println(simple1.toString());
+
+        SampleLazyInitializer sampleLazyInitializer = new SampleLazyInitializer();
+
+        try {
+            sampleLazyInitializer.get();
+        } catch (ConcurrentException e1) {
+            // TODO Auto-generated catch block
+            e1.printStackTrace();
+        }
+
+        SampleBackgroundInitializer sampleBackgroundInitializer = new SampleBackgroundInitializer();
+        sampleBackgroundInitializer.start();
+
+        // Proceed with other tasks instead of waiting for the SampleBackgroundInitializer task to finish.
+
+        try {
+            Object result = sampleBackgroundInitializer.get();
+        } catch (ConcurrentException e) {
+            e.printStackTrace();
+        }
+    }
+}
+
+class SampleBackgroundInitializer extends BackgroundInitializer<String> {
+
+    @Override
+    protected String initialize() throws Exception {
+        return null;
+    }
+
+    // Any complex task that takes some time
+
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/lang3/SampleLazyInitializer.java

@@ -0,0 +1,11 @@
+package com.baeldung.commons.lang3;
+
+import org.apache.commons.lang3.concurrent.LazyInitializer;
+
+public class SampleLazyInitializer extends LazyInitializer<SampleObject> {
+
+    @Override
+    protected SampleObject initialize() {
+        return new SampleObject();
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/lang3/SampleObject.java

@@ -0,0 +1,7 @@
+package com.baeldung.commons.lang3;
+
+public class SampleObject {
+
+    // Ignored
+
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/lang3/application/Application.java

@@ -0,0 +1,8 @@
+package com.baeldung.commons.lang3.application;
+
+public class Application {
+    
+    public static void main(String[] args) {
+        
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/lang3/beans/User.java

@@ -0,0 +1,25 @@
+package com.baeldung.commons.lang3.beans;
+
+public class User {
+
+    private final String name;
+    private final String email;
+
+    public User(String name, String email) {
+        this.name = name;
+        this.email = email;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    @Override
+    public String toString() {
+        return "User{" + "name=" + name + ", email=" + email + '}';
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/lang3/beans/UserInitializer.java

@@ -0,0 +1,11 @@
+package com.baeldung.commons.lang3.beans;
+
+import org.apache.commons.lang3.concurrent.LazyInitializer;
+
+public class UserInitializer extends LazyInitializer<User> {
+
+    @Override
+    protected User initialize() {
+        return new User("John", "[email protected]");
+    }
+}

libraries-apache-commons/src/main/java/com/baeldung/commons/math3/Histogram.java

@@ -0,0 +1,97 @@
+package com.baeldung.commons.math3;
+
+import org.apache.commons.math3.stat.Frequency;
+import org.knowm.xchart.CategoryChart;
+import org.knowm.xchart.CategoryChartBuilder;
+import org.knowm.xchart.SwingWrapper;
+import org.knowm.xchart.style.Styler;
+
+import java.util.*;
+
+public class Histogram {
+
+    private Map distributionMap;
+    private int classWidth;
+
+    public Histogram() {
+
+        distributionMap = new TreeMap();
+        classWidth = 10;
+        Map distributionMap = processRawData();
+        List yData = new ArrayList();
+        yData.addAll(distributionMap.values());
+        List xData = Arrays.asList(distributionMap.keySet().toArray());
+
+        CategoryChart chart = buildChart(xData, yData);
+        new SwingWrapper<>(chart).displayChart();
+
+    }
+
+    private CategoryChart buildChart(List xData, List yData) {
+
+        // Create Chart
+        CategoryChart chart = new CategoryChartBuilder().width(800).height(600)
+                .title("Age Distribution")
+                .xAxisTitle("Age Group")
+                .yAxisTitle("Frequency")
+                .build();
+
+        chart.getStyler().setLegendPosition(Styler.LegendPosition.InsideNW);
+        chart.getStyler().setAvailableSpaceFill(0.99);
+        chart.getStyler().setOverlapped(true);
+
+        chart.addSeries("age group", xData, yData);
+
+        return chart;
+    }
+
+    private Map processRawData() {
+
+        List<Integer> datasetList = Arrays.asList(
+          36, 25, 38, 46, 55, 68, 72,
+          55, 36, 38, 67, 45, 22, 48,
+          91, 46, 52, 61, 58, 55);
+        Frequency frequency = new Frequency();
+        datasetList.forEach(d -> frequency.addValue(Double.parseDouble(d.toString())));
+
+        datasetList.stream()
+          .map(d -> Double.parseDouble(d.toString()))
+          .distinct()
+          .forEach(observation -> {
+             long observationFrequency = frequency.getCount(observation);
+             int upperBoundary = (observation > classWidth)
+               ? Math.multiplyExact( (int) Math.ceil(observation / classWidth), classWidth)
+               : classWidth;
+             int lowerBoundary = (upperBoundary > classWidth)
+               ? Math.subtractExact(upperBoundary, classWidth)
+               : 0;
+             String bin = lowerBoundary + "-" + upperBoundary;
+
+             updateDistributionMap(lowerBoundary, bin, observationFrequency);
+
+          });
+
+        return distributionMap;
+    }
+
+    private void updateDistributionMap(int lowerBoundary, String bin, long observationFrequency) {
+
+        int prevLowerBoundary = (lowerBoundary > classWidth) ? lowerBoundary - classWidth : 0;
+        String prevBin = prevLowerBoundary + "-" + lowerBoundary;
+        if(!distributionMap.containsKey(prevBin))
+            distributionMap.put(prevBin, 0);
+
+        if(!distributionMap.containsKey(bin)) {
+            distributionMap.put(bin, observationFrequency);
+        }
+        else {
+            long oldFrequency = Long.parseLong(distributionMap.get(bin).toString());
+            distributionMap.replace(bin, oldFrequency + observationFrequency);
+        }
+    }
+
+    public static void main(String[] args) {
+        new Histogram();
+    }
+
+}

libraries-apache-commons/src/main/resources/logback.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

libraries-apache-commons/src/test/java/com/baeldung/commons/beanutils/CourseServiceUnitTest.java

@@ -0,0 +1,53 @@
+package com.baeldung.commons.beanutils;
+
+import java.lang.reflect.InvocationTargetException;
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class CourseServiceUnitTest {
+
+    @Test
+    public void givenCourse_whenSetValuesUsingPropertyUtil_thenReturnSetValues() throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
+        Course course = new Course();
+        String name = "Computer Science";
+        List<String> codes = Arrays.asList("CS", "CS01");
+        CourseService.setValues(course, name, codes);
+
+        Assert.assertEquals(name, course.getName());
+        Assert.assertEquals(2, course.getCodes().size());
+        Assert.assertEquals("CS", course.getCodes().get(0));
+
+        CourseService.setIndexedValue(course, 1, "CS02");
+        Assert.assertEquals("CS02", course.getCodes().get(1));
+
+        Student student = new Student();
+        String studentName = "Joe";
+        student.setName(studentName);
+
+        CourseService.setMappedValue(course, "ST-1", student);
+        Assert.assertEquals(student, course.getEnrolledStudent("ST-1"));
+
+        String accessedStudentName = CourseService.getNestedValue(course, "ST-1", "name");
+        Assert.assertEquals(studentName, accessedStudentName);
+    }
+
+    @Test
+    public void givenCopyProperties_whenCopyCourseToCourseEntity_thenCopyPropertyWithSameName() throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
+        Course course = new Course();
+        course.setName("Computer Science");
+        course.setCodes(Arrays.asList("CS"));
+        course.setEnrolledStudent("ST-1", new Student());
+
+        CourseEntity courseEntity = new CourseEntity();
+
+        CourseService.copyProperties(course, courseEntity);
+        Assert.assertNotNull(course.getName());
+	Assert.assertNotNull(courseEntity.getName());
+        Assert.assertEquals(course.getName(), courseEntity.getName());
+        Assert.assertEquals(course.getCodes(), courseEntity.getCodes());
+        Assert.assertNull(courseEntity.getStudent("ST-1"));
+    }
+}

libraries-apache-commons/src/test/java/com/baeldung/commons/chain/AtmChainUnitTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.commons.chain;
+
+import org.apache.commons.chain.Catalog;
+import org.apache.commons.chain.Command;
+import org.apache.commons.chain.Context;
+import org.junit.Assert;
+import org.junit.Test;
+
+import static com.baeldung.commons.chain.AtmConstants.*;
+
+public class AtmChainUnitTest {
+
+    public static final int EXPECTED_TOTAL_AMOUNT_TO_BE_WITHDRAWN = 460;
+    public static final int EXPECTED_AMOUNT_LEFT_TO_BE_WITHDRAWN = 0;
+    public static final int EXPECTED_NO_OF_HUNDREDS_DISPENSED = 4;
+    public static final int EXPECTED_NO_OF_FIFTIES_DISPENSED = 1;
+    public static final int EXPECTED_NO_OF_TENS_DISPENSED = 1;
+
+    @Test
+    public void givenInputsToContext_whenAppliedChain_thenExpectedContext() {
+        Context context = new AtmRequestContext();
+        context.put(TOTAL_AMOUNT_TO_BE_WITHDRAWN, 460);
+        context.put(AMOUNT_LEFT_TO_BE_WITHDRAWN, 460);
+        Catalog catalog = new AtmCatalog();
+        Command atmWithdrawalChain = catalog.getCommand(ATM_WITHDRAWAL_CHAIN);
+        try {
+            atmWithdrawalChain.execute(context);
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        Assert.assertEquals(EXPECTED_TOTAL_AMOUNT_TO_BE_WITHDRAWN, (int) context.get(TOTAL_AMOUNT_TO_BE_WITHDRAWN));
+        Assert.assertEquals(EXPECTED_AMOUNT_LEFT_TO_BE_WITHDRAWN, (int) context.get(AMOUNT_LEFT_TO_BE_WITHDRAWN));
+        Assert.assertEquals(EXPECTED_NO_OF_HUNDREDS_DISPENSED, (int) context.get(NO_OF_HUNDREDS_DISPENSED));
+        Assert.assertEquals(EXPECTED_NO_OF_FIFTIES_DISPENSED, (int) context.get(NO_OF_FIFTIES_DISPENSED));
+        Assert.assertEquals(EXPECTED_NO_OF_TENS_DISPENSED, (int) context.get(NO_OF_TENS_DISPENSED));
+    }
+}

libraries-apache-commons/src/test/java/com/baeldung/commons/dbutils/DbUtilsUnitTest.java

@@ -0,0 +1,155 @@
+package com.baeldung.commons.dbutils;
+
+import org.apache.commons.dbutils.AsyncQueryRunner;
+import org.apache.commons.dbutils.DbUtils;
+import org.apache.commons.dbutils.QueryRunner;
+import org.apache.commons.dbutils.handlers.BeanListHandler;
+import org.apache.commons.dbutils.handlers.MapListHandler;
+import org.apache.commons.dbutils.handlers.ScalarHandler;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.util.Date;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+public class DbUtilsUnitTest {
+
+    private Connection connection;
+
+    @Before
+    public void setupDB() throws Exception {
+        Class.forName("org.h2.Driver");
+        String db = "jdbc:h2:mem:;INIT=runscript from 'classpath:/employees.sql'";
+        connection = DriverManager.getConnection(db);
+    }
+
+    @After
+    public void closeBD() {
+        DbUtils.closeQuietly(connection);
+    }
+
+    @Test
+    public void givenResultHandler_whenExecutingQuery_thenExpectedList() throws SQLException {
+        MapListHandler beanListHandler = new MapListHandler();
+
+        QueryRunner runner = new QueryRunner();
+        List<Map<String, Object>> list = runner.query(connection, "SELECT * FROM employee", beanListHandler);
+
+        assertEquals(list.size(), 5);
+        assertEquals(list.get(0).get("firstname"), "John");
+        assertEquals(list.get(4).get("firstname"), "Christian");
+    }
+
+    @Test
+    public void givenResultHandler_whenExecutingQuery_thenEmployeeList() throws SQLException {
+        BeanListHandler<Employee> beanListHandler = new BeanListHandler<>(Employee.class);
+
+        QueryRunner runner = new QueryRunner();
+        List<Employee> employeeList = runner.query(connection, "SELECT * FROM employee", beanListHandler);
+
+        assertEquals(employeeList.size(), 5);
+        assertEquals(employeeList.get(0).getFirstName(), "John");
+        assertEquals(employeeList.get(4).getFirstName(), "Christian");
+    }
+
+    @Test
+    public void givenResultHandler_whenExecutingQuery_thenExpectedScalar() throws SQLException {
+        ScalarHandler<Long> scalarHandler = new ScalarHandler<>();
+
+        QueryRunner runner = new QueryRunner();
+        String query = "SELECT COUNT(*) FROM employee";
+        long count = runner.query(connection, query, scalarHandler);
+
+        assertEquals(count, 5);
+    }
+
+    @Test
+    public void givenResultHandler_whenExecutingQuery_thenEmailsSetted() throws SQLException {
+        EmployeeHandler employeeHandler = new EmployeeHandler(connection);
+
+        QueryRunner runner = new QueryRunner();
+        List<Employee> employees = runner.query(connection, "SELECT * FROM employee", employeeHandler);
+
+        assertEquals(employees.get(0).getEmails().size(), 2);
+        assertEquals(employees.get(2).getEmails().size(), 3);
+        assertNotNull(employees.get(0).getEmails().get(0).getEmployeeId());
+    }
+
+    @Test
+    public void givenResultHandler_whenExecutingQuery_thenAllPropertiesSetted() throws SQLException {
+        EmployeeHandler employeeHandler = new EmployeeHandler(connection);
+
+        QueryRunner runner = new QueryRunner();
+        String query = "SELECT * FROM employee_legacy";
+        List<Employee> employees = runner.query(connection, query, employeeHandler);
+
+        assertEquals((int) employees.get(0).getId(), 1);
+        assertEquals(employees.get(0).getFirstName(), "John");
+    }
+
+    @Test
+    public void whenInserting_thenInserted() throws SQLException {
+        QueryRunner runner = new QueryRunner();
+        String insertSQL = "INSERT INTO employee (firstname,lastname,salary, hireddate) VALUES (?, ?, ?, ?)";
+
+        int numRowsInserted = runner.update(connection, insertSQL, "Leia", "Kane", 60000.60, new Date());
+
+        assertEquals(numRowsInserted, 1);
+    }
+
+    @Test
+    public void givenHandler_whenInserting_thenExpectedId() throws SQLException {
+        ScalarHandler<Integer> scalarHandler = new ScalarHandler<>();
+
+        QueryRunner runner = new QueryRunner();
+        String insertSQL = "INSERT INTO employee (firstname,lastname,salary, hireddate) VALUES (?, ?, ?, ?)";
+
+        int newId = runner.insert(connection, insertSQL, scalarHandler, "Jenny", "Medici", 60000.60, new Date());
+
+        assertEquals(newId, 6);
+    }
+
+    @Test
+    public void givenSalary_whenUpdating_thenUpdated() throws SQLException {
+        double salary = 35000;
+
+        QueryRunner runner = new QueryRunner();
+        String updateSQL = "UPDATE employee SET salary = salary * 1.1 WHERE salary <= ?";
+        int numRowsUpdated = runner.update(connection, updateSQL, salary);
+
+        assertEquals(numRowsUpdated, 3);
+    }
+
+    @Test
+    public void whenDeletingRecord_thenDeleted() throws SQLException {
+        QueryRunner runner = new QueryRunner();
+        String deleteSQL = "DELETE FROM employee WHERE id = ?";
+        int numRowsDeleted = runner.update(connection, deleteSQL, 3);
+
+        assertEquals(numRowsDeleted, 1);
+    }
+
+    @Test
+    public void givenAsyncRunner_whenExecutingQuery_thenExpectedList() throws Exception {
+        AsyncQueryRunner runner = new AsyncQueryRunner(Executors.newCachedThreadPool());
+
+        EmployeeHandler employeeHandler = new EmployeeHandler(connection);
+        String query = "SELECT * FROM employee";
+        Future<List<Employee>> future = runner.query(connection, query, employeeHandler);
+        List<Employee> employeeList = future.get(10, TimeUnit.SECONDS);
+
+        assertEquals(employeeList.size(), 5);
+    }
+
+}