Merge pull request #13341 from StefSC/BAEL-5788

[BAEL-5788] Accessing Private Constructor

core-java-modules/core-java-reflection-private-constructor/README.md

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+### Relevant Articles:
+
+- [Reading the Value of ‘private’ Fields from a Different Class in Java](https://www.baeldung.com/java-reflection-read-private-field-value)
+- [Set Field Value With Reflection](https://www.baeldung.com/java-set-private-field-value)
+- [Checking If a Method is Static Using Reflection in Java](https://www.baeldung.com/java-check-method-is-static)
+- [Checking if a Java Class is ‘abstract’ Using Reflection](https://www.baeldung.com/java-reflection-is-class-abstract)
+- [Invoking a Private Method in Java](https://www.baeldung.com/java-call-private-method)
+- [Finding All Classes in a Java Package](https://www.baeldung.com/java-find-all-classes-in-package)
+- [Invoke a Static Method Using Java Reflection API](https://www.baeldung.com/java-invoke-static-method-reflection)
+- [What Is the JDK com.sun.proxy.$Proxy Class?](https://www.baeldung.com/jdk-com-sun-proxy)

core-java-modules/core-java-reflection-private-constructor/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>core-java-reflection-private-constructor</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-reflection-private-constructor</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-test</artifactId>
+            <version>${spring.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.reflections</groupId>
+            <artifactId>reflections</artifactId>
+            <version>${reflections.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-reflection-private-constructor</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <source>${source.version}</source>
+                    <target>${target.version}</target>
+                    <compilerArgument>-parameters</compilerArgument>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <reflections.version>0.9.12</reflections.version>
+        <source.version>1.8</source.version>
+        <target.version>1.8</target.version>
+        <spring.version>5.3.4</spring.version>
+    </properties>
+
+</project>

core-java-modules/core-java-reflection-private-constructor/src/main/java/com/baeldung/reflection/PrivateConstructorClass.java

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+package com.baeldung.reflection;
+
+public class PrivateConstructorClass {
+
+    private PrivateConstructorClass() {
+        System.out.println("Used the private constructor!");
+    }
+}

core-java-modules/core-java-reflection-private-constructor/src/test/java/com/baeldung/reflection/PrivateConstructorUnitTest.java

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+package com.baeldung.reflection;
+
+import java.lang.reflect.Constructor;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class PrivateConstructorUnitTest {
+
+    @Test
+    public void whenConstructorIsPrivate_thenInstanceSuccess() throws Exception {
+        Constructor<PrivateConstructorClass> pcc = PrivateConstructorClass.class.getDeclaredConstructor();
+        pcc.setAccessible(true);
+        PrivateConstructorClass privateConstructorInstance = pcc.newInstance();
+        Assertions.assertTrue(privateConstructorInstance instanceof PrivateConstructorClass);
+    }
+}