[BAEL-9555] - Created a core-java-modules folder

core-java-modules/core-java-os/.gitignore

@@ -0,0 +1,26 @@
+*.class
+
+0.*
+
+#folders#
+/target
+/neoDb*
+/data
+/src/main/webapp/WEB-INF/classes
+*/META-INF/*
+.resourceCache
+
+# Packaged files #
+*.jar
+*.war
+*.ear
+
+# Files generated by integration tests
+*.txt
+backup-pom.xml
+/bin/
+/temp
+
+#IntelliJ specific
+.idea/
+*.iml

core-java-modules/core-java-os/README.md

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+=========
+
+This module uses Java 9, so make sure to have the JDK 9 installed to run it.
+
+## 
+### Relevant Articles: 
+- [Java 9 Process API Improvements](http://www.baeldung.com/java-9-process-api)
+- [Guide to java.lang.Process API](https://www.baeldung.com/java-process-api)
+- [Guide to java.lang.ProcessBuilder API](https://www.baeldung.com/java-lang-processbuilder-api)
+

core-java-modules/core-java-os/pom.xml

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+<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>
+    <groupId>com.baeldung</groupId>
+    <artifactId>core-java-os</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-os</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>${commons-collections4.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>${commons-io.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>${log4j.version}</version>
+        </dependency>
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-os</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+
+        <plugins>
+         <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <source>${maven.compiler.source}</source>
+                    <target>${maven.compiler.target}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <!-- util -->
+        <commons-lang3.version>3.5</commons-lang3.version>
+        <commons-collections4.version>4.1</commons-collections4.version>
+        <collections-generic.version>4.01</collections-generic.version>
+    
+        <!-- testing -->
+        <assertj.version>3.6.1</assertj.version>
+        <asspectj.version>1.8.9</asspectj.version>
+        <maven.compiler.source>1.9</maven.compiler.source>
+        <maven.compiler.target>1.9</maven.compiler.target>
+        <guava.version>25.1-jre</guava.version>
+    </properties>
+</project>

core-java-modules/core-java-os/src/main/java/com/baeldung/java9/process/ChildProcess.java

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+package com.baeldung.java9.process;
+
+import java.util.Scanner;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class ChildProcess {
+
+    public static void main(String[] args) {
+        @SuppressWarnings("resource")
+        Scanner input = new Scanner(System.in);
+        Logger log = Logger.getLogger(ChildProcess.class.getName());
+        log.log(Level.INFO, input.nextLine());
+    }
+}

core-java-modules/core-java-os/src/main/java/com/baeldung/java9/process/OutputStreamExample.java

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+package com.baeldung.java9.process;
+
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class OutputStreamExample {
+
+    public static void main(String[] args) {
+        Logger log = Logger.getLogger(OutputStreamExample.class.getName());
+        log.log(Level.INFO, Integer.toString(sum(1,2)));
+    }
+
+    public static int sum(int a, int b) {
+        return a + b;
+    }
+}

core-java-modules/core-java-os/src/main/java/com/baeldung/java9/process/ProcessCompilationError.java

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+package com.baeldung.java9.process;
+
+public class ProcessCompilationError {
+    //This method has been written to generate error to display 
+    //how process errorStream() can consume error
+    //public static void();
+}

core-java-modules/core-java-os/src/main/java/com/baeldung/java9/process/ProcessUnderstanding.java

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+package com.baeldung.java9.process;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.util.Optional;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class ProcessUnderstanding {
+
+    public static int compileAndRunJavaProgram() throws IOException {
+        Process process = Runtime.getRuntime()
+            .exec("javac -cp src src\\main\\java\\com\\baeldung\\java9\\process\\OutputStreamExample.java");
+        process = Runtime.getRuntime()
+            .exec("java -cp  src/main/java com.baeldung.java9.process.OutputStreamExample");
+        BufferedReader output = new BufferedReader(new InputStreamReader(process.getInputStream()));
+        int value = Integer.parseInt(output.readLine());
+        return value;
+    }
+
+    public static String getErrorStreamExample() throws IOException {
+        Process process = Runtime.getRuntime()
+            .exec("javac -cp src src\\main\\java\\com\\baeldung\\java9\\process\\ProcessCompilationError.java");
+        BufferedReader error = new BufferedReader(new InputStreamReader(process.getErrorStream()));
+        String errorString = error.readLine();
+        return errorString;
+    }
+
+    public static void creatingNewProcess() throws IOException {
+        ProcessBuilder builder = new ProcessBuilder("notepad.exe");
+        Process process = builder.start();
+    }
+
+    public static int filterProcessWithStreamsInSpecificRangeReturnCount() {
+        return (int) ProcessHandle.allProcesses()
+            .filter(ph -> (ph.pid() > 10000 && ph.pid() < 50000))
+            .count();
+    }
+
+    public static void destroyingProcessCreatedBySameProcess() throws IOException, InterruptedException {
+        ProcessBuilder builder = new ProcessBuilder("notepad.exe");
+        Process process = builder.start();
+        Thread.sleep(10000);
+        process.destroy();
+    }
+
+    public static void destroyingProcessCreatedByDifferentProcess() {
+        // find out the process id of current running task by checking
+        // task manager in windows and enter the integer value
+        Optional<ProcessHandle> optionalProcessHandle = ProcessHandle.of(5232);
+        ProcessHandle processHandle = optionalProcessHandle.get();
+        processHandle.destroy();
+    }
+
+    public static int waitForExample() throws IOException, InterruptedException {
+        ProcessBuilder builder = new ProcessBuilder("notepad.exe");
+        Process process = builder.start();
+        return process.waitFor();
+    }
+
+    public static int exitValueExample() throws IOException {
+        ProcessBuilder builder = new ProcessBuilder("notepad.exe");
+        Process process = builder.start();
+        process.destroy();
+        return process.exitValue();
+    }
+
+    public static void destroyExample() throws IOException, InterruptedException {
+        ProcessBuilder builder = new ProcessBuilder("notepad.exe");
+        Process process = builder.start();
+        Thread.sleep(10000);
+        process.destroy();
+    }
+
+    public static void destroyForciblyExample() throws IOException, InterruptedException {
+        ProcessBuilder builder = new ProcessBuilder("notepad.exe");
+        Process process = builder.start();
+        Thread.sleep(10000);
+        process.destroy();
+        if (process.isAlive()) {
+            process.destroyForcibly();
+        }
+    }
+
+    public static void outputStreamDemo() throws IOException, InterruptedException {
+        Logger log = Logger.getLogger(ProcessUnderstanding.class.getName());
+        Process pr = Runtime.getRuntime()
+            .exec("javac -cp src src\\main\\java\\com\\baeldung\\java9\\process\\ChildProcess.java");
+        final Process process = Runtime.getRuntime()
+            .exec("java -cp  src/main/java com.baeldung.java9.process.ChildProcess");
+        try (Writer w = new OutputStreamWriter(process.getOutputStream(), "UTF-8")) {
+            w.write("send to child\n");
+        }
+        new Thread(() -> {
+            try {
+                int c;
+                while ((c = process.getInputStream()
+                    .read()) != -1)
+                    System.out.write((byte) c);
+            } catch (Exception e) {
+                e.printStackTrace();
+            }
+        }).start();
+        // send to child
+        log.log(Level.INFO, "rc=" + process.waitFor());
+    }
+}

core-java-modules/core-java-os/src/main/java/com/baeldung/java9/process/ProcessUtils.java

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+package com.baeldung.java9.process;
+
+import java.io.File;
+import java.io.IOException;
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.stream.Stream;
+
+public class ProcessUtils {
+
+    public static String getClassPath() {
+        String cp = System.getProperty("java.class.path");
+        System.out.println("ClassPath is " + cp);
+        return cp;
+    }
+
+    public static File getJavaCmd() throws IOException {
+        String javaHome = System.getProperty("java.home");
+        File javaCmd;
+        if (System.getProperty("os.name").startsWith("Win")) {
+            javaCmd = new File(javaHome, "bin/java.exe");
+        } else {
+            javaCmd = new File(javaHome, "bin/java");
+        }
+        if (javaCmd.canExecute()) {
+            return javaCmd;
+        } else {
+            throw new UnsupportedOperationException(javaCmd.getCanonicalPath() + " is not executable");
+        }
+    }
+
+    public static String getMainClass() {
+        return System.getProperty("sun.java.command");
+    }
+
+    public static String getSystemProperties() {
+        StringBuilder sb = new StringBuilder();
+        System.getProperties().forEach((s1, s2) -> sb.append(s1 + " - " + s2));
+        return sb.toString();
+    }
+}

core-java-modules/core-java-os/src/main/java/com/baeldung/java9/process/ServiceMain.java

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+package com.baeldung.java9.process;
+
+import java.util.Optional;
+
+public class ServiceMain {
+
+    public static void main(String[] args) throws InterruptedException {
+        ProcessHandle thisProcess = ProcessHandle.current();
+        long pid = thisProcess.pid();
+
+        Optional<String[]> opArgs = Optional.ofNullable(args);
+        String procName = opArgs.map(str -> str.length > 0 ? str[0] : null).orElse(System.getProperty("sun.java.command"));
+
+        for (int i = 0; i < 10000; i++) {
+            System.out.println("Process " + procName + " with ID " + pid + " is running!");
+            Thread.sleep(10000);
+        }
+
+    }
+
+}

core-java-modules/core-java-os/src/main/resources/logback.xml

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+<?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>

core-java-modules/core-java-os/src/test/java/com/baeldung/java9/process/ProcessAPIEnhancementsUnitTest.java

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+package com.baeldung.java9.process;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+import java.io.IOException;
+import java.util.concurrent.CompletableFuture;
+import java.util.stream.Stream;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Created by sanaulla on 2/23/2017.
+ */
+
+public class ProcessAPIEnhancementsUnitTest {
+
+    Logger log = LoggerFactory.getLogger(ProcessAPIEnhancementsUnitTest.class);
+
+    @Test
+    public void givenCurrentProcess_whenInvokeGetInfo_thenSuccess() throws IOException {
+        ProcessHandle processHandle = ProcessHandle.current();
+        ProcessHandle.Info processInfo = processHandle.info();
+        assertNotNull(processHandle.pid());
+        assertEquals(false, processInfo.arguments()
+          .isPresent());
+        assertEquals(true, processInfo.command()
+          .isPresent());
+        assertTrue(processInfo.command()
+          .get()
+          .contains("java"));
+
+        assertEquals(true, processInfo.startInstant()
+          .isPresent());
+        assertEquals(true, processInfo.totalCpuDuration()
+          .isPresent());
+        assertEquals(true, processInfo.user()
+          .isPresent());
+    }
+
+    @Test
+    public void givenSpawnProcess_whenInvokeGetInfo_thenSuccess() throws IOException {
+
+        String javaCmd = ProcessUtils.getJavaCmd()
+          .getAbsolutePath();
+        ProcessBuilder processBuilder = new ProcessBuilder(javaCmd, "-version");
+        Process process = processBuilder.inheritIO()
+          .start();
+        ProcessHandle processHandle = process.toHandle();
+        ProcessHandle.Info processInfo = processHandle.info();
+        assertNotNull(processHandle.pid());
+        assertEquals(false, processInfo.arguments()
+          .isPresent());
+        assertEquals(true, processInfo.command()
+          .isPresent());
+        assertTrue(processInfo.command()
+          .get()
+          .contains("java"));
+        assertEquals(true, processInfo.startInstant()
+          .isPresent());
+        assertEquals(true, processInfo.totalCpuDuration()
+          .isPresent());
+        assertEquals(true, processInfo.user()
+          .isPresent());
+    }
+
+    @Test
+    public void givenLiveProcesses_whenInvokeGetInfo_thenSuccess() {
+        Stream<ProcessHandle> liveProcesses = ProcessHandle.allProcesses();
+        liveProcesses.filter(ProcessHandle::isAlive)
+            .forEach(ph -> {
+                assertNotNull(ph.pid());
+                assertEquals(true, ph.info()
+                  .command()
+                  .isPresent());
+                assertEquals(true, ph.info()
+                  .startInstant()
+                  .isPresent());
+                assertEquals(true, ph.info()
+                  .totalCpuDuration()
+                  .isPresent());
+                assertEquals(true, ph.info()
+                  .user()
+                  .isPresent());
+            });
+    }
+
+    @Test
+    public void givenProcess_whenGetChildProcess_thenSuccess() throws IOException {
+        int childProcessCount = 5;
+        for (int i = 0; i < childProcessCount; i++) {
+            String javaCmd = ProcessUtils.getJavaCmd()
+              .getAbsolutePath();
+            ProcessBuilder processBuilder
+              = new ProcessBuilder(javaCmd, "-version");
+            processBuilder.inheritIO().start();
+        }
+
+        Stream<ProcessHandle> children = ProcessHandle.current()
+          .children();
+        children.filter(ProcessHandle::isAlive)
+          .forEach(ph -> log.info("PID: {}, Cmd: {}", ph.pid(), ph.info()
+            .command()));
+        Stream<ProcessHandle> descendants = ProcessHandle.current()
+          .descendants();
+        descendants.filter(ProcessHandle::isAlive)
+          .forEach(ph -> log.info("PID: {}, Cmd: {}", ph.pid(), ph.info()
+            .command()));
+    }
+
+    @Test
+    public void givenProcess_whenAddExitCallback_thenSuccess() throws Exception {
+        String javaCmd = ProcessUtils.getJavaCmd()
+          .getAbsolutePath();
+        ProcessBuilder processBuilder
+          = new ProcessBuilder(javaCmd, "-version");
+        Process process = processBuilder.inheritIO()
+          .start();
+        ProcessHandle processHandle = process.toHandle();
+
+        log.info("PID: {} has started", processHandle.pid());
+        CompletableFuture<ProcessHandle> onProcessExit = processHandle.onExit();
+        onProcessExit.get();
+        assertEquals(false, processHandle.isAlive());
+        onProcessExit.thenAccept(ph -> {
+            log.info("PID: {} has stopped", ph.pid());
+        });
+    }
+
+}

core-java-modules/core-java-os/src/test/java/com/baeldung/java9/process/ProcessApiUnitTest.java

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+package com.baeldung.java9.process;
+
+import java.io.IOException;
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
+import java.util.stream.Stream;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import junit.framework.Assert;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class ProcessApiUnitTest {
+
+    @Before
+    public void init() {
+
+    }
+
+    @Test
+    public void processInfoExample() throws NoSuchAlgorithmException {
+        ProcessHandle self = ProcessHandle.current();
+        long PID = self.pid();
+        ProcessHandle.Info procInfo = self.info();
+        Optional<String[]> args = procInfo.arguments();
+        Optional<String> cmd = procInfo.commandLine();
+        Optional<Instant> startTime = procInfo.startInstant();
+        Optional<Duration> cpuUsage = procInfo.totalCpuDuration();
+
+        waistCPU();
+        System.out.println("Args " + args);
+        System.out.println("Command " + cmd.orElse("EmptyCmd"));
+        System.out.println("Start time: " + startTime.get().toString());
+        System.out.println(cpuUsage.get().toMillis());
+
+        Stream<ProcessHandle> allProc = ProcessHandle.current().children();
+        allProc.forEach(p -> {
+            System.out.println("Proc " + p.pid());
+        });
+
+    }
+
+    @Test
+    public void createAndDestroyProcess() throws IOException, InterruptedException {
+        int numberOfChildProcesses = 5;
+        for (int i = 0; i < numberOfChildProcesses; i++) {
+            createNewJVM(ServiceMain.class, i).pid();
+        }
+
+        Stream<ProcessHandle> childProc = ProcessHandle.current().children();
+        assertEquals(childProc.count(), numberOfChildProcesses);
+
+        childProc = ProcessHandle.current().children();
+        childProc.forEach(processHandle -> {
+            assertTrue("Process " + processHandle.pid() + " should be alive!", processHandle.isAlive());
+            CompletableFuture<ProcessHandle> onProcExit = processHandle.onExit();
+            onProcExit.thenAccept(procHandle -> {
+                System.out.println("Process with PID " + procHandle.pid() + " has stopped");
+            });
+        });
+
+        Thread.sleep(10000);
+
+        childProc = ProcessHandle.current().children();
+        childProc.forEach(procHandle -> {
+            assertTrue("Could not kill process " + procHandle.pid(), procHandle.destroy());
+        });
+
+        Thread.sleep(5000);
+
+        childProc = ProcessHandle.current().children();
+        childProc.forEach(procHandle -> {
+            assertFalse("Process " + procHandle.pid() + " should not be alive!", procHandle.isAlive());
+        });
+
+    }
+
+    private Process createNewJVM(Class mainClass, int number) throws IOException {
+        ArrayList<String> cmdParams = new ArrayList<String>(5);
+        cmdParams.add(ProcessUtils.getJavaCmd().getAbsolutePath());
+        cmdParams.add("-cp");
+        cmdParams.add(ProcessUtils.getClassPath());
+        cmdParams.add(mainClass.getName());
+        cmdParams.add("Service " + number);
+        ProcessBuilder myService = new ProcessBuilder(cmdParams);
+        myService.inheritIO();
+        return myService.start();
+    }
+
+    private void waistCPU() throws NoSuchAlgorithmException {
+        ArrayList<Integer> randArr = new ArrayList<Integer>(4096);
+        SecureRandom sr = SecureRandom.getInstanceStrong();
+        Duration somecpu = Duration.ofMillis(4200L);
+        Instant end = Instant.now().plus(somecpu);
+        while (Instant.now().isBefore(end)) {
+            // System.out.println(sr.nextInt());
+            randArr.add(sr.nextInt());
+        }
+    }
+
+}

core-java-modules/core-java-os/src/test/java/com/baeldung/java9/process/ProcessUnderstandingUnitTest.java

@@ -0,0 +1,121 @@
+package com.baeldung.java9.process;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.lang.String;
+import java.util.Optional;
+import java.util.concurrent.TimeUnit;
+import java.lang.Integer;
+
+import org.junit.jupiter.api.Test;
+
+class ProcessUnderstandingUnitTest {
+
+    @Test
+    public void givenSourceProgram_whenExecutedFromAnotherProgram_thenSourceProgramOutput3() throws IOException {
+        Process process = Runtime.getRuntime()
+            .exec("javac -cp src src\\main\\java\\com\\baeldung\\java9\\process\\OutputStreamExample.java");
+        process = Runtime.getRuntime()
+            .exec("java -cp  src/main/java com.baeldung.java9.process.OutputStreamExample");
+        BufferedReader output = new BufferedReader(new InputStreamReader(process.getInputStream()));
+        int value = Integer.parseInt(output.readLine());
+        assertEquals(3, value);            
+    }
+
+    @Test
+    public void givenSourceProgram_whenReadingInputStream_thenFirstLineEquals3() throws IOException {
+        Process process = Runtime.getRuntime()
+            .exec("javac -cp src src\\main\\java\\com\\baeldung\\java9\\process\\OutputStreamExample.java");
+        process = Runtime.getRuntime()
+            .exec("java -cp  src/main/java com.baeldung.java9.process.OutputStreamExample");
+        BufferedReader output = new BufferedReader(new InputStreamReader(process.getInputStream()));
+        int value = Integer.parseInt(output.readLine());
+        assertEquals(3, value);                   
+    }
+
+    @Test
+    public void givenSubProcess_whenEncounteringError_thenErrorStreamNotNull() throws IOException {
+        Process process = Runtime.getRuntime()
+            .exec("javac -cp src src\\main\\java\\com\\baeldung\\java9\\process\\ProcessCompilationError.java");
+        BufferedReader error = new BufferedReader(new InputStreamReader(process.getErrorStream()));
+        String errorString = error.readLine();
+        assertNotNull(errorString);
+    }
+
+    //@Test - windows specific
+    public void givenSubProcess_whenStarted_thenStartSuccessIsAlive() throws IOException {
+        ProcessBuilder builder = new ProcessBuilder("notepad.exe");
+        assertTrue(builder.start().isAlive());
+    }
+
+    //@Test - windows specific
+    public void givenSubProcess_whenDestroying_thenProcessNotAlive() throws IOException, InterruptedException {
+        ProcessBuilder builder = new ProcessBuilder("notepad.exe");
+        Process process = builder.start();
+        Thread.sleep(10000);
+        process.destroy();
+        assertFalse(process.isAlive());
+    }
+
+    //@Test - windows specific
+    public void givenSubProcess_whenAlive_thenDestroyForcibly() throws IOException, InterruptedException {
+        ProcessBuilder builder = new ProcessBuilder("notepad.exe");
+        Process process = builder.start();
+        Thread.sleep(10000);
+        process.destroy();
+        if (process.isAlive()) {
+            process.destroyForcibly();
+        }
+        assertFalse(process.isAlive());
+    }
+
+    //@Test - windows specific
+    public void givenSubProcess_whenDestroyed_thenCheckIfAlive() throws IOException, InterruptedException {
+        ProcessBuilder builder = new ProcessBuilder("notepad.exe");
+        Process process = builder.start();
+        Thread.sleep(10000);
+        process.destroy();
+        assertFalse(process.isAlive());
+    }
+
+    @Test
+    public void givenProcessNotCreated_fromWithinJavaApplicationDestroying_thenProcessNotAlive() {
+        Optional<ProcessHandle> optionalProcessHandle = ProcessHandle.of(5232);
+        ProcessHandle processHandle = optionalProcessHandle.get();
+        processHandle.destroy();
+        assertFalse(processHandle.isAlive());
+    }
+
+    //@Test - windows specific
+    public void givenSubProcess_whenCurrentThreadWaitsIndefinitelyuntilSubProcessEnds_thenProcessWaitForReturnsGrt0() throws IOException, InterruptedException {
+        ProcessBuilder builder = new ProcessBuilder("notepad.exe");
+        Process process = builder.start();
+        assertThat(process.waitFor() >= 0);
+    }
+
+    //@Test - windows specific
+    public void givenSubProcess_whenCurrentThreadWaitsAndSubProcessNotTerminated_thenProcessWaitForReturnsFalse() throws IOException, InterruptedException {
+        ProcessBuilder builder = new ProcessBuilder("notepad.exe");
+        Process process = builder.start();
+        assertFalse(process.waitFor(1, TimeUnit.SECONDS));
+    }
+
+    //@Test - windows specific
+    public void givenSubProcess_whenCurrentThreadWillNotWaitIndefinitelyforSubProcessToEnd_thenProcessExitValueReturnsGrt0() throws IOException {
+        ProcessBuilder builder = new ProcessBuilder("notepad.exe");
+        Process process = builder.start();
+        assertThat(process.exitValue() >= 0);
+    }
+
+    @Test
+    public void givenRunningProcesses_whenFilterOnProcessIdRange_thenGetSelectedProcessPid() {
+        assertThat(((int) ProcessHandle.allProcesses()
+            .filter(ph -> (ph.pid() > 10000 && ph.pid() < 50000))
+            .count()) > 0);
+    }
+}

core-java-modules/core-java-os/src/test/java/com/baeldung/processbuilder/ProcessBuilderUnitTest.java

@@ -0,0 +1,182 @@
+package com.baeldung.processbuilder;
+
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.empty;
+import static org.hamcrest.Matchers.hasItem;
+import static org.hamcrest.Matchers.hasItems;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.not;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.lang.ProcessBuilder.Redirect;
+import java.nio.file.Files;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ExecutionException;
+import java.util.stream.Collectors;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+public class ProcessBuilderUnitTest {
+
+    @Rule
+    public TemporaryFolder tempFolder = new TemporaryFolder();
+
+    @Test
+    public void givenProcessBuilder_whenInvokeStart_thenSuccess() throws IOException, InterruptedException, ExecutionException {
+        ProcessBuilder processBuilder = new ProcessBuilder("java", "-version");
+        processBuilder.redirectErrorStream(true);
+
+        Process process = processBuilder.start();
+
+        List<String> results = readOutput(process.getInputStream());
+        assertThat("Results should not be empty", results, is(not(empty())));
+        assertThat("Results should contain java version: ", results, hasItem(containsString("java version")));
+
+        int exitCode = process.waitFor();
+        assertEquals("No errors should be detected", 0, exitCode);
+    }
+
+    @Test
+    public void givenProcessBuilder_whenModifyEnvironment_thenSuccess() throws IOException, InterruptedException {
+        ProcessBuilder processBuilder = new ProcessBuilder();
+        Map<String, String> environment = processBuilder.environment();
+        environment.forEach((key, value) -> System.out.println(key + value));
+
+        environment.put("GREETING", "Hola Mundo");
+
+        List<String> command = getGreetingCommand();
+        processBuilder.command(command);
+        Process process = processBuilder.start();
+
+        List<String> results = readOutput(process.getInputStream());
+        assertThat("Results should not be empty", results, is(not(empty())));
+        assertThat("Results should contain a greeting ", results, hasItem(containsString("Hola Mundo")));
+
+        int exitCode = process.waitFor();
+        assertEquals("No errors should be detected", 0, exitCode);
+    }
+
+    @Test
+    public void givenProcessBuilder_whenModifyWorkingDir_thenSuccess() throws IOException, InterruptedException {
+        List<String> command = getDirectoryListingCommand();
+        ProcessBuilder processBuilder = new ProcessBuilder(command);
+
+        processBuilder.directory(new File("src"));
+        Process process = processBuilder.start();
+
+        List<String> results = readOutput(process.getInputStream());
+        assertThat("Results should not be empty", results, is(not(empty())));
+        assertThat("Results should contain directory listing: ", results, hasItems(containsString("main"), containsString("test")));
+
+        int exitCode = process.waitFor();
+        assertEquals("No errors should be detected", 0, exitCode);
+    }
+
+    @Test
+    public void givenProcessBuilder_whenRedirectStandardOutput_thenSuccessWriting() throws IOException, InterruptedException {
+        ProcessBuilder processBuilder = new ProcessBuilder("java", "-version");
+
+        processBuilder.redirectErrorStream(true);
+        File log = tempFolder.newFile("java-version.log");
+        processBuilder.redirectOutput(log);
+
+        Process process = processBuilder.start();
+
+        assertEquals("If redirected, should be -1 ", -1, process.getInputStream()
+            .read());
+        int exitCode = process.waitFor();
+        assertEquals("No errors should be detected", 0, exitCode);
+
+        List<String> lines = Files.lines(log.toPath())
+            .collect(Collectors.toList());
+
+        assertThat("Results should not be empty", lines, is(not(empty())));
+        assertThat("Results should contain java version: ", lines, hasItem(containsString("java version")));
+    }
+
+    @Test
+    public void givenProcessBuilder_whenRedirectStandardOutput_thenSuccessAppending() throws IOException, InterruptedException {
+        ProcessBuilder processBuilder = new ProcessBuilder("java", "-version");
+
+        File log = tempFolder.newFile("java-version-append.log");
+        processBuilder.redirectErrorStream(true);
+        processBuilder.redirectOutput(Redirect.appendTo(log));
+
+        Process process = processBuilder.start();
+
+        assertEquals("If redirected output, should be -1 ", -1, process.getInputStream()
+            .read());
+
+        int exitCode = process.waitFor();
+        assertEquals("No errors should be detected", 0, exitCode);
+
+        List<String> lines = Files.lines(log.toPath())
+            .collect(Collectors.toList());
+
+        assertThat("Results should not be empty", lines, is(not(empty())));
+        assertThat("Results should contain java version: ", lines, hasItem(containsString("java version")));
+    }
+
+    @Test
+    public void givenProcessBuilder_whenStartingPipeline_thenSuccess() throws IOException, InterruptedException {
+        if (!isWindows()) {
+            List<ProcessBuilder> builders = Arrays.asList(
+                new ProcessBuilder("find", "src", "-name", "*.java", "-type", "f"), 
+                new ProcessBuilder("wc", "-l"));
+
+            List<Process> processes = ProcessBuilder.startPipeline(builders);
+            Process last = processes.get(processes.size() - 1);
+
+            List<String> output = readOutput(last.getInputStream());
+            assertThat("Results should not be empty", output, is(not(empty())));
+        }
+    }
+    
+    @Test
+    public void givenProcessBuilder_whenInheritIO_thenSuccess() throws IOException, InterruptedException {
+        List<String> command = getEchoCommand();
+        ProcessBuilder processBuilder = new ProcessBuilder(command);
+
+        processBuilder.inheritIO();
+        Process process = processBuilder.start();
+
+        int exitCode = process.waitFor();
+        assertEquals("No errors should be detected", 0, exitCode);
+    }
+
+    private List<String> readOutput(InputStream inputStream) throws IOException {
+        try (BufferedReader output = new BufferedReader(new InputStreamReader(inputStream))) {
+            return output.lines()
+                .collect(Collectors.toList());
+        }
+    }
+
+    private List<String> getDirectoryListingCommand() {
+        return isWindows() ? Arrays.asList("cmd.exe", "/c", "dir") : Arrays.asList("/bin/sh", "-c", "ls");
+    }
+
+    private List<String> getGreetingCommand() {
+        return isWindows() ? Arrays.asList("cmd.exe", "/c", "echo %GREETING%") : Arrays.asList("/bin/bash", "-c", "echo $GREETING");
+    }
+
+    private List<String> getEchoCommand() {
+        return isWindows() ? Arrays.asList("cmd.exe", "/c", "echo hello") : Arrays.asList("/bin/sh", "-c", "echo hello");
+    }
+
+    private boolean isWindows() {
+        return System.getProperty("os.name")
+            .toLowerCase()
+            .startsWith("windows");
+    }
+
+}

core-java-modules/core-java-os/src/test/resources/.gitignore

@@ -0,0 +1,13 @@
+*.class
+
+#folders#
+/target
+/neoDb*
+/data
+/src/main/webapp/WEB-INF/classes
+*/META-INF/*
+
+# Packaged files #
+*.jar
+*.war
+*.ear