JAVA-19116 Create new core-java-compiler sub module under core-java-modules (#13658)

* JAVA-19116 Create new core-java-compiler sub module under core-java-modules

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

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+## Core Java Compiler
+
+### Relevant Articles: 
+
+- [Compiling Java *.class Files with javac](http://www.baeldung.com/javac)
+- [Illegal Character Compilation Error](https://www.baeldung.com/java-illegal-character-error)

core-java-modules/core-java-compiler/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-compiler</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-compiler</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>com.google.gdata</groupId>
+            <artifactId>core</artifactId>
+            <version>${gdata.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <gdata.version>1.47.1</gdata.version>
+    </properties>
+
+</project>

core-java-modules/core-java-compiler/src/main/java/com/baeldung/javac/Data.java

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+package com.baeldung.javac;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Data {
+    List<String> textList = new ArrayList();
+
+    public void addText(String text) {
+        textList.add(text);
+    }
+
+    public List getTextList() {
+        return this.textList;
+    }
+}

core-java-modules/core-java-compiler/src/main/java/javac-args/arguments

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+-d javac-target -verbose
+com/baeldung/javac/Data.java

core-java-modules/core-java-compiler/src/main/java/javac-args/options

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+-d javac-target
+-verbose

core-java-modules/core-java-compiler/src/main/java/javac-args/types

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+com/baeldung/javac/Data.java

core-java-modules/core-java-compiler/src/main/java/javac-args/xlint-ops

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+-d javac-target
+-Xlint:rawtypes,unchecked,static,cast,serial,fallthrough
+com/baeldung/javac/Data.java

core-java-modules/core-java-compiler/src/test/java/com/baeldung/illegalcharacter/IllegalCharacterUnitTest.java

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+package com.baeldung.illegalcharacter;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.nio.charset.StandardCharsets;
+import java.util.Objects;
+
+import org.apache.commons.io.ByteOrderMark;
+import org.apache.commons.io.input.BOMInputStream;
+import org.junit.Test;
+
+import com.google.gdata.util.io.base.UnicodeReader;
+
+public class IllegalCharacterUnitTest {
+
+    final String RESOURCE_FILE_NAME = "bom-file.txt";
+    final InputStream ioStream = this.getClass()
+        .getClassLoader()
+        .getResourceAsStream(RESOURCE_FILE_NAME);
+    final String expected = "Hello world with BOM.";
+
+    @Test
+    public void whenInputFileHasBOM_thenUseInputStream() throws IOException {
+        String line;
+        String actual = "";
+
+        try (BufferedReader br = new BufferedReader(new InputStreamReader(ioStream))) {
+            while ((line = br.readLine()) != null) {
+                actual += line;
+            }
+        }
+
+        assertNotEquals(expected, actual);
+    }
+
+    @Test
+    public void whenInputFileHasBOM_thenUseInputStreamWithReplace() throws IOException {
+        String line;
+        String actual = "";
+
+        try (BufferedReader br = new BufferedReader(new InputStreamReader(Objects.requireNonNull(ioStream), StandardCharsets.UTF_8))) {
+            while ((line = br.readLine()) != null) {
+                actual += line.replace("\uFEFF", "");
+            }
+        }
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void whenInputFileHasBOM_thenUseBOMInputStream() throws IOException {
+        String line;
+        String actual = "";
+
+        try (BufferedReader br = new BufferedReader(new InputStreamReader(new BOMInputStream(ioStream, false, ByteOrderMark.UTF_8, ByteOrderMark.UTF_16BE, ByteOrderMark.UTF_16LE, ByteOrderMark.UTF_32BE, ByteOrderMark.UTF_32LE)))) {
+            while ((line = br.readLine()) != null) {
+                actual += line;
+            }
+        }
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void whenInputFileHasBOM_thenUseGoogleGdata() throws IOException {
+        char[] actual = new char[21];
+
+        try (Reader r = new UnicodeReader(ioStream, null)) {
+            r.read(actual);
+        }
+
+        assertEquals(expected, String.valueOf(actual));
+    }
+}

core-java-modules/core-java-compiler/src/test/resources/bom-file.txt

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+Hello world with BOM.