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BAEL-3215: A Guide to the Java FileReader Class (eugenp#7677)
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‎core-java-modules/core-java-io-2/.gitignore

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# Intellij
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.idea/
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*.iml

‎core-java-modules/core-java-io-2/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"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<artifactId>core-java-io-2</artifactId>
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<version>0.1.0-SNAPSHOT</version>
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<name>core-java-io-2</name>
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<packaging>jar</packaging>
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<parent>
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<groupId>com.baeldung</groupId>
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<artifactId>parent-java</artifactId>
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<version>0.0.1-SNAPSHOT</version>
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<relativePath>../../parent-java</relativePath>
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</parent>
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<dependencies>
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<!-- utils -->
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<dependency>
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<groupId>net.sourceforge.collections</groupId>
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<artifactId>collections-generic</artifactId>
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<version>${collections-generic.version}</version>
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</dependency>
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<dependency>
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<groupId>org.apache.commons</groupId>
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<artifactId>commons-collections4</artifactId>
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<version>${commons-collections4.version}</version>
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</dependency>
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<dependency>
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<groupId>commons-io</groupId>
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<artifactId>commons-io</artifactId>
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<version>${commons-io.version}</version>
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</dependency>
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<dependency>
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<groupId>org.apache.commons</groupId>
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<artifactId>commons-lang3</artifactId>
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<version>${commons-lang3.version}</version>
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</dependency>
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<dependency>
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<groupId>org.apache.commons</groupId>
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<artifactId>commons-math3</artifactId>
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<version>${commons-math3.version}</version>
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</dependency>
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<dependency>
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<groupId>org.decimal4j</groupId>
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<artifactId>decimal4j</artifactId>
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<version>${decimal4j.version}</version>
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</dependency>
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<dependency>
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<groupId>org.bouncycastle</groupId>
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<artifactId>bcprov-jdk15on</artifactId>
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<version>${bouncycastle.version}</version>
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</dependency>
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<dependency>
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<groupId>org.unix4j</groupId>
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<artifactId>unix4j-command</artifactId>
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<version>${unix4j.version}</version>
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</dependency>
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<dependency>
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<groupId>com.googlecode.grep4j</groupId>
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<artifactId>grep4j</artifactId>
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<version>${grep4j.version}</version>
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</dependency>
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<!-- web -->
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<!-- marshalling -->
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<dependency>
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<groupId>com.fasterxml.jackson.core</groupId>
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<artifactId>jackson-databind</artifactId>
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<version>${jackson.version}</version>
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</dependency>
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<!-- logging -->
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<dependency>
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<groupId>log4j</groupId>
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<artifactId>log4j</artifactId>
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<version>${log4j.version}</version>
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</dependency>
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<dependency> <!-- needed to bridge to slf4j for projects that use the log4j APIs directly -->
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<groupId>org.slf4j</groupId>
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<artifactId>log4j-over-slf4j</artifactId>
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<version>${org.slf4j.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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<version>${lombok.version}</version>
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<scope>provided</scope>
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</dependency>
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<!-- test scoped -->
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<dependency>
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<groupId>org.assertj</groupId>
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<artifactId>assertj-core</artifactId>
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<version>${assertj.version}</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>com.jayway.awaitility</groupId>
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<artifactId>awaitility</artifactId>
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<version>${avaitility.version}</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>commons-codec</groupId>
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<artifactId>commons-codec</artifactId>
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<version>${commons-codec.version}</version>
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</dependency>
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<dependency>
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<groupId>org.javamoney</groupId>
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<artifactId>moneta</artifactId>
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<version>${moneta.version}</version>
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</dependency>
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<dependency>
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<groupId>org.owasp.esapi</groupId>
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<artifactId>esapi</artifactId>
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<version>${esapi.version}</version>
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</dependency>
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<dependency>
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<groupId>com.sun.messaging.mq</groupId>
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<artifactId>fscontext</artifactId>
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<version>${fscontext.version}</version>
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</dependency>
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<dependency>
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<groupId>com.codepoetics</groupId>
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<artifactId>protonpack</artifactId>
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<version>${protonpack.version}</version>
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</dependency>
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<dependency>
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<groupId>one.util</groupId>
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<artifactId>streamex</artifactId>
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<version>${streamex.version}</version>
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</dependency>
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<dependency>
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<groupId>io.vavr</groupId>
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<artifactId>vavr</artifactId>
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<version>${vavr.version}</version>
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</dependency>
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<dependency>
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<groupId>org.openjdk.jmh</groupId>
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<artifactId>jmh-core</artifactId>
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<version>${jmh-core.version}</version>
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</dependency>
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<dependency>
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<groupId>org.openjdk.jmh</groupId>
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<artifactId>jmh-generator-annprocess</artifactId>
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<version>${jmh-generator-annprocess.version}</version>
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</dependency>
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<dependency>
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<groupId>org.hsqldb</groupId>
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<artifactId>hsqldb</artifactId>
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<version>${hsqldb.version}</version>
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<scope>runtime</scope>
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</dependency>
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<!-- https://mvnrepository.com/artifact/org.asynchttpclient/async-http-client -->
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<dependency>
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<groupId>org.asynchttpclient</groupId>
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<artifactId>async-http-client</artifactId>
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<version>${async-http-client.version}</version>
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</dependency>
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<dependency>
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<groupId>com.opencsv</groupId>
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<artifactId>opencsv</artifactId>
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<version>${opencsv.version}</version>
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<scope>test</scope>
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</dependency>
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<!-- Mime Type Resolution Libraries -->
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<dependency>
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<groupId>org.apache.tika</groupId>
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<artifactId>tika-core</artifactId>
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<version>${tika.version}</version>
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</dependency>
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<dependency>
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<groupId>net.sf.jmimemagic</groupId>
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<artifactId>jmimemagic</artifactId>
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<version>${jmime-magic.version}</version>
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</dependency>
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</dependencies>
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<build>
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<finalName>core-java-io-2</finalName>
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<resources>
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<resource>
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<directory>src/main/resources</directory>
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<filtering>true</filtering>
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</resource>
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</resources>
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<plugins>
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<plugin>
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<groupId>org.codehaus.mojo</groupId>
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<artifactId>exec-maven-plugin</artifactId>
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<version>${exec-maven-plugin.version}</version>
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<configuration>
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<executable>java</executable>
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<mainClass>com.baeldung.outofmemoryerror.OutOfMemoryGCLimitExceed</mainClass>
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<arguments>
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<argument>-Xmx300m</argument>
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<argument>-XX:+UseParallelGC</argument>
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<argument>-classpath</argument>
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<classpath />
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<argument>com.baeldung.outofmemoryerror.OutOfMemoryGCLimitExceed</argument>
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</arguments>
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</configuration>
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</plugin>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-javadoc-plugin</artifactId>
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<version>${maven-javadoc-plugin.version}</version>
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<configuration>
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<source>${maven.compiler.source}</source>
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<target>${maven.compiler.target}</target>
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</configuration>
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</plugin>
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</plugins>
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</build>
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<profiles>
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<profile>
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<id>integration</id>
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<build>
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<plugins>
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<plugin>
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<groupId>org.codehaus.mojo</groupId>
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<artifactId>exec-maven-plugin</artifactId>
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<executions>
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<execution>
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<id>run-benchmarks</id>
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<!-- <phase>integration-test</phase> -->
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<phase>none</phase>
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<goals>
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<goal>exec</goal>
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</goals>
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<configuration>
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<classpathScope>test</classpathScope>
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<executable>java</executable>
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<arguments>
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<argument>-classpath</argument>
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<classpath />
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<argument>org.openjdk.jmh.Main</argument>
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<argument>.*</argument>
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</arguments>
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</configuration>
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</execution>
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</executions>
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</plugin>
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</plugins>
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</build>
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</profile>
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</profiles>
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<properties>
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<!-- util -->
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<bouncycastle.version>1.55</bouncycastle.version>
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<commons-codec.version>1.10</commons-codec.version>
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<commons-math3.version>3.6.1</commons-math3.version>
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<decimal4j.version>1.0.3</decimal4j.version>
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<commons-collections4.version>4.1</commons-collections4.version>
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<collections-generic.version>4.01</collections-generic.version>
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<unix4j.version>0.4</unix4j.version>
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<grep4j.version>1.8.7</grep4j.version>
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<fscontext.version>4.6-b01</fscontext.version>
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<protonpack.version>1.13</protonpack.version>
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<streamex.version>0.6.5</streamex.version>
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<vavr.version>0.9.0</vavr.version>
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<opencsv.version>4.1</opencsv.version>
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<!-- testing -->
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<assertj.version>3.6.1</assertj.version>
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<avaitility.version>1.7.0</avaitility.version>
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<!-- maven plugins -->
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<maven-javadoc-plugin.version>3.0.0-M1</maven-javadoc-plugin.version>
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<hsqldb.version>2.4.0</hsqldb.version>
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<esapi.version>2.1.0.1</esapi.version>
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<jmh-generator-annprocess.version>1.19</jmh-generator-annprocess.version>
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<async-http-client.version>2.4.5</async-http-client.version>
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<!-- Mime Type Libraries -->
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<tika.version>1.18</tika.version>
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<jmime-magic.version>0.1.5</jmime-magic.version>
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</properties>
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</project>

‎core-java-modules/core-java-io-2/src/main/java/com/baeldung/filereader/FileReaderExample.java

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package com.baeldung.filereader;
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import java.io.*;
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public class FileReaderExample {
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public static String readAllCharactersOneByOne(Reader reader) throws IOException {
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StringBuilder content = new StringBuilder();
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int nextChar;
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while ((nextChar = reader.read()) != -1) {
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content.append((char) nextChar);
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}
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return String.valueOf(content);
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}
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public static String readMultipleCharacters(Reader reader, int length) throws IOException {
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char[] buffer = new char[length];
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int charactersRead = reader.read(buffer, 0, length);
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if (charactersRead != -1) {
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return new String(buffer, 0, charactersRead);
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} else {
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return "";
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}
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}
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public static String readFile(String path) {
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FileReader fileReader = null;
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try {
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fileReader = new FileReader(path);
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return readAllCharactersOneByOne(fileReader);
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} catch (IOException e) {
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e.printStackTrace();
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} finally {
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if (fileReader != null) {
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try {
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fileReader.close();
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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}
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return null;
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}
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public static String readFileUsingTryWithResources(String path) {
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try (FileReader fileReader = new FileReader(path)) {
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return readAllCharactersOneByOne(fileReader);
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} catch (IOException e) {
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e.printStackTrace();
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}
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return null;
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}
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}

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