Different Ways to Convert InputStream to String in Java | Code Factory

3 min readApr 16, 2020

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CodeFactory.txt

Hello
Code Factory!!!

Convert InputStream to String using BufferedReader

BufferedReaderExample.java

package com.codeFactory;import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;/**
 * @author code.factory
 *
 */
public class BufferedReaderExample {public static void main(String... args) {
  InputStream inputStream = null;
  BufferedReader bufferedReader = null;StringBuilder stringBuilder = new StringBuilder();
  String text;
  try {
   inputStream = new FileInputStream(new File("files/CodeFactory.txt"));
   bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
   while ((text = bufferedReader.readLine()) != null) {
    stringBuilder.append(text);
    stringBuilder.append("\n");
   }
   System.out.println(stringBuilder);
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
 }
}

2. Convert InputStream to String using Scanner

ScannerExample.java

package com.codeFactory;import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.util.Scanner;/**
 * @author code.factory
 *
 */
public class ScannerExample {public static void main(String... args) {
  InputStream inputStream = null;
  Scanner scanner = null;StringBuilder stringBuilder = new StringBuilder();
  try {
   inputStream = new FileInputStream(new File("files/CodeFactory.txt"));
   scanner = new Scanner(inputStream, "UTF-8").useDelimiter("\\n");
   while (scanner.hasNext()) {
    stringBuilder.append(scanner.next());
   }
   System.out.println(stringBuilder);
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  }
 }
}

3. Convert InputStream to String using Stream API Collect

CollectAPIExample.java

package com.codeFactory;import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.stream.Collectors;/**
 * @author code.factory
 *
 */
public class CollectAPIExample {public static void main(String... args) {
  InputStream inputStream = null;
  try {
   inputStream = new FileInputStream(new File("files/CodeFactory.txt"));String result = new BufferedReader(new InputStreamReader(inputStream))
     .lines().collect(Collectors.joining("\n"));System.out.println(result);
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  }
 }
}

4. Convert InputStream to String using Stream API Parallel

ParallelExample.java

package com.codeFactory;import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.stream.Collectors;/**
 * @author code.factory
 *
 */
public class ParallelExample {public static void main(String... args) {
  InputStream inputStream = null;
  try {
   inputStream = new FileInputStream(new File("files/CodeFactory.txt"));String result = new BufferedReader(new InputStreamReader(inputStream))
     .lines().parallel().collect(Collectors.joining("\n"));System.out.println(result);
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  }
 }
}

5. Convert InputStream to String using ByteArrayOutputStream

ByteArrayOutputStreamExample.java

package com.codeFactory;import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;/**
 * @author code.factory
 *
 */
public class ByteArrayOutputStreamExample {public static void main(String... args) {
  InputStream inputStream = null;
  try {
   inputStream = new FileInputStream(new File("files/CodeFactory.txt"));ByteArrayOutputStream result = new ByteArrayOutputStream();
   byte[] buffer = new byte[512];
   while ((inputStream.read(buffer)) != -1) {
    result.write(buffer);
   }System.out.println(result);
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
 }
}

6. Convert InputStream to String using IOUtils toString

<dependency>
     <groupId>commons-io</groupId>
     <artifactId>commons-io</artifactId>
     <version>2.6</version>
</dependency>

IOUtilsStringExample.java

package com.codeFactory;import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;import org.apache.commons.io.IOUtils;/**
 * @author code.factory
 *
 */
public class IOUtilsStringExample {public static void main(String... args) {
  InputStream inputStream = null;
  try {
   inputStream = new FileInputStream(new File("files/CodeFactory.txt"));String result = IOUtils.toString(inputStream, StandardCharsets.UTF_8);System.out.println(result);
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
 }
}

7. Convert InputStream to String using IOUtils Copy

IOUtilsCopyExample.java

package com.codeFactory;import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
import java.nio.charset.StandardCharsets;import org.apache.commons.io.IOUtils;/**
 * @author code.factory
 *
 */
public class IOUtilsCopyExample {public static void main(String... args) {
  InputStream inputStream = null;
  try {
   inputStream = new FileInputStream(new File("files/CodeFactory.txt"));StringWriter writer = new StringWriter();
   IOUtils.copy(inputStream, writer, StandardCharsets.UTF_8);
   System.out.println(writer.toString());
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
 }
}

8. Convert InputStream to String using Guava CharStreams

<dependency>
     <groupId>com.google.guava</groupId>
     <artifactId>guava</artifactId>
     <version>27.1-jre</version>
</dependency>

GuavaCharStreamsExample.java

package com.codeFactory;import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;import com.google.common.io.CharStreams;/**
 * @author code.factory
 *
 */
public class GuavaCharStreamsExample {public static void main(String... args) {
  InputStream inputStream = null;
  try {
   inputStream = new FileInputStream(new File("files/CodeFactory.txt"));String result = CharStreams.toString(new InputStreamReader(inputStream, StandardCharsets.UTF_8));System.out.println(result);
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
 }
}

9. Convert InputStream to String using Guava ByteSource

GuavaByteSourceExample.java

package com.codeFactory;import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;import com.google.common.io.ByteSource;/**
 * @author code.factory
 *
 */
public class GuavaByteSourceExample {public static void main(String... args) {
  try {
   InputStream inputStream = new FileInputStream(new File("files/CodeFactory.txt"));ByteSource byteSource = new ByteSource() {
    @Override
    public InputStream openStream() throws IOException {
     return inputStream;
    }
   };String result = byteSource.asCharSource(StandardCharsets.UTF_8).read();System.out.println(result);} catch (FileNotFoundException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
 }
}

Different Ways to Convert InputStream to String in Java | Code Factory

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