How to convert InputStream to String in Java?

We have different ways to convert InputStream to String as given below.

Using BufferedReader and InputStreamReader
Using ByteArrayOutputStream and InputStream read
Using ByteArrayOutputStream and BufferedInputStream
Using Scanner class
Using Apache Commons IOUtils toString
Using Java 8 Streams

1) Using BufferedReader and InputStreamReader

Create BufferedReader object from InputStream using InputStreamReader. It will read the content line by line from BufferedReader and append the lines to StringBuilder. Once done, convert StringBuilder to String using toString method.

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class InputStreamToString {
  public static void main(String[] args) {
InputStream is = null;
try{
File f=new File("E:/java/text.txt");
System.out.println("File exist "+f.exists());
//create InputStream from file
is = new FileInputStream(f);
String str = convertInputStreamToString(is);
   System.out.println(str);
}catch(IOException ioe){
ioe.printStackTrace();
}finally{
try{
if(is != null)
is.close();
}catch(Exception e){ e.printStackTrace(); }
}
}

/*
* Method to convert InputStream to String
*/
private static String convertInputStreamToString(InputStream is) {
  BufferedReader br = null;
StringBuilder sbContent = new StringBuilder();
try{
/*
* Create BufferedReader from InputStreamReader
*/
br = new BufferedReader(new InputStreamReader(is));
/*
* read line by line and append content to
* StringBuilder
*/
String strLine = null;
boolean isFirstLine = true;
while( (strLine = br.readLine()) != null){
if(isFirstLine)
sbContent.append(strLine);
else
sbContent.append("\n").append(strLine);
/*
* Flag to make sure we don't append new line
* before the first line.
*/
isFirstLine = false;
}
}catch(IOException ioe){
ioe.printStackTrace();
}finally{
try{
if(br != null)
br.close();
}catch(Exception e){ e.printStackTrace(); }
}
  //convert StringBuilder to String and return
return sbContent.toString();
}
}

Output

Welcome to Java File to String
This Example shows Convert to String

2) Using ByteArrayOutputStream and InputStream read

private static String convertInputStreamToString(InputStream is) {

String strResult = null;

//create ByteArrayOutputStream
ByteArrayOutputStream bos = new ByteArrayOutputStream();

try{

//create buffer to hold bytes read from stream
byte[] buffer = new byte[1024];

/*
* Read bytes from InputStream to buffer
* until there are no more bytes
*/
int size;
while((size = is.read(buffer)) != -1){

//write buffer to the ByteArrayOutputStream
bos.write(buffer, 0, size);
}

//convert ByteArrayOutputStream to String using UTF-8 Character Set
strResult = bos.toString( StandardCharsets.UTF_8.name());

}catch(IOException ioe){
ioe.printStackTrace();
}finally{
try{
if(bos != null)
bos.close();
}catch(Exception e){ e.printStackTrace(); }
}

return strResult;
}

3) Using ByteArrayOutputStream and BufferedInputStream

private static String convertInputStreamToString(InputStream is) {

String strResult = null;

ByteArrayOutputStream bos = null;
BufferedInputStream bis = null;

try{

//create ByteArrayOutputStream
bos = new ByteArrayOutputStream();

//create BufferedInputStream from InputStream
bis = new BufferedInputStream(is);

int byteValue;
while( (byteValue = bis.read()) != -1 ){
bos.write(byteValue);
}

//convert ByteArrayOutputStream to String using UTF-8 Character Set
strResult = bos.toString( StandardCharsets.UTF_8.name());

}catch(IOException ioe){
ioe.printStackTrace();
}finally{
try{
if(bos != null)
bos.close();
}catch(Exception e){ e.printStackTrace(); }
try{
if(bis != null)
bis.close();
}catch(Exception e){ e.printStackTrace(); }
}

return strResult;
}

4) Using Scanner

private static String convertInputStreamToString(InputStream is) {

String strResult = null;

Scanner scanner = null;

try{

//create scanner from InputStream
scanner = new Scanner(is);

//set scanner delimiter as beginning of the content
scanner.useDelimiter("\\A");

//get the token - this will return whole content as single token
if( scanner.hasNext() )
strResult = scanner.next();

}catch(Exception e){
e.printStackTrace();
}finally{
try{
if(scanner != null)
scanner.close();
}catch(Exception e){ e.printStackTrace(); }
}

return strResult;
}

5) Using Apache Commons IOUtils toString

private static String convertInputStreamToString(InputStream is) throws IOException {

String strResult = IOUtils.toString(is, Charset.forName("UTF-8"));

return strResult;

}

6) Using Java 8 Streams

private static String convertInputStreamToString(InputStream is) throws IOException {

//Create BufferedReader from the input stream

BufferedReader br = new BufferedReader(new InputStreamReader(is));

//read lines separated by new line and join them again using \n

String strResult = br.lines().collect(Collectors.joining("\n"));

return null;

}

How to convert InputStream to String in Java?

Using BufferedReader and InputStreamReader

Using ByteArrayOutputStream and InputStream read

Using ByteArrayOutputStream and BufferedInputStream

Using Scanner class

Using Apache Commons IOUtils toString

Using Java 8 Streams

2) Using ByteArrayOutputStream and InputStream read

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