CODEWITHSUNDEEP
javafileinputstream
bhushan23
bhushan23

Reputation: 501

How to convert FileInputStream into string in java?

In my java project, I'm passing FileInputStream to a function, I need to convert (typecast FileInputStream to string), How to do it.??

public static void checkfor(FileInputStream fis) {
   String a=new String;
   a=fis         //how to do convert fileInputStream into string
   print string here
}

Upvotes: 31

Views: 105378

Answers (6)

atr
atr

Reputation: 714

Using Apache commons IOUtils function

import org.apache.commons.io.IOUtils;

InputStream inStream = new FileInputStream("filename.txt");
String body = IOUtils.toString(inStream, StandardCharsets.UTF_8.name());

Upvotes: 16

Mohammad Zuha Khalid
Mohammad Zuha Khalid

Reputation: 87

Use following code ---->

try {
    FileInputStream fis=new FileInputStream("filename.txt");
    int i=0;    
    while((i = fis.read()) !=-1 ) {  // to reach until the laste bytecode -1
        System.out.print((char)i);   /* For converting each bytecode into character */ 
    }
    fis.close();
} catch(Exception ex) {
    System.out.println(ex); 
}

Upvotes: 1

Andrew
Andrew

Reputation: 1

From an answer I edited here:

static String convertStreamToString(java.io.InputStream is) {
    if (is == null) {
        return "";
    }

    java.util.Scanner s = new java.util.Scanner(is);
    s.useDelimiter("\\A");

    String streamString = s.hasNext() ? s.next() : "";

    s.close();

    return streamString;
}

This avoids all errors and works well.

Upvotes: 1

Arsen Alexanyan
Arsen Alexanyan

Reputation: 3141

You can't directly convert it to string. You should implement something like this Add this code to your method

    //Commented this out because this is not the efficient way to achieve that
    //StringBuilder builder = new StringBuilder();
    //int ch;
    //while((ch = fis.read()) != -1){
    //  builder.append((char)ch);
    //}
    //          
    //System.out.println(builder.toString());

Use Aubin's solution:

public static String getFileContent(
   FileInputStream fis,
   String          encoding ) throws IOException
 {
   try( BufferedReader br =
           new BufferedReader( new InputStreamReader(fis, encoding )))
   {
      StringBuilder sb = new StringBuilder();
      String line;
      while(( line = br.readLine()) != null ) {
         sb.append( line );
         sb.append( '\n' );
      }
      return sb.toString();
   }
}

Upvotes: 31

Aubin
Aubin

Reputation: 14853

public static String getFileContent(
   FileInputStream fis,
   String          encoding ) throws IOException
 {
   try( BufferedReader br =
           new BufferedReader( new InputStreamReader(fis, encoding )))
   {
      StringBuilder sb = new StringBuilder();
      String line;
      while(( line = br.readLine()) != null ) {
         sb.append( line );
         sb.append( '\n' );
      }
      return sb.toString();
   }
}

Upvotes: 24

AgilePro
AgilePro

Reputation: 5598

Don't make the mistake of relying upon or needlessly converting/losing endline characters. Do it character by character. Don't forget to use the proper character encoding to interpres the stream.

public String getFileContent( FileInputStream fis ) {
    StringBuilder sb = new StringBuilder();
    Reader r = new InputStreamReader(fis, "UTF-8");  //or whatever encoding
    int ch = r.read();
    while(ch >= 0) {
        sb.append(ch);
        ch = r.read();
    }
    return sb.toString();
}

If you want to make this a little more efficient, you can use arrays of characters instead, but to be honest, looping over the characters can be still quite fast.

public String getFileContent( FileInputStream fis ) {
    StringBuilder sb = new StringBuilder();
    Reader r = new InputStreamReader(fis, "UTF-8");  //or whatever encoding
    char[] buf = new char[1024];
    int amt = r.read(buf);
    while(amt > 0) {
        sb.append(buf, 0, amt);
        amt = r.read(buf);
    }
    return sb.toString();
}

Upvotes: 3

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