Question

My program is receiving an integer array from a browser application that’s interpreted as UTF-8 (example in code). I can echo my resulting string (“theString” shown in the code below) back to the browser and everything’s fine. But it’s not fine in the Java program. The input string is “Hällo”. But it prints out from the Java program as “Hõllo”.

import java.io.*;
import java.nio.charset.*;

public class TestCode {
   public static void main (String[] args) throws IOException {

      // H : 72
      // ä : 195 164
      // l : 108
      // o : 111
      // the following is the input sent from browser representing String = "Hällo"
      int[] utf8Array = {72, 195, 164, 108, 108, 111};

      String notYet = new String(utf8Array, 0, utf8Array.length);
      String theString = new String(notYet.getBytes(), Charset.forName("UTF-8"));

      System.out.println(theString);
   }
}

Answer 1

This will do the trick:

int[] utf8Array = {72, 195, 164, 108, 108, 111};
byte[] bytes = new byte[utf8Array.length];
for (int i = 0; i < utf8Array.length; ++i) {
    bytes[i] = (byte) utf8Array[i];
}
String theString = new String(bytes, Charset.forName("UTF-8"));

The problem with passing int[] directly is that the String class interprets every int as a separate char, while after converting to byte[] String treats input as raw bytes and understands that 195, 164 is actually is a single character consisting of two bytes rather than two characters.

UPDATE: Answering your comment, unfortunately, Java is that verbose. Compare it to Scala:

val ints = Array(72, 195, 164, 108, 108, 111)
println(new String(ints map (_.toByte), "UTF-8"))

Once again the difference between int and byte is not just the compiler being picky, they really mean different things when it comes to UTF-8 encoding.