Read a file inside a Zip archive and put its content into a String in Android

Question

this is my first question, although I've already used so many tips from Stack Overflow. But for this situation I haven't found a solution yet.

Here's the situation: I have a zipped file and I want to read a specific file and put its content into a String variable, that will be returned and put into a TextView in Android. I don't want the file to be written to sdcard, I just want to perform a memory operation.

For example, inside db.zip I have a file named packed.txt, which content is "Stack á é ç". The returned String in my method shows "83 116 97 99 107 32 195 161 32 (...)" which are the UTF-8 values for the characters. I tried so far converting'em to a human-readble form, but no success. Tried InputStreamReader but I couldn't make a correct use of it. My source-code is below.

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import android.util.Log;

/** 
 * 
 * @author jon 
 */ 
public class Decompress { 
  private String _zipFile; 
  private String _location;

  public Decompress(String zipFile, String location) { 
    _zipFile = zipFile; 
    _location = location; 

    _dirChecker(""); 
  } 

  public String unzip(String desiredFile) { 

      String strUnzipped = ""; 

      try  { 
      FileInputStream fin = new FileInputStream(_zipFile); 
      ZipInputStream zin = new ZipInputStream(fin); 
      ZipEntry ze = null; 
      while ((ze = zin.getNextEntry()) != null) { 
        Log.v("Decompress", "Unzipping " + ze.getName()); 

        if(ze.isDirectory()) { 
          _dirChecker(ze.getName()); 
        } else { 

          //FileOutputStream fout = new FileOutputStream(_location + ze.getName());

            /**** Changes made below ****/  
              if (ze.getName().toString().equals(desiredFile)) {                  
                byte[] bytes = new byte[(int) ze.getSize()];
            if (zin.read(bytes, 0, bytes.length) == bytes.length) {
              strUnzipped = new String(bytes, "UTF-8");
            }
            else {
              strUnzipped = "Read error...";
            }

            /*** REMOVED
            if (ze.getName() == desiredFile) {
            for (int c = zin.read(); c != -1; c = zin.read()) {
              strUnzipped += c;
              //fout.write(c); 
            } */
          }

          zin.closeEntry(); 
          //fout.close(); 
        } 

      } 
      zin.close(); 
    } catch(Exception e) { 
      Log.e("Decompress", "unzip", e); 
    }

    return strUnzipped;

  } 

  private void _dirChecker(String dir) { 
    File f = new File(_location + dir); 

    if(!f.isDirectory()) { 
      f.mkdirs(); 
    } 
  } 
}

Answer 1

Sorry for my initial posting of this .... ran right over your paragraph stating you had tried this.

You can create the InputStreamReader with a charset of "UTF-8" which will automatically convert the input data into the correct characters for you.

while ((ze = zin.getNextEntry()) != null) { 
    Log.v("Decompress", "Unzipping " + ze.getName()); 
    if(ze.isDirectory()) { 
        _dirChecker(ze.getName()); 
    } else {
        if (ze.getName() == desiredFile) {
            byte[] bytes= new byte[ze.getSize()];
            zin.read(bytes, 0, bytes.length);
            strUnzipped= new String( bytes, "UTF-8" );
            /* Removing this as it is easier to just read all the bytes in at once
            InputStreamReader isr= new InputStreamReader(zin, "UTF-8");
            char c= 0;
            for (char c = isr.read(); c != -1; c = isr.read()) {
            strUnzipped += c;
            } 
            */
        }
        zin.closeEntry(); 
    }
} 

Please try the above and see how it works out.

Answer 2

Why not load them into a byte array and use new String(byte[]) or use the StringBuilder?

StringBuilder sb = new StringBuilder();
for (int c = zin.read(); c != -1; c = zin.read()) {
    sb.append((byte)c);
}
...
return sb.toString();