I have a byte array and I need to convert this to a image.

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Editorial Team

Asked: June 6, 20262026-06-06T22:58:40+00:00 2026-06-06T22:58:40+00:00

I have a byte array and I need to convert this to a image.

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I have a byte array and I need to convert this to a image. I’ve read this tutorial:

http://www.mkyong.com/java/how-to-convert-byte-to-bufferedimage-in-java/

This tutorial uses the BufferedImage and ImageIO which is in this import statement

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;

But I can’t find these classes anywhere. I have the JDK x64 version with the javax installed. Anybody?

My whole source code:

public class ReadImageFromFileActivity extends Activity implements OnClickListener {

Context c;
Button read;
ImageView image;
byte[] fileBytes;
byte[] image1;
byte[] image2; 


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    c = getApplicationContext(); 

    read = (Button)findViewById(R.id.file); 
    read.setOnClickListener(this);

    image = (ImageView)findViewById(R.id.image);

    image1 = new byte[ 500 * 500]; 
    image2 = new byte[ 500 * 500]; 

}



public static byte[] getBytesFromFile(Context c) throws IOException {

    File file = new File("/mnt/sdcard/LeftIndex.FIR");
    Uri URIpath = Uri.fromFile(file);

    InputStream is = c.getContentResolver().openInputStream(URIpath);

    long length = file.length();


    if (length > Integer.MAX_VALUE) {
        // File is too large
    }

    // Create the byte array to hold the data
    byte[] bytes = new byte[(int)length];

    // Read in the bytes
    int offset = 0;
    int numRead = 0;
    while (offset < bytes.length
           && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
        offset += numRead;
    }

    // Ensure all the bytes have been read in
    if (offset < bytes.length) {
        throw new IOException("Could not completely read file "+file.getName());
    }

    // Close the input stream and return bytes
    is.close();
    return bytes;
}


public void onClick(View v) {

    try {
        fileBytes = getBytesFromFile(c);
        convertByteArray(fileBytes); 

    } catch (IOException e) {
        Log.e("++++getBytesFromFile SAYS: ", "Couldn't read file!!!");

        e.printStackTrace();
    }

}


public void convertByteArray(byte[] buffer) {

     System.arraycopy(buffer, 64, image1, 0, 500 * 500);  
     System.arraycopy(buffer, 60, image2, 0, 500 * 500); 



     Bitmap bmp = BitmapFactory.decodeByteArray(image1, 0, image1.length); 
     ImageView image=new ImageView(this);
     image.setImageBitmap(bmp);



}

}

Explanation of the code

in the function getBytesFromFile I construct a new File out of a .FIR file at my SD-card. This file will be converted to a Byte array and returns the constructed byte array. This byte-array will be passed into a function called convertByteArray which will be splitted into two separate Byte arrays. From each of these two byte arrays I want to construct a Bitmap. But logcat only says that the bitmapFactory returns null.

Anybody have any solution to this?