Java Servlet program to separate Image Strings using Array or Array List

Question

In my java servlet program i am getting images from android application.I want to encode again decode image. If i got two images from android: [abc,def].It is decoded using MyHelper.decodeImage1(a). Now problem comes in next step. I want to encode decoded image again. Yes it do encoding. But result is in a single string abcdef. How can i separate two images to send it back to android? How should i manage loop or array in loop. I have tried alot but can't differentiate abc and def. Please help

 String imageString=request.getParameter("image");
 // image comees in format [abc,def,efg... and son on]

        imageString=imageString.replace("[", "");
        imageString=imageString.replace("]", "");
        imageString=imageString.replace(" " , "");

        String[] r = imageString.split(",");

for(int i=0; i<r.length;i++){

                String a=r[i];
                System.out.println("In loop = "+i);

                byte[] imageByteArray = MyHelper.decodeImage1(a);

            String encodedimageByteArray=Base64.encodeBytes(imageByteArray) ;
            ArrayList<String> StringImages =  new ArrayList<String>();
            StringImages.add(encodedimageByteArray);
            response.getWriter().write(encodedimageByteArray);


                }

Well what do you want the response to look like? You'll need to work out some separator to insert between each pair of images. (It's not clear why you're creating a list of images on each iteration of the loop, by the way.) — Jon Skeet
– Jon Skeet, Commented Mar 4, 2014 at 7:05
or abc,def. How can i separate abcdef. Two strings abc and def concatenate in a single string abcdef — user3118495
– user3118495, Commented Mar 4, 2014 at 7:08
Well you call write to write a string... so you can write whatever you want. For example, at the start of the loop: if (i != 0) { response.getWriter.write(",")) }. If you want to put it in square brackets you'll need a little bit more work, but fundamentally you're just writing strings to a writer. — Jon Skeet
– Jon Skeet, Commented Mar 4, 2014 at 7:12

Jon Skeet · Accepted Answer · 2014-03-04 07:15:31Z

0

All you need to do is call write appropriately with the text you want to write. For example:

Writer writer = response.getWriter();
writer.write("[");
for (int i = 0; i < r.length; i++) {
     if (i != 0) {
         writer.write(","); // Separate this item from the previous one
     }
     byte[] bytes = MyHelper.decodeImage1(r[i]);
     String base64 = Base64.encodeBytes(bytes);
     writer.write(base64);
}
writer.write("]");

answered Mar 4, 2014 at 7:15

Jon Skeet

1.5m892 gold badges9.3k silver badges9.3k bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

user3118495 Over a year ago

no need for square brackets...abc,def is ok. But i am not getting it. , should be added in encodedimageByteArray string, after iterating each image.

user3118495 Over a year ago

i want to use only 1 writer.write(base64). base64 string should be [abc,def] or abc,def

Jon Skeet Over a year ago

@user3118495: You can't do that, because , isn't part of base64 encoding. [abc,def] simply isn't a valid base64 string. Why would you only want to call write once?

user3118495 Over a year ago

@yes once only please. I can make my string abc,def...and so on.then i write the string to app.

Jon Skeet Over a year ago

@user3118495: But that's not a base64 string. "Yes" doesn't answer my question about why you don't want to call write more than once. What do you think will go wrong? Yes, you could create a StringBuilder, build everything in that and then call write(builder.toString()) but it's pointless.

Collectives™ on Stack Overflow

Java Servlet program to separate Image Strings using Array or Array List

1 Answer 1

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related