download - Files downloaded as Binary with Java are corrupted -

i have written downloader should used download text files, images. download files binaries. many of downloads work well, parts of text files , many image files corrupted. errors occur @ same files , @ same places (as long can tell when analysing text files). used code downloading:

    public file downloadfile(httpurlconnection connection) {         return writefiledatatofile(getfiledata(connection));     }           //downloads data of file , returns content string     private list<byte> getfiledata(httpurlconnection connection) {         list<byte> filedata = new arraylist<>();          try (inputstream input = connection.getinputstream()) {             byte[] filechunk = new byte[8*1024];             int bytesread;              {                 bytesread = input.read(filechunk);                 if (bytesread != -1) {                     filedata.addall(bytes.aslist(filechunk));                     filechunk = new byte[8*1024];                 }             } while (bytesread != -1);              return filedata;         } catch (ioexception e) {             system.out.println("receiving file @ " + url.tostring() + " failed");             system.exit(1);             return null; //shouldn't reached         }     }      //writes data file     private file writefiledatatofile(list<byte> filedata) {          if (!this.file.exists()) {             try {                 this.file.getparentfile().mkdirs();                 this.file.createnewfile();             } catch (ioexception e) {                 system.out.println("error while creating file @ " + file.getpath());                 system.exit(1);             }         }          try (outputstream output = new fileoutputstream(file)) {             output.write(bytes.toarray(filedata));             return file;         } catch (ioexception e) {             system.out.println("error while accessing file @ " + file.getpath());             system.exit(1);             return null;         }     } 

i suggest not pass through list of byte, since create list of byte array, array of byte, not efficient.

moreover wrongly assume chunk size (not necesseraly 8192 bytes).

why don't as:

private file writefiledatatofile(httpurlconnection connection) {     if (!this.file.exists()) {         try {             this.file.getparentfile().mkdirs();             //this.file.createnewfile(); // not needed, created @ fileoutputstream         } catch (ioexception e) {             system.out.println("error while creating file @ " + file.getpath());             //system.exit(1);             // instead throw of error or return null             throw new yourexception(message);         }     }     outputstream output = null;     inputstream input = null;     try {       output = new fileoutputstream(file):       input = connection.getinputstream();       byte[] filechunk = new byte[8*1024];       int bytesread;       while ((bytesread = input.read(filechunk )) != -1) {          output.write(filechunk , 0, bytesread);       }       return file;     } catch (ioexception e) {       system.out.println("receiving file @ " + url.tostring() + " failed");       // system.exit(1); // should avoid such exit       // instead throw of error or return null       throw new yourexception(message);     } {       if (input != null) {         try {            input.close();         } catch (execption e2) {} // ignore       }       if (output != null) {         try {            output.close();         } catch (execption e2) {} // ignore       }     } }