I wrote a Java FX application that translates binary to and from String and numbers in Java. Whenever the program is translating large amounts of text to binary it takes a very long time, and leaves the application unresponsive. Could a more efficient algorithm be used to speed up the process?

    // Turns binary into text. 
private void binaryToText() throws BinaryFormatException
    if (input.toString().length() % 8 != 0)
        throw new BinaryFormatException("Binary must be a multiple of 8");

    String input = this.input.toString();
    String _byte = "", textResult = "";

    for (int i = 1 ; i <= input.length() ; i++) {
        _byte += input.charAt(i-1);
        if (i % 8 == 0) {
            int charCode = Integer.parseInt(_byte, 2);
            textResult += (char) charCode;
            _byte = "";

    this.output = textResult;

// Turns text into binary. 
private void textToBinary()
    String binResult = "";
    final String fourBitPrepend = "0000";
    final String twoBitPrepend = "00";
    final String bitPrepend = "0";
    byte[] charCodes = input.toString().getBytes();

    for(byte ch : charCodes) {
        String binary = Integer.toBinaryString(ch);
        switch(binary.length()) {
            case 4 : binResult += fourBitPrepend + binary; break;
            case 6 : binResult += twoBitPrepend + binary; break;
            case 7 : binResult += bitPrepend + binary; break;
            default : binResult += binary;

    this.output = binResult;
  • \$\begingroup\$ The algorithmic problem causing a very long time to be taken is not visible in the in the code presented: appending single chars to a String causes a new StringBuilder to be instantiated, initialised with the String's contents, and extended with the char. Then, a new StringBuilder to be instantiated and initialised with the String's contents - in a loop, consuming noticeable time in no time: use StringBuilder & append(). (Repeated input.toString() doesn't help.) \$\endgroup\$
    – greybeard
    Commented Jul 10, 2016 at 5:08
  • \$\begingroup\$ (The "String +-issue" aside, your binaryToText() looks even weirder than the textToBinary(): please disclose the type of data member input. If this is an assignment in learning Java, please tell to help avoid spoiling a learning experience.) \$\endgroup\$
    – greybeard
    Commented Jul 10, 2016 at 5:43

2 Answers 2


Sure, you may speed up your code execution. But the core problem remains: Inresponsive UI executing a long running task.

If you expect the user wait for completion a long running task you should consider UI supported synchronized mechanisms to adress it.

Asynchronous execution is mentioned here:


The idea is: Execute your code in a separate thread and synchronize results by publishing them through the Java FX thread.


JavaFX Nodes runs on a separate UI Thread and this Thread should never be used other than to update the UI Components.. Always use a separate Thread to do the operations not related to UI. see this PrimeFinder Example.

And here is my version of your binaryToText

private static String binaryToText(String input) {

    if (input.length() % 8 != 0) {
        throw new IllegalArgumentException("input must be a multiple of 8");

    StringBuilder result = new StringBuilder();

    for (int i = 0; i <input.length(); i+=8) {
            int charCode = Integer.parseInt(input.substring(i,i+8), 2);
            result.append((char) charCode);

    return result.toString();
  • \$\begingroup\$ Make it a habit to provide a size to constructors if you got a good guess (final byte[] textBytes = input.getBytes(); final StringBuilder binary = new StringBuilder(textBytes.length*8);. (The whole idea of implementing something without a specification is fallacious - and the binaryToText(String input) ended up doing something dissimilar. Going "bare metal" for textToBinary() would eliminate leading-zero-contortions but for the funny case 4/6/7 from the question.) \$\endgroup\$
    – greybeard
    Commented Aug 4, 2016 at 6:17
  • \$\begingroup\$ @greybeard u caught me. i just removed the code for now till i got it with proper specification \$\endgroup\$
    – Mak
    Commented Aug 4, 2016 at 8:27

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