Question

I’m making a cryptography/cryptanalysis program using java as a homework for my master. Anyway, i use a method to delete the uselless whitespaces and make the String i display to the JTextArea proper. This method is great for small texts but it gives me a StringIndexOutOfBoundsException when i use bigger texts (loaded from a .txt file). Can anyone help?
Thanks in advance.

This is the method:

public void Data(String s) {
    System.out.print("Analysis" + "\n" + s);
    jTextArea1.setText(s);
    StringBuilder buf = new StringBuilder();
    for (int i = 0; i < s.length(); i++) {
        if (!Character.isWhitespace(s.charAt(i))) {
            buf.append(s.charAt(i));
        } else if (Character.isWhitespace(s.charAt(i)) &&   !Character.isWhitespace(s.charAt(i + 1))) {
            buf.append(s.charAt(i));
        }
    }
    System.out.println(buf.toString() + "\n" + "from buf");
    jTextArea1.setText(buf.toString());
}

Answer 1

You are going up to s.length() in the for loop but accessing s.charAt(i + 1) in the second if statement. Try to only go up to s.length() - 1:

for (int i = 0; i < s.length() - 1; i++) {
    if (!Character.isWhitespace(s.charAt(i))) {
        buf.append(s.charAt(i));
    } else if (Character.isWhitespace(s.charAt(i)) &&   !Character.isWhitespace(s.charAt(i + 1))) {
        buf.append(s.charAt(i));
    }
}

And then check the last character afterwards.