I’m making an encryption program and for some reason the program completely freezes up when I press the button. I’m not sure what’s wrong because I’ve made many simple GUIs before and I’ve never encountered this is issue. Here’s the void for the button:
private void btnEncryptActionPerformed(java.awt.event.ActionEvent evt) { String origMessage = txtDInput.getText(); String encMessage = ""; String revMessage = ""; String extraStg1 = ""; String extraStg2 = ""; char tempChar; char tempExtraChar; int tempAscii; int tempExtraAscii; for (int i = origMessage.length() - 1; i >= 0; i = i--) //reverses message { revMessage = revMessage + origMessage.charAt(i); } for (int i = 0; i < revMessage.length(); i = i++) { tempChar = revMessage.charAt(i); //stores character in the tempChar variable tempAscii = (int)tempChar; //converts the character into an Ascii value tempAscii = tempAscii + 3; //adds 3 to Ascii value tempChar = (char)tempAscii; //converts Ascii value back into a character value encMessage = encMessage + tempChar; //adds the new character to the encrypted string and repeats for every character } for (int i = 0; i <= 7; i++) { tempExtraAscii = (int)Math.round(Math.random()*25+1+96); //generates a random integer between 97 and 122 tempExtraChar = (char)tempExtraAscii; //convert the random integer into a character extraStg1 = extraStg1 + tempExtraChar; //add the extra character to tempExtraStg1 } for (int i = 0; i <= 7; i++) { tempExtraAscii = (int)Math.round(Math.random()*25+1+96); //generates a random integer between 97 and 122 tempExtraChar = (char)tempExtraAscii; //convert the random integer into a character extraStg2 = extraStg2 + tempExtraChar; //add the extra character to tempExtraStg2 } encMessage = extraStg1 + encMessage + extraStg2; txtEncrypted.setText(encMessage); }
I’m a beginner at this so I’d appreciate it if the answer are as simple as possible. Thanks.
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Answer
This is the problem:
for (int i = 0; i < revMessage.length(); i = i++)
The i = i++
is a no-op – it increments i
, but then sets it back to the original value, so your loop will execute forever. Just change that to:
for (int i = 0; i < revMessage.length(); i++)
You actually have the same problem earlier:
for (int i = origMessage.length() - 1; i >= 0; i = i--)
should be
for (int i = origMessage.length() - 1; i >= 0; i--)
(As a side note, this isn’t really “encryption” in a useful way, and you shouldn’t roll your own encryption anyway, but I’ve addressed the question as asked.)