Question

String input = txtInput.getText();

char[] charArray =  input.toCharArray();
char[] flipArray = null;
System.out.println(charArray.length);
for (int i = 0; i < charArray.length ; i++) {
    System.out.println(charArray[i]);

sorry if the code doesn’t make much sense.

charArray is taken from a JTextField .

So the code should do something like this.

1. Takes in a message and flip every 2 characters. That is, the 1st and 2nd characters are switched and the 3rd and 4th are switched etc;
2. For example, “You can’t read my message!” will be “oY uac’n terdam yemssga!e” after encryption;

charArray would be the Message that says “You can’t read my message!”
flipArray would be carrying the message that says “oY uac’n terdam yemssga!e”

How do I write a loop that puts it in such that…

charArray[0] = flipArray[1]
charArray[1] = flipArray[0]
charArray[2] = flipArray[3]
charArray[3] = flipArray[2]
charArray[4] = flipArray[5]
charArray[5] = flipArray[4]

The value of charArray is taken from a JTextField.

I’m doing this on NetBeans IDE 6.5.1.

Answer 1

Tomfoolery.

for( int i = 0; i < charArray.length; i+= 2 )
{
   charArray[i] = flipArray[i+1];
   charArray[i+1] = flipArray[i];
}

I’m assuming that 0,1 goes to 1,0, 2,3 to 3,2, etc.

I think this is what you really mean:

String input = ...
StringBuilder builder = new StringBuilder();

for( int i = 0; i < input.length(); i += 2 )
{
   //guard against odd text lengths
   if( i+1 < input.length() )
   {
      builder.append( input.charAt(i+1) );
   }   
   builder.append( input.charAt(i) );
}

String flippedText = builder.toString();