Thread: Basic Java Encryption

public static String encryptLine(char[] cipher, String line) {		
	char[] alphabet ={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p',
		'q','r','s','t','u','v','w','x','y','z'};
        	for (int j = 0; j < 26; j++) {
		char b = alphabet[j];
		char c = cipher[j];
		String bString = Character.toString(b);
		String cString = Character.toString(c); line = line.replace(bString, cString);  		
	        }			
	return line;
}

String line is later outputted by a PrintStream. The portion that is wrong with my program is shown above. I am trying to encrypt lines of String in a text file. The above code doesn't work because once you replace a character from cipher[], it can later be changed again during the loop. Any ideas on how I should go about doing this?