Instead of setting a character variable which is discarded, I assume you want to use this character to build a new String.
StringBuilder sb = new StringBuilder();
for (char ch : dna.toCharArray()) {
switch (ch) {
case 'A': sb.append('T'); break;
case 'T': sb.append('A'); break;
case 'G': sb.append('C'); break;
case 'C': sb.append('G'); break;
}
}
String dna2 = sb.toString();
1
solved I cannot process chars [closed]