java characters upper and lower case - eclipse

Question

Each character should switch between upper and lower case. My issue is that I cannot get it to work properly. This is what I have so far:
oneLine = br.readLine();
while (oneLine != null){ // Until the line is not empty (will be when you reach End of file)
System.out.println (oneLine); // Print it in screen
bw.write(oneLine); // Write the line in the output file
oneLine = br.readLine(); // read the next line
}
int ch;
while ((ch = br.read()) != -1){
if (Character.isUpperCase(ch)){
Character.toLowerCase(ch);
}
bw.write(ch);
}

Answer 1

Here you go. You had a few problems:
You were never actually storing the result of the character case switch.
You needed to save the line return with each row
I broke out the case switch to make it easier to read
Here's the modified code:
public static void main(String args[]) {
String inputfileName = "input.txt"; // A file with some text in it
String outputfileName = "output.txt"; // File created by this program
String oneLine;
try {
// Open the input file
FileReader fr = new FileReader(inputfileName);
BufferedReader br = new BufferedReader(fr);
// Create the output file
FileWriter fw = new FileWriter(outputfileName);
BufferedWriter bw = new BufferedWriter(fw);
// Read the first line
oneLine = br.readLine();
while (oneLine != null) { // Until the line is not empty (will be when you reach End of file)
String switched = switchCase(oneLine); //switch case
System.out.println(oneLine + " > "+switched); // Print it in screen
bw.write(switched+"\n"); // Write the line in the output file
oneLine = br.readLine(); // read the next line
}
// Close the streams
br.close();
bw.close();
} catch (Exception e) {
System.err.println("Error: " + e.getMessage());
}
}
public static String switchCase(String string) {
String r = "";
for (char c : string.toCharArray()) {
if (Character.isUpperCase(c)) {
r += Character.toLowerCase(c);
} else {
r += Character.toUpperCase(c);
}
}
return r;
}