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Categories / Java / File Input Output

 

Use a BufferedReader and a BufferedWriter to copy a text file, inverting the case of letters in the process

import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.FileReader; import java.io.FileWriter; public class Main {   public static void main(String[] argv) throws Exception {     BufferedReader br = new BufferedReader(new FileReader("in.txt"));     BufferedWriter bw = new BufferedWriter(new FileWriter("out.txt"));     int i;     do {       i = br.read();       if (i != -1) {         if (Character.isLowerCase((char) i))           bw.write(Character.toUpperCase((char) i));         else if (Character.isUpperCase((char) i))           bw.write(Character.toLowerCase((char) i));         else           bw.write((char) i);       }     } while (i != -1);     br.close();     bw.close();   } }