write a small andriod app for converting letters between uppercase and lowercase

1. import java.io.*;
class BufferTest {
public static void main(String args[]){
//creat stream
FileReader fileReader = null;
BufferedReader bufferedReader = null;
FileWriter fileWriter = null;
BufferedWriter bufferedWriter = null;
String line = null;
try{
//acquire origin file address
fileReader = new FileReader("f:/excise/Stream/zzz.txt");
//output path of generated file
fileWriter = new FileWriter("f:/excise/Stream/aaa.txt");
//write buffer stream
bufferedReader = new BufferedReader(fileReader);
//write buffer stream
bufferedWriter = new BufferedWriter(fileWriter);
//read data iteratively
while(true){
//read one line data
line = bufferedReader.readLine();
if(line == null){
break;
}
String str = line.toUpperCase();//to uppercase
//String str = line.toLowerCase(); to lowercase
//output buffer stream
bufferedWriter.write(str);
//change line
bufferedWriter.newLine();
}
}
catch(Exception e){
System.out.println(e);
}finally{
try{
//close stream
fileReader.close();
bufferedReader.close();
bufferedWriter.close();
fileWriter.close();
}
catch(Exception e){
System.out.println(e);
}
}
}
}