FileInputStream fis = null;
FileOutputStream fos = null;
try{
fis = new FileInputStream("xx.txt");
fos = new FileOutputStream("yy.txt");
int b;
while((b = fis.read()) != -1){
  fos.write(b);
}
}finally{
  try{
    if(fis != null)fis.close();
  }finally{
    if(fos != null)fos.close();
  }
}

FileInputStream fis = null;
FileOutputStream fos = null;
try{
fis = new FileInputStream("xx.txt");
fos = new FileOutputStream("yy.txt");
int b;
while((b = fis.read()) != -1){
  fos.write(b);
}
}finally{
  try{
    if(fis != null)fis.close();
  }finally{
    if(fos != null)fos.close();
  }
}