使用 BufferedReader 对效率有何影响？

Question

What is the difference between these 2 methods used to read characters from a file.

FIRST

FileReader fr = new FileReader( new File( "file.txt") );
int x = 0;
while( ( x = fr.read() ) != -1 ) {
    System.out.println( (char) x );
}

SECOND

BufferedReader bfr = new BufferedReader( new FileReader( new File( "file.txt") ) );
int x = 0;
while( ( x = bfr.read() ) != -1 ) {
    System.out.println( (char) x );
}

Both the codes read the characters from the file and write it on the console.

Which one of the method is more efficient and why? Or it's the same thing?

Answer 1

Consider a water tank 5km away from you. For every bucket of water you had to travel 5km. For reducing your effort, you bring a small tank and fill it once for 3-4 days. Then full your buckets from the small water tank, inside your house.

In above example the water tank 5km away is a file on the hard disk, If you use a bare reader, it is like travelling 5km for every bucket of water. So you bring a small tank(BufferedReader).

Answer 2

Thus spake the docs :

In general, each read request made of a Reader causes a corresponding read request to be made of the underlying character or byte stream. It is therefore advisable to wrap a BufferedReader around any Reader whose read() operations may be costly, such as FileReaders and InputStreamReaders.

Answer 3

Just a little addition to @cwallenpoole's answer. There is also difference in the interface. For example, in BufferedReader there is a nice method readLine(), which I use heavily.