what is bufferreader in java code example

Example 1: bufferedreader java

import java.io.BufferedReader;
//
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
System.out.println(reader.readLine());

Example 2: declare bufferedreader java

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

Example 3: java bufferedreader

private static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
private static StringTokenizer st;
static String next() throws IOException {
    while (st==null||!st.hasMoreTokens()) {
        st = new StringTokenizer(br.readLine().trim());
    }
    return st.nextToken();
}
static long readLong() throws IOException {
    return Long.parseLong(next());
}
static int readInt() throws IOException {
    return Integer.parseInt(next());
}
static double readDouble() throws IOException {
    return Double.parseDouble(next());
}
static String readLine() throws IOException {
    return br.readLine().trim();
}