Fast I/O from terminal STDIN (user-defined FastReader class) :

import java.io.*;
import java.util.*;
import java.lang.*;
import java.math.*;

public class Main {
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }


    public static void main(String[] args) {
        FastReader s = new FastReader();
        int num = s.nextInt();
        String word = s.next();


        System.out.println("number: " + num);
        System.out.println("word: " + word);
    }
}

Fast I/O from imported file, rename "template" to filename of choice

import java.io.*;
import java.util.*;



public class Main {
    public static void main(String[] args) throws IOException {
        /* Read files, CHANGE filenames depending on problem. */
        BufferedReader f = new BufferedReader(new FileReader("template.in"));
        PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("template.out")));


        /* Add any extra variables (e.g. length, amount) here. */


        /*******************************************************/

        ArrayList < String > arrList = new ArrayList < String > (); //uses arraylist, can also use array here
        StringTokenizer st = new StringTokenizer(f.readLine()); //get first line of input file.

        while (true) { // loop using st
            while (st.hasMoreTokens()) {
                arrList.add(st.nextToken());
            }
            try {
                st = new StringTokenizer(f.readLine());
            } catch (Exception e) {
                break;
            }
        }
        /* Program begins here */
        for (String s: arrList) {
            System.out.println("index of " + s + " is " + arrList.indexOf(s));
        }

        System.out.println("size is " + arrList.size());


        /* Close files and exit program */
        out.close();
        f.close();
        System.exit(0);
    }
}

ArrayList