RandomLineFromFile.java

import java.io.IOException;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.BufferedReader;
import java.util.Random;

public class RandomLineFromFile {

    /**
    *   Program:    RandomLineFromFile.java
    *   Purpose:    Print random line from specified file.
    *   Version:    Java 7
    *   First:      First you need to create a text file (e.g. "Phrases.txt")
    *           containing a different word or sentence on each line, which this program will use.
    *   Usage:      Compile this Java source code.  If using the JDK, type:
    *           javac RandomLineFromFile.java
    *           To Run, type
    *           java RandomLineFromFile Phrases.txt
    *           Then, if you want to make your batch file, type the same:
    *
    *           java RandomLineFromFile Phrases.txt
    *
    *           (where Phrases.txt is name of your text file - change this if necessary),
    *           type into Notepad or other text editor and save as "RandomText.bat" or similar.
    *           Run in Command Prompt. Enjoy.
    *   Creator:    Chris Clarke
    *   Created:    26.01.2015
    */

    // declare instance variable
    private static String path;

    // constructor
    public RandomLineFromFile(String filePath) {
        path = filePath;
    }

    public String[] openFile() throws IOException {
        int numberOfLines = countLines();
        if (numberOfLines==0) {
            System.out.println("No such file, or file contained zero lines of text.");
            System.exit(1);
        } // if
        String[] textData = new String[numberOfLines];
        FileReader fr = null;
        BufferedReader textReader = null;
        try {
            fr = new FileReader(path);
            textReader = new BufferedReader(fr);

            for(int i=0; i < numberOfLines; i++) {
                textData[i] = textReader.readLine();
                //System.out.println(textData[i]);  // display lines on screen
            } // for
        } catch (IOException e) {
            System.out.println("Couldn't read file!");
        } finally {
            if (textReader!=null) {
                textReader.close();
            } // if
        } // try
        return textData;
    } // openFile()

    public int countLines() throws IOException {
        int numberOfLines = 0;
        FileReader readFile = null;
        BufferedReader bf = null;
        try {
            readFile = new FileReader(path);
            bf = new BufferedReader(readFile);

            String aLine;

            while (( aLine = bf.readLine()) != null) {
                numberOfLines++;
            } // while
        } catch (IOException e) {
            System.out.println("Couldn't read file!");
        } finally {
            if (bf!=null) {
                bf.close();
            } // if
        } // try
        return numberOfLines;
    } // countLines()

    public static void main(String[] args) throws IOException {
        String filename = "MyTextFile.txt";
        if (args.length>0) {
            filename = args[0];
        } // if
        RandomLineFromFile rl = new RandomLineFromFile(filename);
        // create array of lines of text
        String[] lines = rl.openFile();
        // create random object
        Random r = new Random();
        // print a random line
        System.out.println( lines[ r.nextInt( lines.length)]);
    } // main()

} // class RandomLineFromFile