Random sentence generator

package randomPhrase;

import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Random;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class RandomPhrase {

    static Random random = new Random();

    public static void main(String[] args) throws IOException {
        JFrame frame = new JFrame("Random Phrase");
        JPanel panel = new JPanel();
        //frame.setPreferredSize(new Dimension(600,400));
        frame.add(panel);

        JButton npButton = new JButton("Noun phrase");
        panel.add(npButton);
        JButton vpButton = new JButton("Verb phrase");
        panel.add(vpButton);
        JButton sentenceButton = new JButton("Sentence (NP + VP)");
        panel.add(sentenceButton);

        frame.pack();
        frame.setVisible(true);

        npButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e)
              {
                String np = generateNP(random.nextBoolean());
                System.out.println(np);
                System.out.println();
              }
        });

        vpButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e)
              {
                String vp = generateVP(random.nextBoolean());
                System.out.println(vp);
                System.out.println();
              }
        });

        sentenceButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e)
              {
                Boolean bool = random.nextBoolean();
                String np = generateNP(bool);
                String vp = generateVP(bool);
                System.out.println(np + " " + vp);
                System.out.println();
              }
        });
    }

    public static String generateNP(boolean plural) {
        StringBuilder npsb = new StringBuilder();

        // Chance of determiner
        if(random.nextBoolean()) {
            String buffer = null;
            FileInputStream fistream = null;
            try {
                if(!plural) fistream = new FileInputStream("determiners.txt");
                else fistream = new FileInputStream("determinersplural.txt");
                BufferedReader br = new BufferedReader(new InputStreamReader(fistream));
                ArrayList<String> lines = new ArrayList<String>();
                buffer = br.readLine();
                while(buffer != null) {
                    lines.add(buffer);
                    buffer = br.readLine();
                }
                npsb.append(lines.get(random.nextInt(lines.size())));
                npsb.append(" ");
                br.close();
            } catch (FileNotFoundException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
        }

        // Chance of adjective(s)
        while(random.nextInt(3) == 0) {
            String buffer = null;
            FileInputStream fistream = null;
            try {
                fistream = new FileInputStream("adjectives.txt");
                BufferedReader br = new BufferedReader(new InputStreamReader(fistream));
                ArrayList<String> lines = new ArrayList<String>();
                buffer = br.readLine();
                while(buffer != null) {
                    lines.add(buffer);
                    buffer = br.readLine();
                }
                npsb.append(lines.get(random.nextInt(lines.size())));
                npsb.append(" ");
                br.close();
            } catch (FileNotFoundException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
        }

        // Noun
        String buffer = null;
        FileInputStream fistream = null;
        try {
            fistream = plural ? new FileInputStream("nounsplural.txt") : new FileInputStream("nouns.txt");
            BufferedReader br = new BufferedReader(new InputStreamReader(fistream));
            ArrayList<String> lines = new ArrayList<String>();
            buffer = br.readLine();
            while(buffer != null) {
                lines.add(buffer);
                buffer = br.readLine();
            }
            npsb.append(lines.get(random.nextInt(lines.size())));
            br.close();
        } catch (FileNotFoundException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

        // Chance of PP(s)
        while(random.nextInt(5) == 0) {
            npsb.append(" ");
            npsb.append(generatePP());
        }

        return npsb.toString();
    }

    public static String generatePP() {
        StringBuilder ppsb = new StringBuilder();

        // Preposition
        String buffer = null;
        try {
            FileInputStream fistream = new FileInputStream("prepositions.txt");
            BufferedReader br = new BufferedReader(new InputStreamReader(fistream));
            ArrayList<String> lines = new ArrayList<String>();
            buffer = br.readLine();
            while(buffer != null) {
                lines.add(buffer);
                buffer = br.readLine();
            }
            ppsb.append(lines.get(random.nextInt(lines.size())));
            ppsb.append(" ");
            br.close();
        } catch (FileNotFoundException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

        // Noun phrase
        ppsb.append(generateNP(random.nextBoolean()));

        return ppsb.toString();
    }

    public static String generateVP(boolean plural) {
        StringBuilder vpsb = new StringBuilder();
        String buffer = null;

        switch(random.nextInt(3)) {
        case 0: // Intransitive
            // Verb
            try {
                FileInputStream fistream = new FileInputStream("intransitives.txt");
                BufferedReader br = new BufferedReader(new InputStreamReader(fistream));
                ArrayList<String> lines = new ArrayList<String>();
                buffer = br.readLine();
                while(buffer != null) {
                    lines.add(buffer);
                    buffer = br.readLine();
                }
                vpsb.append(plural ? "are " : "is ");
                String line = lines.get(random.nextInt(lines.size()));

                // Parse line to find -ing form
                String parse[];
                String delims = "[,]+";
                parse = line.split(delims);
                if(line.indexOf(',') != -1) line = parse[1];
                else {
                    StringBuilder sb = new StringBuilder();
                    sb.append(line);
                    sb.append("ing");
                    line = sb.toString();
                }

                vpsb.append(line);
                br.close();
            } catch (FileNotFoundException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }

            break;
        case 1: // State of being + adjective
            vpsb.append(plural ? "are " : "is ");

            // Adjective
            buffer = null;
            FileInputStream fistream = null;
            try {
                fistream = new FileInputStream("adjectives.txt");
                BufferedReader br = new BufferedReader(new InputStreamReader(fistream));
                ArrayList<String> lines = new ArrayList<String>();
                buffer = br.readLine();
                while(buffer != null) {
                    lines.add(buffer);
                    buffer = br.readLine();
                }
                vpsb.append(lines.get(random.nextInt(lines.size())));
                br.close();
            } catch (FileNotFoundException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }

            break;
        case 2: // Transitive
            try {
                fistream = new FileInputStream("transitives.txt");
                BufferedReader br = new BufferedReader(new InputStreamReader(fistream));
                ArrayList<String> lines = new ArrayList<String>();
                buffer = br.readLine();
                while(buffer != null) {
                    lines.add(buffer);
                    buffer = br.readLine();
                }
                String line = lines.get(random.nextInt(lines.size()));

                // Parse line to find -s form
                String parse[];
                String delims = "[,]+";
                parse = line.split(delims);
                if(line.indexOf(',') != -1) line = parse[1];
                else {
                    StringBuilder sb = new StringBuilder();
                    sb.append(line);
                    if(!plural) sb.append("s");
                    line = sb.toString();
                }

                vpsb.append(line);
                vpsb.append(" ");
                br.close();
            } catch (FileNotFoundException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }

            // Noun phrase
            vpsb.append(generateNP(random.nextBoolean()));

            break;
        }
        return vpsb.toString();
    }
}