We Keep Coding

How to read the file and save into the hashmap, then save the first element as the key and the rest in a set?

I am reading a file with a disease name and its remedies. Therefore, i want to save the name as key and remedies in a set as the value. How can i reach that? It seems there is some problems in my code.
public static HashMap<String,Set<String>> disease = new HashMap <> ();
public static void main(String[] args) {
Scanner fin = null;
try {
fin = new Scanner (new File ("diseases.txt"));
while (fin.hasNextLine()) {
HashSet <String> remedies = null;
String [] parts = fin.nextLine().split(",");
int i = 1;
while (fin.hasNext()) {
remedies.add(parts[i].trim());
i++;
}
disease.put(parts[0],remedies);
}
fin.close();
}catch(Exception e) {
System.out.println("Error: " + e.getMessage());
}
finally {
try {fin.close();} catch(Exception e) {}
}
Set <String> result = disease.get("thrombosis");
display(result);
public static <T> void display (Set<T> items) {
if (items == null)
return;
int LEN = 80;
String line = "[";
for (T item:items) {
line+= item.toString() + ",";
if (line.length()> LEN) {
line = "";
}
}
System.out.println(line + "]");
}
here is my code
cancer,pain,swelling,bleeding,weight loss
gout,pain,swelling
hepatitis A,discoloration,malaise,tiredness
thrombosis,high heart rate
diabetes,frequent urination
and here is what the txt contains.

In your code , you haven't initialized the remedies HashSet(thats why it is throwing NullPointerException at line number 14).
and second issue is : i is getting incremented by 1 and you are not checking with size of your pats array ( i > parts.length) .
I edited your code :
Scanner fin = null;
try {
fin = new Scanner(new File("diseases.txt"));
while (fin.hasNextLine()) {
HashSet<String> remedies = new HashSet<String>();
String[] parts = fin.nextLine().split(",");
int i = 1;
while (fin.hasNext()&&parts.length>i) {
remedies.add(parts[i].trim());
i++;
}
disease.put(parts[0], remedies);
}

import java.util.HashMap;
import java.util.HashSet;
import java.util.Scanner;
import java.io.File;
import java.util.Set;
public class Solution {
public static HashMap<String, Set<String>> disease = new HashMap<>();
public static void main(String[] args) {
Scanner fin = null;
try {
fin = new Scanner (new File("diseases.txt"));
while (fin.hasNextLine()) {
HashSet <String> remedies = new HashSet<>();
String [] parts = fin.nextLine().split(",");
for (int i=1; i < parts.length; i++) {
remedies.add(parts[i].trim());
}
disease.put(parts[0],remedies);
}
fin.close();
}catch(Exception e) {
System.out.println("Error: " + e.getMessage());
}
finally {
try {fin.close();} catch(Exception e) {}
}
Set <String> result = disease.get("thrombosis");
display(result);
}
public static <T> void display(Set<T> items) {
if (items == null)
return;
int LEN = 80;
String line = "[";
for (T item : items) {
line += item.toString() + ",";
if (line.length() > LEN) {
line = "";
}
}
System.out.println(line + "]");
}
}
Here is full working code. As suggested by #Pratik that you forget to initialize HashSet that's why NullPointerException error was coming.

You have a few issues here:
no need for inner while loop (while (fin.hasNext()) {) - instead use `for(int i=1; i
HashSet <String> remedies = null; - this means the set is not initialized and we cannot put items in it - nede to change to: HashSet<String> remedies = new HashSet<>();
It is better practice to close() the file in the finally part
The 'display' method will delete the line (if it is longer than 80 characters) before printing it.
it is better to use StringBuilder when appending strings
So the corrected code would be:
import java.io.File;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;
public class TestSOCode {
public static HashMap<String,Set<String>> disease = new HashMap<>();
private static int LINE_LENGTH = 80;
public static void main(String[] args) {
Scanner fin = null;
try {
fin = new Scanner(new File("diseases.txt"));
while (fin.hasNextLine()) {
HashSet<String> remedies = new HashSet<>();
String[] parts = fin.nextLine().split(",");
disease.put(parts[0], remedies);
for (int i = 1; i < parts.length; i++) {
remedies.add(parts[i].trim());
}
}
} catch (Exception e) {
System.out.println("Error: " + e.getMessage());
} finally {
try {
fin.close();
} catch (Exception e) {
System.out.println("Error when closing file: " + e.getMessage());
}
}
Set<String> result = disease.get("thrombosis");
display(result);
}
public static <T> void display (Set<T> items) {
if (items == null)
return;
StringBuilder line = new StringBuilder("[");
int currentLength = 1; // start from 1 because of the '[' char
for (T item:items) {
String itemStr = item.toString();
line.append(itemStr).append(",");
currentLength += itemStr.length() + 1; // itemStr length plus the ',' char
if (currentLength >= LINE_LENGTH) {
line.append("\n");
currentLength = 0;
}
}
// replace last ',' with ']'
line.replace(line.length() - 1, line.length(), "]");
System.out.println(line.toString());
}
}

No Line Found Error (java.util.NoSuchElementException)

I'm trying to handle multiple exceptions in my code, while using the Scanner to let the user enter a new path if the current one is incorrect, however I keep getting the same error, "No Line Found". Any help would be appreciated. The problem is occurring in the catch blocks at "path = sc.nextLine()".
public class Deck {
private static ArrayList<Card> monsters = new ArrayList<Card>();
private static ArrayList<Card> spells = new ArrayList<Card>();
private ArrayList<Card> deck = new ArrayList<Card>();
private static String monstersPath = "Database-Monster.csv";
private static String spellsPath = "Database-Spells.csv";
// private static Board board;
public Deck() throws IOException, UnknownCardTypeException,
UnknownSpellCardException, MissingFieldException,
EmptyFieldException {
if (monsters== null) {
monsters = loadCardsFromFile(monstersPath);
}
if (spells == null) {
spells = loadCardsFromFile(spellsPath);
}
// shuffleDeck();
buildDeck(monsters, spells);
shuffleDeck();
}
/*
* public static Board getBoard() { return board; }
*
* public static void setBoard(Board board) { Deck.board = board; }
*/
public ArrayList<Card> loadCardsFromFile(String path) throws IOException,
UnknownCardTypeException, UnknownSpellCardException,
MissingFieldException, EmptyFieldException {
Scanner sc = new Scanner(System.in);
int trials = 3;
String currentLine = null;
//String newPath = "";
for (int i = 0; i <=trials ; i++) {
try {
FileReader fileReader = new FileReader(path);
BufferedReader br = new BufferedReader(fileReader);
ArrayList<Card> temp = new ArrayList<Card>();
int sourceLineNumber = 1; // Source line
while ((currentLine = br.readLine()) != null) {
String[] mOrS = new String[6]; // Monsters or Spells
mOrS = currentLine.split(",");
int sourceFieldNumber = 0;
while (sourceFieldNumber < mOrS.length) {
if (mOrS[sourceFieldNumber].equals("")
|| mOrS[sourceFieldNumber].equals(" ")) {
throw new EmptyFieldException(path,
sourceLineNumber, sourceFieldNumber + 1); // Depends
// on
// the
// Splitted
// String
// array,
// loop
// on
// every
// field
// and
// check
}
sourceFieldNumber++;
}
if (mOrS[0].equals("Monster")) {
if (mOrS.length == 6) {
int attack = (int) (Integer.parseInt(mOrS[3]));
int defense = (int) (Integer.parseInt(mOrS[4]));
int level = (int) (Integer.parseInt(mOrS[5]));
MonsterCard monster = new MonsterCard(mOrS[1],
mOrS[2], level, attack, defense);
temp.add(monster);
} else {
throw new MissingFieldException(path,
sourceLineNumber); // Depends on the amount
// of fields in the
// String array, Monster
// should have 6, Type
// and 5 attributes.
}
} else if (mOrS[0].equals("Spell")) {
if (mOrS.length != 3) {
throw new MissingFieldException(path,
sourceLineNumber); // Depends on the amount
// of fields in the
// String Array, Spells
// should have 3, Type
// and 2 attributes
}
if (mOrS[1].equals("Card Destruction")) {
CardDestruction cardDestruction = new CardDestruction(
mOrS[1], mOrS[2]);
temp.add(cardDestruction);
} else if (mOrS[1].equals("Change Of Heart")) {
ChangeOfHeart changeOfHeart = new ChangeOfHeart(
mOrS[1], mOrS[2]);
temp.add(changeOfHeart);
} else if (mOrS[1].equals("Dark Hole")) {
DarkHole darkHole = new DarkHole(mOrS[1], mOrS[2]);
temp.add(darkHole);
} else if (mOrS[1].equals("Graceful Dice")) {
GracefulDice gracefulDice = new GracefulDice(
mOrS[1], mOrS[2]);
temp.add(gracefulDice);
} else if (mOrS[1].equals("Harpie's Feather Duster")) {
HarpieFeatherDuster harpieFeatherDuster = new HarpieFeatherDuster(
mOrS[1], mOrS[2]);
temp.add(harpieFeatherDuster);
} else if (mOrS[1].equals("Heavy Storm")) {
HeavyStorm heavyStorm = new HeavyStorm(mOrS[1],
mOrS[2]);
temp.add(heavyStorm);
} else if (mOrS[1].equals("Mage Power")) {
MagePower magePower = new MagePower(mOrS[1],
mOrS[2]);
temp.add(magePower);
} else if (mOrS[1].equals("Monster Reborn")) {
MonsterReborn monsterReborn = new MonsterReborn(
mOrS[1], mOrS[2]);
temp.add(monsterReborn);
} else if (mOrS[1].equals("Pot of Greed")) {
PotOfGreed potOfGreed = new PotOfGreed(mOrS[1],
mOrS[2]);
temp.add(potOfGreed);
} else if (mOrS[1].equals("Raigeki")) {
Raigeki raigeki = new Raigeki(mOrS[1], mOrS[2]);
temp.add(raigeki);
} else {
throw new UnknownSpellCardException(path,
sourceLineNumber, mOrS[1]); // We have 10
// spells, if
// there is an
// unknown one
// we throw the
// exception
}
} // else of Spell code
else {
throw new UnknownCardTypeException(path,
sourceLineNumber, mOrS[0]); // We have two
// types, Monster
// and Spell.
}
sourceLineNumber++;
}// While loop close
br.close();
return temp;
}// try Close
catch (FileNotFoundException exception) {
if (i == 3) {
throw exception;
}
System.out
.println("The file was not found, Please enter a correct path:");
path = sc.nextLine();
//path = newPath;
} catch (MissingFieldException exception) {
if (i == 3) {
throw exception;
}
System.out.print("The file path: " + exception.getSourceFile()
+ "At Line" + exception.getSourceLine()
+ "Contians a missing Field");
System.out.print("Enter New Path");
path = sc.nextLine();
//path = newPath;
} catch (EmptyFieldException exception) {
if (i == 3) {
throw exception;
}
System.out.println("The file path" + exception.getSourceFile()
+ "At Line" + exception.getSourceLine() + "At field"
+ exception.getSourceField()
+ "Contains an Empty Field");
System.out.println("Enter New Path");
path = sc.nextLine();
//path = newPath;
} catch (UnknownCardTypeException exception) {
if (i == 3) {
throw exception;
}
System.out.println("The file path:" + exception.getSourceFile()
+ "At Line" + exception.getSourceLine()
+ "Contains an Unknown Type"
+ exception.getUnknownType());
System.out.println("Enter New Path");
path = sc.nextLine();
//path = newPath;
} catch (UnknownSpellCardException exception) {
if (i == 3) {
throw exception;
}
System.out.println("The file Path" + exception.getSourceFile()
+ "At Line" + exception.getSourceLine()
+ "Contains an Unknown Spell"
+ exception.getUnknownSpell());
System.out.println("Enter New Path");
path = sc.nextLine();
//path = newPath;
}
} // For loop close
ArrayList<Card> noHope = null;
return noHope;
}// Method Close

You should use hasNext() before assigning path = sc.nextLine();
Something like :-
if (sc.hasNext()){
path = sc.nextLine();
}
else{
//print something else.
}
next
public String next() Finds and returns the next complete token from
this scanner. A complete token is preceded and followed by input that
matches the delimiter pattern. This method may block while waiting for
input to scan, even if a previous invocation of hasNext() returned
true. Specified by: next in interface Iterator Returns: the
next token Throws: NoSuchElementException - if no more tokens are
available IllegalStateException - if this scanner is closed See Also:
Iterator

failed to pop the top of stack

I try to create a stack that will be interactive to the user. It will give a choice to pop a data one by one or all of the data. My problem is, when I try to pop just a data, it gives me empty string.
Here's my code :
package Tugas;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.EmptyStackException;
import java.util.Scanner;
import java.util.Stack;
import java.util.logging.Level;
import java.util.logging.Logger;
public class myStack {
private static Stack<Integer> stack;
private static int size;
public static void main(String[] args) {
System.out.println("Enter amount numbers : ");
size = inputData();
createStack(size);
readData();
Scanner scanner = new Scanner(System.in);
System.out.println("Take it All (y) or one by one (n)");
String input = scanner.next();
if (input.equals("y")) {
writeData();
} else {
popData();
writeData();
String confirm;
Scanner scanner2 = new Scanner(System.in);
System.out.println("Take again ? ");
confirm = scanner2.next();
if (confirm.equals("y")) {
popData();
writeData();
}
}
}
private static void createStack(int size) {
stack = new Stack<>();
}
private static void writeData() {
int dataStack;
System.out.println(" The contains of data: ");
for (int i = 0; i < size; i++) {
try {
dataStack = stack.pop();
System.out.println("Value of stack at " + (i + 1) + " : " + dataStack);
} catch (EmptyStackException e) {
}
}
}
private static void readData() {
int data;
System.out.println("===== all data =====");
for (int i = 0; i < size; i++) {
System.out.print("The data at : " + (i + 1) + " : ");
data = inputData();
stack.push(data);
}
}
private static void popData() {
int dataStack;
System.out.println("=== Pop a data : ===");
dataStack = stack.pop();
}
private static Integer inputData() {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String input = null;
try {
input = br.readLine();
} catch (IOException ex) {
Logger.getLogger(Tumpukan.class.getName()).log(Level.SEVERE, null, ex);
}
int data = Integer.parseInt(input);
return data;
}
}
Thanks for the help ...

You pop data twice :
Once in :
popData();
And then in a loop in :
writeData();
This means writeData will be one element short, since it was already popped by popData.

Scanner from file doesn't seem to be reading file

I'm doing a Phone Directory project and we have to read from a directory file telnos.txt
I'm using a Scanner to load the data from the file telnos.txt, using a loadData method from a previous question I asked here on StackOverflow.
I noticed attempts to find a user always returned Not Found, so I added a few System.out.printlns in the methods to help me see what was going on. It looks like the scanner isn't reading anything from the file. Weirdly, it is printing the name of the file as what should be the first line read, which makes me think I've missed something very very simple here.
Console
run:
telnos.txt
null
loadData tested successfully
Please enter a name to look up: John
-1
Not found
BUILD SUCCESSFUL (total time: 6 seconds)
ArrayPhoneDirectory.java
import java.util.*;
import java.io.*;
public class ArrayPhoneDirectory implements PhoneDirectory {
private static final int INIT_CAPACITY = 100;
private int capacity = INIT_CAPACITY;
// holds telno of directory entries
private int size = 0;
// Array to contain directory entries
private DirectoryEntry[] theDirectory = new DirectoryEntry[capacity];
// Holds name of data file
private final String sourceName = "telnos.txt";
File telnos = new File(sourceName);
// Flag to indicate whether directory was modified since it was last loaded or saved
private boolean modified = false;
// add method stubs as specified in interface to compile
public void loadData(String sourceName) {
Scanner read = new Scanner("telnos.txt").useDelimiter("\\Z");
int i = 1;
String name = null;
String telno = null;
while (read.hasNextLine()) {
if (i % 2 != 0)
name = read.nextLine();
else
telno = read.nextLine();
add(name, telno);
i++;
}
}
public String lookUpEntry(String name) {
int i = find(name);
String a = null;
if (i >= 0) {
a = name + (" is at position " + i + " in the directory");
} else {
a = ("Not found");
}
return a;
}
public String addChangeEntry(String name, String telno) {
for (DirectoryEntry i : theDirectory) {
if (i.getName().equals(name)) {
i.setNumber(telno);
} else {
add(name, telno);
}
}
return null;
}
public String removeEntry(String name) {
for (DirectoryEntry i : theDirectory) {
if (i.getName().equals(name)) {
i.setName(null);
i.setNumber(null);
}
}
return null;
}
public void save() {
PrintWriter writer = null;
// writer = new PrintWriter(FileWriter(sourceName));
}
public String format() {
String a;
a = null;
for (DirectoryEntry i : theDirectory) {
String b;
b = i.getName() + "/n";
String c;
c = i.getNumber() + "/n";
a = a + b + c;
}
return a;
}
// add private methods
// Adds a new entry with the given name and telno to the array of
// directory entries
private void add(String name, String telno) {
System.out.println(name);
System.out.println(telno);
theDirectory[size] = new DirectoryEntry(name, telno);
size = size + 1;
}
// Searches the array of directory entries for a specific name
private int find(String name) {
int result = -1;
for (int count = 0; count < size; count++) {
if (theDirectory[count].getName().equals(name)) {
result = count;
}
System.out.println(result);
}
return result;
}
// Creates a new array of directory entries with twice the capacity
// of the previous one
private void reallocate() {
capacity = capacity * 2;
DirectoryEntry[] newDirectory = new DirectoryEntry[capacity];
System.arraycopy(theDirectory, 0, newDirectory,
0, theDirectory.length);
theDirectory = newDirectory;
}
}
ArrayPhoneDirectoryTester.java
import java.util.Scanner;
public class ArrayPhoneDirectoryTester {
public static void main(String[] args) {
//create a new ArrayPhoneDirectory
PhoneDirectory newTest = new ArrayPhoneDirectory();
newTest.loadData("telnos.txt");
System.out.println("loadData tested successfully");
System.out.print("Please enter a name to look up: ");
Scanner in = new Scanner(System.in);
String name = in.next();
String entryNo = newTest.lookUpEntry(name);
System.out.println(entryNo);
}
}
telnos.txt
John
123
Bill
23
Hello
23455
Frank
12345
Dkddd
31231

In your code:
Scanner read = new Scanner("telnos.txt");
Is not going to load file 'telnos.txt'. It is instead going to create a Scanner object that scans the String "telnos.txt".
To make the Scanner understand that it has to scan a file you have to either:
Scanner read = new Scanner(new File("telnos.txt"));
or create a File object and pass its path to the Scanner constructor.
In case you are getting "File not found" errors you need to check the current working directory. You could run the following lines and see if you are indeed in the right directory in which the file is:
String workingDir = System.getProperty("user.dir");
System.out.println("Current working directory : " + workingDir);
You need to also catch the FileNotFoundException in the function as follows:
public void loadData(String sourceName) {
try {
Scanner read = new Scanner(new File("telnos.txt")).useDelimiter("\\Z");
int i = 1;
String name = null;
String telno = null;
while (read.hasNextLine()) {
if (i % 2 != 0)
name = read.nextLine();
else {
telno = read.nextLine();
add(name, telno);
}
i++;
}
}catch(FileNotFoundException ex) {
System.out.println("File not found:"+ex.getMessage);
}
}

You are actually parsing the filename not the actual file contents.
Instead of:
new Scanner("telnos.txt")
you need
new Scanner( new File( "telnos.txt" ) )
http://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html

I'm getting a NullPointerException error in Eclipse

I'm getting a NullPointerException error in Eclipse. Code as it stands right now:
Java:
import java.io.File;
import java.io.IOException;
import java.util.Scanner;
import java.util.ArrayList;
import java.util.Collections;
import static java.lang.System. * ;
public class MadLib {
private ArrayList<String> verbs = new ArrayList<String>();
private ArrayList<String> nouns = new ArrayList<String>();
private ArrayList<String> adjectives = new ArrayList<String>();
public MadLib() {}
public MadLib(String fileName) {
//load stuff
try {
Scanner file = new Scanner(new File(fileName));
}
catch(Exception e) {
out.println("Houston we have a problem!");
}
}
public void loadNouns() {
nouns = new ArrayList < String > ();
try {
Scanner chopper = new Scanner("nouns.dat");
while (chopper.hasNext()) {
nouns.add(chopper.next());
}
chopper.close();
out.println(nouns);
}
catch(Exception e) {
out.println("Will");
}
}
public void loadVerbs() {
verbs = new ArrayList < String > ();
try {
Scanner chopper = new Scanner("verbs.dat");
while (chopper.hasNext()) {
verbs.add(chopper.next());
}
chopper.close();
}
catch(Exception e) {
out.println("run");
}
}
public void loadAdjectives() {
adjectives = new ArrayList < String > ();
try {
Scanner chopper = new Scanner("adjectives.dat");
while (chopper.hasNext()) {
adjectives.add(chopper.next());
}
chopper.close();
}
catch(Exception e) {}
}
public String getRandomVerb() {
String verb = "";
int num = 0;
num = (int)(Math.random() * verbs.size());
verb = verbs.get(num);
return verb;
}
public String getRandomNoun() {
String noun = "";
int num = 0;
num = (int)(Math.random() * nouns.size());
noun = nouns.get(num);
return noun;
}
public String getRandomAdjective() {
String adj = "";
int num = 0;
num = (int)(Math.random() * adjectives.size());
adj = adjectives.get(num);
return adj;
}
public String toString() {
String output = "The " + getRandomNoun() + getRandomVerb() + " after the " + getRandomAdjective() + getRandomAdjective() + getRandomNoun() + " while the " + getRandomNoun() + getRandomVerb() + " the " + getRandomNoun();
return output;
}
}
Eclipse is pointing to the issue occurring at the linenum = (int)(Math.random()*nouns.size()); but this seems to not make much sense to me.
I have the private ArrayList<String> initialized at the method loadNouns. I origianlly had ArrayList<String> nouns initialized at getRandomNoun(), but that threw a different error, so I was advised to move the initialization statement to the loadNouns method.
Runner Class:
import static java.lang.System.*;
public class Lab16d
public static void main( String args[] ) {
//make a new MadLib
MadLib fun = new MadLib();
out.println(fun);
}
Update:
The real issue appears to be that ArrayList<String> nouns never is "loaded up" with the separate strings which are supposed to be scanned in from the nouns.dat file
Update 2:
Java:
import java.io.File;
import java.io.IOException;
import java.util.Scanner;
import java.util.ArrayList;
import java.util.Collections;
import static java.lang.System. * ;
public class MadLib {
private ArrayList<String> verbs = new ArrayList<String>();
private ArrayList<String> nouns = new ArrayList<String>();
private ArrayList<String> adjectives = new ArrayList<String>();
public MadLib() {
loadNouns();
loadVerbs();
loadAdjectives();
out.println(nouns);
}
public MadLib(String fileName) {
//load stuff
loadNouns();
loadVerbs();
loadAdjectives();
try {
Scanner file = new Scanner(new File(fileName));
}
catch(Exception e) {
out.println("Houston we have a problem!");
}
}
public void loadNouns() {
nouns = new ArrayList < String > ();
try {
//nouns = new ArrayList<String>();
String nou = "";
Scanner chopper = new Scanner(new File("nouns.dat"));
//chopper.nextLine();
while (chopper.hasNext()) {
nou = chopper.next();
out.println(nou);
nouns.add(nou);
//chopper.nextLine();
}
//chopper.close();
out.println(nouns.size());
}
catch(Exception e) {
out.println("Will");
}
}
public void loadVerbs() {
verbs = new ArrayList < String > ();
try {
Scanner chopper = new Scanner(new File("verbs.dat"));
while (chopper.hasNext()) {
verbs.add(chopper.next());
chopper.nextLine();
}
chopper.close();
}
catch(Exception e) {
out.println("run");
}
}
public void loadAdjectives() {
adjectives = new ArrayList < String > ();
try {
Scanner chopper = new Scanner(new File("adjectives.dat"));
while (chopper.hasNext()) {
adjectives.add(chopper.next());
chopper.nextLine();
}
chopper.close();
}
catch(Exception e) {}
}
public String getRandomVerb() {
String verb = "";
int num = 0;
num = (int)(Math.random() * (verbs.size() - 1));
verb = verbs.get(num);
return verb;
}
public String getRandomNoun() {
String noun = "";
int num = 0;
if (nouns == null) {
loadNouns();
}
double rand = (Math.random());
num = (int)(rand * (nouns.size() - 1));
out.println(num);
noun = nouns.get((int) num);
out.print(noun);
return noun;
}
public String getRandomAdjective() {
String adj = "";
int num = 0;
num = (int)(Math.random() * (adjectives.size() - 1));
adj = adjectives.get(num);
return adj;
}
public String toString() {
String output = "The " + getRandomNoun() + getRandomVerb() + " after the " + getRandomAdjective() + getRandomAdjective() + getRandomNoun() + " while the " + getRandomNoun() + getRandomVerb() + " the " + getRandomNoun();
return output;
}
}

You are creating an instance of MadLib, then printing the object in a println in your Runner class...
//make a new MadLib
MadLib fun = new MadLib();
out.println(fun);
The out.println calls the toString() method you overrode in MadLib...
String output = "The " + getRandomNoun() + getRandomVerb() + " after the " + getRandomAdjective() + getRandomAdjective() + getRandomNoun() + " while the " + getRandomNoun() + getRandomVerb() + " the " + getRandomNoun();
return output;
Your MadLib object has 3 ArrayLists you never initialized, so they are null...
private ArrayList<String> verbs;
private ArrayList<String> nouns;
private ArrayList<String> adjectives
The easiest way to fix the NullPointerException is to initialize the variables....
private ArrayList<String> verbs = new ArrayList<String>();
private ArrayList<String> nouns = new ArrayList<String>();
private ArrayList<String> adjectives = new ArrayList<String>();
However, what I really think you want to do is load all the nouns, verbs and adjectives when your object is constructed so your toString actually prints something useful. I'd add this to your constructor as well...
public MadLib() {
loadNouns();
loadVerbs();
loadAdjectives();
}
Edit: Your getRandom methods need to check if the list is empty to avoid the IndexOutOfBounds exception as well...
public String getRandomVerb() {
String verb = "";
if (!verbs.isEmpty()) {
int num = (int) (Math.random() * verbs.size() - 1);
verb = verbs.get(num);
}
return verb;
}
public String getRandomNoun() {
String noun = "";
if (!nouns.isEmpty()) {
int num = (int) (Math.random() * nouns.size() - 1);
noun = nouns.get(num);
}
return noun;
}
public String getRandomAdjective() {
String adj = "";
if (!adjectives.isEmpty()) {
int num = (int) (Math.random() * adjectives.size());
adj = adjectives.get(num);
}
return adj;
}
Hope that helps