I am an Undergarduate student who is trying to get classes to work with association. All of the classes below compile and Main will run, but then falls over with a NullPointerException (which is commented in main)
I have been trying to find out what is going wrong for two days and getting no where.
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import java.io.*;
import java.util.*;
public class Codex
{
Dictionary myDictionary;
Codex(Dictionary aDictionary)
{
myDictionary = aDictionary;
myDictionary.setCodex(this);
}
//Numbers method, to convert words into numbers
public
String CodexConvert(String
word)
{
StringBuffer nos = new StringBuffer("");
char c; //c is the character in the word
char n; //the character in the output string, ie numbers
//loop through while word untill all letters are converted
for (int i=0; i<word.length(); i++)
{
c = word.charAt(i);
switch (c)
{
case 'a':
case 'b':
case 'c':
n='2';
break;
case 'd':
case 'e':
case 'f':
n='3';
break;
case 'g':
case 'h':
case 'i':
n='4';
break;
case 'j':
case 'k':
case 'l':
n='5';
break;
case 'm':
case 'n':
case 'o':
n='6';
break;
case 'p':
case 'q':
case 'r':
case 's':
n='7';
break;
case 't':
case 'u':
case 'v':
n='8';
break;
case 'w':
case 'x':
case 'y':
case 'z':
n='9';
break;
default:
n='0';
break;
}
nos.append(n);
}
return new String(nos);
}
}
-------------------------------------------------
import java.io.*;
import java.util.*;
public class Dictionary
{
public HashMap map;
private String wordnos, word;
Codex myCodex;
public Dictionary()
{
}
//dictionary method
void Dictionary()
throws FileNotFoundException, IOException
{
//Read in the dictionary
word file BufferedReader readDictionary = new BufferedReader(new FileReader("MyWords"));
//store each word, by line in variable
word = readDictionary.readLine();
while (word != null)
{
wordnos = myCodex.CodexConvert(word); //converts words into numbers + stores them in wordnos
//add wordnos to map, if it does not exist
if (!map.containsKey(wordnos))
{
map.put(wordnos, new Vector()); //create new vector for wordnos
} //add words to words to match wordnos vectors
((Vector)map.get(wordnos)).add(word);
word = readDictionary.readLine();
}
readDictionary.close();
}
void setCodex(Codex aCodex)
{
myCodex = aCodex;
}
}
------------------------------------------------
//Main section to
test the dictionary and Codex
import java.io.*;
import java.util.*;
public class DictTest
{
public static void main(String[] args)
{
String numbersIn; //variable for users input
//recieve and store users input
System.out.println("Enter your numbers here : ");
System.out.println();
//read in number string and store in numbersIn variable
numbersIn= KBInput.readString();
//create object MyDictionary and print out results
Dictionary RatsDictionary = new Dictionary();
Codex RatsCodex = new Codex(RatsDictionary);
System.out.println();
//Error here : Exception in
thread "main" java.lang.NullPointerException
System.out.println("Words that match your number input are:" +RatsDictionary.map.get(numbersIn));
}
}
