Conversion from prefix to infix: Null Pointer exception - java

I am trying to convert an expression from infix to postfix. I've tried debugging the code but I keep getting null pointer exception when the variable is popped. The input for which I get the error is :
(=> (NOT (award)) (badgrade))
The output after I get the error is (NOT award)
Please tell me if need to edit the Q to post lesser code/ add more comments/ provide any more information. Thanks!
public class toInfix1 {
Stack<String> symbol = new Stack<String>();
Stack<String> variable = new Stack<String>();
Stack<String> operator = new Stack<String>();
static String inputfile = "kb2.txt";
ArrayList<String> infix = new ArrayList<String>();
public void toPrefix1() {
try {
File f = new File(inputfile);
FileReader fr = new FileReader(f);
BufferedReader bf = new BufferedReader(fr);
String str;
String kb = "";
while ((str = bf.readLine()) != null) {
Pattern pattern = Pattern.compile("[(]|[)]|<=>|=>|\\w+|^\\s+");
Matcher m = pattern.matcher(str);
//int a = 0;
System.out.println("KB" + kb);
while (m.find()) {
String node1 = m.group();
System.out.println("Node1" + node1);
//If (
if (node1.equals("(")) {
symbol.push(node1);
} else if (node1.equals("OR") || node1.equals("AND")
|| node1.equals("NOT") || node1.equals("=>")
|| node1.equals("<=>")) {
operator.push(node1);
//If )
} else if (node1.equals(")")) {
//Pop symbol (
if(!variable.empty()&& !operator.empty() && !symbol.empty()){
String symbol1 = "", op = "";
if (symbol.peek() != null && !symbol.empty()) {
symbol1 = symbol.pop();
}
//Pop if operator AND OR => <=> (Binary)
if (operator.peek() != null && !operator.empty()) {
op = operator.pop();
if (op.equals("AND") || op.equals("OR")
|| op.equals("=>") || op.equals("<=>")) {
String var2 = "";
String var1 = "";
if (variable.peek() != null && !variable.empty()) {
var1 = variable.pop();
}//Error occurs in the following if condition
if (variable.peek() != null && !variable.empty()) {
var2 = variable.pop();
}
kb = "(" + var1 + op + var2 + ")";
variable.push(kb);
//Pop if operator NOT (Unary)
} else if (op.equals("NOT")) {
String var1 = "";
if (variable.peek() != null && !variable.empty()) {
var1 = variable.pop();
}
kb = "(" + op + var1 + ")";
variable.push(kb);
//No operator after popping )
}
}
}
//If there are no operators
} else {
variable.push(node1);
}
}
}
fr.close();
} catch (Exception e) {
System.err.println("Error thrown" + e.getMessage());
}
}
public static void main(String[] args) {
System.out.println("In new file");
toInfix1 inf1 = new toInfix1();
inf1.toPrefix1();
System.out.println("Completed");
}
}


I was trying to access an element which was null at variable.peek(). removing all peek conditions, will make the program work.

Related

Java, Spring Boot: Question about numberformatexception

this NumberFormatException is driving me insane. I cannot seem to find any reason for the exception.
For context i am running a maven built spring boot application as a jar when the error occurs. It is running without errors inside the ide.
The error message:
java.lang.NumberFormatException: For input string: "9150287"
The piece of code producing the error message:
String substring = st.substring(indexLastAddedString + 1, i).trim();
System.out.println("Substring to be parsed: " + substring);
number = Integer.parseInt(substring);
So far i tried every method of parsing the string to integer.
I also logged the string and tried different strings.
//Edit
Here is the minimal reproducible example:
File file = new File("somefile.txt");
BufferedReader br = new BufferedReader(new FileReader(file));
String st;#
int numberOfSemicolon = 0;
int indexLastAddedString = 0;
String description = "";
int adressNumber = -1;
int number = 0;
while ((st = br.readLine()) != null) {
for(int i = 0; i < st.length(); i++) {
if(st.charAt(i) == ';') {
numberOfSemicolon++;
}
//add the description of project
if(st.charAt(i) == ';' && numberOfSemicolon == 1) {
description = st.substring(indexLastAddedString,i).replace("\""," ");
indexLastAddedString = i;
}
//add the adresNumber of project
if(st.charAt(i) == ';' && numberOfSemicolon == 2) {
String identifier = st.substring(indexLastAddedString+1, i);
adressNumber = customers.get(identifier) == null ? -1 : customers.get(identifier).getId();
indexLastAddedString = i;
}
//add the belegnumber of project
if(st.charAt(i) == ';' && numberOfSemicolon == 3) {
String substring = st.substring(indexLastAddedString + 1, i).trim();
System.out.println("Substring to be parsed: " + substring);
try {
} catch (NumberFormatException er) {
er.printStackTrace();
}
number = Integer.parseInt(substring);
projects.add(new Project(number,description, adressNumber));
indexLastAddedString = i+1;
numberOfSemicolon = 0;
}
}
}
The text file contains data in the following format (as an example):
projectdescription;adressNumber;projectNumber;

Identify whether my string contains any hex code or not in java

I want to identify whether my string contains any hex code or not.
Use cases
String input1 = "hello check this input ";
String input2 = "hello check 0x740x680x690x73 input";
String input3 = "0x680x650x6c0x6c0x6f0x200x630x680x650x630x6b0x200x740x680x690x730x200x690x6e0x700x750x74";
isContainHex(input1) should return false
isContainHex(input2) should return true
isContainHex(input3) should return true
I have tried
String input2 = "hello check 0x740x680x690x73 input";
if(input2.contains("0x") || input2.contains("\\x"))
{
System.out.println("string contains hex");
}
and I am able to find hex but,
If My input contains hex like
String input4 = "h68h65h6ch6ch6f check this input ";
Here I cant check input4.contains("h")
Any one have solution for this?
is there any standard library by which I can achive same?
Update
I have wrote following code, and its working well but taking time.
Now can it be optimize
try
{
if (input != null && input.trim().length() > 0)
{
String originalHex = null;
StringBuilder output = new StringBuilder();
String inputArray[] = null;
if (StringUtils.countMatches(input, "\\x") > 3)
{
originalHex = input.substring(input.indexOf("\\x"), input.lastIndexOf("\\x", input.length()) + 4);
inputArray = input.split("\\Q\\x\\E");
}
else if (StringUtils.countMatches(input, "0x") > 3)
{
originalHex = input.substring(input.indexOf("0x"), input.lastIndexOf("0x", input.length()) + 4);
inputArray = input.split("0x");
}
if (inputArray != null && inputArray.length > 0)
{
for (String str: inputArray)
{
int strLength = str.trim().length();
if (strLength == 2)
{
output.append((char)Integer.parseInt(str, 16));
}
else if (strLength > 2)
{
if (strLength % 2 != 0)
{
strLength = strLength - 1;
}
for (int i = 0; i < strLength; i += 2)
{
String val = str.substring(i, i+2);
if (val.matches("\\d+"))
{
output.append((char)Integer.parseInt(val, 16));
}
}
}
}
input = input.replaceAll("\\Q" + originalHex + "\\E", output.toString());
}
}
}
catch(Exception ex)
{
ex.printStackTrace();
}
syso(input);

How to allow Special Character '&' in java

I have the following code to allow the special character :
public static String replacer1(StringBuffer outBuffer) {
String data = "";
StringBuffer tempBuffer = null;
try {
if (outBuffer != null) {
data = outBuffer.toString();
tempBuffer = new StringBuffer();
int incrementor = 0;
int dataLength = data.length();
while (incrementor < dataLength) {
char charecterAt = data.charAt(incrementor);
if (charecterAt == '%') {
tempBuffer.append("<percentage>");
} else if (charecterAt == '+') {
tempBuffer.append("<plus>");
}else if (charecterAt == '-') {
tempBuffer.append("<hyphen>");
} else if (charecterAt == '&') {
tempBuffer.append("<AMPERSAND>");
} else if (charecterAt == '_') {
tempBuffer.append("<UNDERSCORE>");
}
else {
tempBuffer.append(charecterAt);
}
incrementor++;
}
data = tempBuffer.toString();
data = URLDecoder.decode(data, "utf-8");
data = data.replaceAll("<percentage>", "%");
data = data.replaceAll("<plus>", "+");
data = data.replaceAll("<hyphen>", "-");
data = data.replaceAll("<AMPERSAND>", "&");
data = data.replaceAll("<UNDERSCORE>", "_");
//data = data.replaceAll("\"", "");
data = data.replaceAll("'", "");
data = data.trim();
}
} catch (Exception e) {
e.printStackTrace();
}
return data;
}
all the special charcters are comming except '&'.
IS there any other way?
Please help

HashMap key that is made up of multiple tokens and has non-null value mapping returns null

I am creating a currency exchange application from csv data and have hit a road block. I am storing the main currency exchange rate table in a LinkedHashMap of the following type:
LinkedHashMap[String,LinkedHashMap[String,Double]]
It will store the data as [Country, [Year,Rate]].
When I print to the console to confirm that the Map is being populated properly, I receive confirmation of a full KeySet and proper value mappings. Additionally, the application runs smoothly for any country names consisting of only one token. However, countries with more than one token in their names return null even though the map is populated with that key and its correct corresponding value.
For example, printing getExchangeRates() will return all K-V pairs including the following:
Australia={1960=0.8929, 1961=0.8929, 1962=0.8929, 1963=0.8929, 1964=0.8929, 1965=0.8929...},
Czech Republic={1990=21.145, 1991=27.92, 1992=28.37, 1993=29.153, 1994=28.785, 1995=26.541...},
New Zealand={1960=0.7143, 1961=0.7155, 1962=0.7192, 1963=0.7192, 1964=0.7192, 1965=0.7192...}
Printing getExchangeRates().get("Australia") will return the LinkedHashMap of years and rates; however, printing getExchangeRates().get("Czech Republic") or getExchangeRates().get("New Zealand") will return null.
Does anyone know why this would be happening? I am befuddled.
Code and csv snippet included for reference, but as I said, the HashMap appears to be populating correctly.
,1960,1961,1962,1963,1964,1965,1966,1967,1968,1969,1970,1971,1972,1973,1974,1975,1976,1977,1978,1979,1980,1981,1982,1983,1984,1985,1986,1987,1988,1989,1990,1991,1992,1993,1994,1995,1996,1997,1998,1999,2000,2001,2002,2003,2004,2005,2006,2007,2008
Australia,0.8929,0.8929,0.8929,0.8929,0.8929,0.8929,0.8929,0.8929,0.8929,0.8929,0.8929,0.8827,0.8387,0.7041,0.6967,0.7639,0.8183,0.9018,0.8737,0.8946,0.8782,0.8702,0.9859,1.11,1.1395,1.4319,1.496,1.4282,1.2799,1.2646,1.2811,1.2838,1.3617,1.4706,1.3678,1.349,1.2779,1.3474,1.5918,1.55,1.7248,1.9334,1.8406,1.5419,1.3598,1.3095,1.328,1.1951,1.1922
Austria,1.88949,1.88949,1.88949,1.88949,1.88949,1.88949,1.88949,1.88949,1.88949,1.88949,1.88949,1.81394,1.67985,1.42293,1.35844,1.26573,1.30373,1.20106,1.05533,0.97145,0.94024,1.15745,1.23975,1.30544,1.45412,1.50356,1.1095,0.91877,0.89734,0.96151,0.82628,0.84852,0.79862,0.84534,0.83005,0.73265,0.76936,0.88691,0.89962,0.93863,1.0854,1.11751,1.06255,0.88603,0.80537,0.80412,0.79714,0.73064,0.68268
Belgium,1.23947,1.23947,1.23947,1.23947,1.23947,1.23947,1.23947,1.23947,1.23947,1.23947,1.23947,1.21145,1.09109,0.9662,0.96558,0.91173,0.957,0.88852,0.78067,0.72679,0.72488,0.92041,1.13264,1.26752,1.43243,1.47194,1.10739,0.92549,0.91146,0.9768,0.82841,0.84651,0.79697,0.85762,0.82936,0.73079,0.76752,0.88681,0.89982,0.93863,1.0854,1.11751,1.06255,0.88603,0.80537,0.80412,0.79714,0.73064,0.68268
Canada,0.9698,1.0131,1.0701,1.0811,1.0811,1.0811,1.0811,1.0811,1.0811,1.0811,1.0477,1.0098,0.9899,1.0001,0.978,1.0172,0.986,1.0635,1.1407,1.1714,1.1692,1.1989,1.2337,1.2324,1.2951,1.3655,1.3895,1.326,1.2307,1.184,1.1668,1.1457,1.2087,1.2901,1.3656,1.3724,1.3635,1.3846,1.4835,1.4857,1.4851,1.5488,1.5693,1.4011,1.301,1.2118,1.1344,1.0741,1.067
Czech Republic,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,21.145,27.92,28.37,29.153,28.785,26.541,27.145,31.698,32.281,34.569,38.598,38.035,32.739,28.209,25.7,23.957,22.596,20.294,17.072
Denmark,6.9071,6.9071,6.9071,6.9071,6.9071,6.9071,6.9071,6.9565,7.5,7.5,7.5,7.4169,6.9493,6.0495,6.0949,5.7462,6.045,6.0032,5.5146,5.261,5.6359,7.1234,8.3324,9.145,10.3566,10.5964,8.091,6.8403,6.7315,7.3102,6.1886,6.3965,6.0361,6.4839,6.3606,5.6024,5.7987,6.6045,6.7008,6.9762,8.0831,8.3228,7.8947,6.5877,5.9911,5.9969,5.9468,5.4437,5.0981
Finland,0.5382,0.5382,0.5382,0.5382,0.5382,0.5382,0.5382,0.58025,0.70638,0.70638,0.70638,0.70375,0.69736,0.64267,0.6347,0.61871,0.64995,0.6777,0.69249,0.65515,0.62735,0.72577,0.81074,0.93682,1.01081,1.04241,0.85263,0.73928,0.7035,0.72173,0.64307,0.68015,0.75339,0.96074,0.87853,0.73442,0.77258,0.87314,0.89881,0.93863,1.0854,1.11751,1.06255,0.88603,0.80537,0.80412,0.79714,0.73064,0.68268
France,0.75266,0.75266,0.75266,0.75266,0.75266,0.75266,0.75266,0.75266,0.75266,0.79185,0.84673,0.84496,0.769,0.67959,0.7339,0.65343,0.72855,0.74907,0.68802,0.64858,0.64419,0.8285,1.00191,1.16186,1.33227,1.36978,1.05588,0.91633,0.90812,0.97264,0.83013,0.86014,0.80704,0.86335,0.8464,0.76095,0.77986,0.8898,0.89938,0.93863,1.0854,1.11751,1.06255,0.88603,0.80537,0.80412,0.79714,0.73064,0.68268
Germany,2.14743,2.06221,2.04517,2.04517,2.04517,2.04517,2.04517,2.04517,2.04517,2.01619,1.87133,1.78481,1.63033,1.36648,1.3231,1.25793,1.28743,1.18731,1.027,0.93714,0.92936,1.15552,1.2407,1.30546,1.45511,1.50523,1.11026,0.91899,0.89795,0.96125,0.82611,0.84851,0.79846,0.84533,0.82972,0.73275,0.76938,0.88661,0.8997,0.93863,1.0854,1.11751,1.06255,0.88603,0.80537,0.80412,0.79714,0.73064,0.68268
Greece,0.08804,0.08804,0.08804,0.08804,0.08804,0.08804,0.08804,0.08804,0.08804,0.08804,0.08804,0.08804,0.08804,0.08694,0.08804,0.09406,0.10717,0.10811,0.10784,0.1087,0.12507,0.16261,0.19605,0.25844,0.33079,0.40534,0.4108,0.39745,0.41632,0.47665,0.46519,0.5349,0.55942,0.67278,0.71197,0.67986,0.70642,0.80134,0.86729,0.89698,1.07234,1.11751,1.06255,0.88603,0.80537,0.80412,0.79714,0.73064,0.68268
Hungary,..,..,..,..,..,..,..,..,60,60,60,59.82,55.26,48.97,46.75,43.97,41.58,40.96,37.91,35.58,32.53,34.31,36.63,42.67,48.04,50.12,45.83,46.97,50.41,59.07,63.21,74.74,78.99,91.93,105.16,125.68,152.65,186.79,214.4,237.15,282.18,286.49,257.89,224.31,202.75,199.58,210.39,183.63,172.11
Iceland,0.344,0.401,0.43,0.43,0.43,0.43,0.43,0.442,0.622,0.88,0.88,0.88,0.883,0.901,1,1.537,1.822,1.989,2.711,3.526,4.798,7.224,12.352,24.843,31.694,41.508,41.104,38.677,43.014,57.042,58.284,58.996,57.546,67.603,69.944,64.692,66.5,70.904,70.958,72.335,78.616,97.425,91.662,76.709,70.192,62.982,70.18,64.055,87.948
Ireland,0.45347,0.45347,0.45347,0.45347,0.45347,0.45347,0.45347,0.45977,0.52906,0.52906,0.52906,0.52176,0.50839,0.51827,0.54313,0.57397,0.70662,0.7279,0.66217,0.62038,0.61792,0.78889,0.89461,1.02173,1.1714,1.20068,0.94358,0.85443,0.83354,0.89585,0.76767,0.78888,0.74625,0.85993,0.84898,0.79198,0.79362,0.83757,0.8917,0.93863,1.0854,1.11751,1.06255,0.88603,0.80537,0.80412,0.79714,0.73064,0.68268
Italy,0.32226,0.32279,0.32279,0.32279,0.32279,0.32279,0.32279,0.32279,0.32279,0.32279,0.32279,0.32017,0.30121,0.30109,0.33587,0.33717,0.42987,0.45572,0.4383,0.4291,0.44232,0.58709,0.69851,0.78442,0.90739,0.98614,0.76994,0.66936,0.67223,0.70863,0.61877,0.64072,0.63649,0.81273,0.83276,0.84127,0.79687,0.87958,0.89668,0.93863,1.0854,1.11751,1.06255,0.88603,0.80537,0.80412,0.79714,0.73064,0.68268
Japan,360,360,360,360,360,360,360,360,360,360,360,349.33,303.17,271.7,292.08,296.79,296.55,268.51,210.44,219.14,226.74,220.54,249.08,237.51,237.52,238.54,168.52,144.64,128.15,137.96,144.79,134.71,126.65,111.2,102.21,94.06,108.78,120.99,130.91,113.91,107.77,121.53,125.39,115.93,108.19,110.22,116.3,117.75,103.36
Korea,..,..,..,..,..,..,271.3,270.5,276.7,288.2,310.6,347.2,392.9,398.3,404.5,484,484,484,484,484,607.4,681,731.1,775.8,806,870,881.5,822.6,731.5,671.5,707.8,733.4,780.7,802.7,803.4,771.3,804.5,951.3,1401.4,1188.8,1131,1291,1251.1,1191.6,1145.3,1024.1,954.8,929.3,1102.1
Luxembourg,1.23947,1.23947,1.23947,1.23947,1.23947,1.23947,1.23947,1.23947,1.23947,1.23947,1.23947,1.21145,1.09109,0.9662,0.96558,0.91173,0.957,0.88852,0.78067,0.72679,0.72488,0.92041,1.13264,1.26752,1.43243,1.47194,1.10739,0.92549,0.91146,0.9768,0.82841,0.84651,0.79697,0.85762,0.82936,0.73079,0.76752,0.88681,0.89982,0.93863,1.0854,1.11751,1.06255,0.88603,0.80537,0.80412,0.79714,0.73064,0.68268
Mexico,0.013,0.013,0.013,0.013,0.013,0.013,0.013,0.013,0.013,0.013,0.013,0.013,0.013,0.013,0.013,0.013,0.015,0.023,0.023,0.023,0.023,0.025,0.056,0.12,0.168,0.257,0.612,1.378,2.273,2.462,2.813,3.018,3.095,3.116,3.375,6.419,7.599,7.918,9.136,9.56,9.456,9.342,9.656,10.789,11.286,10.898,10.899,10.928,11.13
Netherlands,1.72436,1.6563,1.64268,1.64268,1.64268,1.64268,1.64268,1.64268,1.64268,1.64268,1.64268,1.58933,1.45641,1.26857,1.21993,1.14761,1.19977,1.11369,0.98179,0.91028,0.90217,1.13227,1.21169,1.29515,1.45604,1.50719,1.11177,0.91922,0.89693,0.96235,0.82631,0.84842,0.79796,0.84281,0.82588,0.72863,0.76503,0.88545,0.90018,0.93863,1.0854,1.11751,1.06255,0.88603,0.80537,0.80412,0.79714,0.73064,0.68268
New Zealand,0.7143,0.7155,0.7192,0.7192,0.7192,0.7192,0.7192,0.7337,0.8929,0.8929,0.8929,0.8806,0.8368,0.7368,0.7154,0.8323,1.0049,1.0303,0.9644,0.9785,1.0267,1.1528,1.3326,1.4968,1.764,2.0234,1.9132,1.6946,1.5264,1.6722,1.6762,1.7335,1.8618,1.8505,1.6865,1.5239,1.4549,1.5124,1.8683,1.8896,2.2012,2.3788,2.1622,1.7221,1.5087,1.4203,1.5421,1.3607,1.4227
Norway,7.1429,7.1429,7.1429,7.1429,7.1429,7.1429,7.1429,7.1429,7.1429,7.1429,7.1429,7.0418,6.5883,5.7658,5.5397,5.2269,5.4565,5.3235,5.2423,5.0641,4.9392,5.7395,6.454,7.2964,8.1615,8.5972,7.3947,6.7375,6.517,6.9045,6.2597,6.4829,6.2145,7.0941,7.0576,6.3352,6.4498,7.0734,7.5451,7.7992,8.8018,8.9917,7.9838,7.0802,6.7408,6.4425,6.4133,5.8617,5.64
Poland,..,..,..,..,..,..,0.0004,0.0004,0.0004,0.0004,0.0004,0.0004,0.0004,0.0003,0.0003,0.0003,0.0003,0.0003,..,0.004,0.0044,0.0051,0.0085,0.0092,0.0113,0.0147,0.0175,0.0265,0.0431,0.1439,0.95,1.0576,1.3626,1.8115,2.2723,2.425,2.6961,3.2793,3.4754,3.9671,4.3461,4.0939,4.08,3.8891,3.6576,3.2355,3.1032,2.768,2.4092
Portugal,0.1434,0.1434,0.1434,0.1434,0.1434,0.1434,0.1434,0.1434,0.1434,0.1434,0.1434,0.14122,0.13494,0.12228,0.12673,0.12746,0.15078,0.19092,0.21916,0.24403,0.24971,0.30699,0.39641,0.55257,0.73019,0.84993,0.74614,0.70272,0.71804,0.7854,0.71106,0.72067,0.67337,0.80207,0.82797,0.75371,0.76937,0.87445,0.89835,0.93863,1.0854,1.11751,1.06255,0.88603,0.80537,0.80412,0.79714,0.73064,0.68268
Slovak Republic,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,1.0214,1.0637,0.9863,1.0175,1.1159,1.1695,1.373,1.5281,1.6051,1.5046,1.2206,1.0707,1.0296,0.9858,0.8197,0.7091
Spain,0.36061,0.36061,0.36061,0.36061,0.36061,0.36061,0.36061,0.37063,0.42071,0.42071,0.42071,0.41752,0.38628,0.35015,0.3467,0.34502,0.4021,0.45654,0.46078,0.40343,0.43094,0.55487,0.66027,0.86203,0.96619,1.02199,0.84171,0.74212,0.7001,0.71147,0.61264,0.62452,0.61531,0.76485,0.8051,0.7494,0.76125,0.87997,0.89788,0.93863,1.0854,1.11751,1.06255,0.88603,0.80537,0.80412,0.79714,0.73064,0.68268
Sweden,5.1732,5.1732,5.1732,5.1732,5.1732,5.1732,5.1732,5.1732,5.1732,5.1732,5.1732,5.1168,4.7624,4.3673,4.4394,4.1522,4.3559,4.4816,4.5185,4.2871,4.2296,5.0634,6.2826,7.6671,8.2718,8.6039,7.1236,6.3404,6.1272,6.4469,5.9188,6.0475,5.8238,7.7834,7.716,7.1333,6.706,7.6349,7.9499,8.2624,9.1622,10.3291,9.7371,8.0863,7.3489,7.4731,7.3783,6.7588,6.5911
Switzerland,4.373,4.373,4.373,4.373,4.373,4.373,4.373,4.373,4.373,4.373,4.373,4.1342,3.8193,3.1648,2.9793,2.5813,2.4996,2.4035,1.788,1.6627,1.6757,1.9642,2.0303,2.0991,2.3497,2.4571,1.7989,1.4912,1.4633,1.6359,1.3892,1.434,1.4062,1.4776,1.3677,1.1825,1.236,1.4513,1.4498,1.5022,1.6888,1.6876,1.5586,1.3467,1.2435,1.2452,1.2538,1.2004,1.0831
Turkey,-,-,-,-,-,-,-,-,-,-,-,-,-,-,-,-,-,-,-,-,0.0001,0.0001,0.0002,0.0002,0.0004,0.0005,0.0007,0.0009,0.0014,0.0021,0.0026,0.0042,0.0069,0.011,0.0296,0.0458,0.0814,0.1519,0.2607,0.4188,0.6252,1.2256,1.5072,1.5009,1.4255,1.3436,1.4285,1.3029,1.3015
United Kingdom,0.35714,0.35714,0.35714,0.35714,0.35714,0.35714,0.35714,0.3621,0.41667,0.41667,0.41667,0.41092,0.40039,0.40817,0.42776,0.45204,0.55651,0.57327,0.52151,0.47218,0.4303,0.49764,0.57245,0.65973,0.75181,0.77925,0.6822,0.61193,0.56217,0.61117,0.56318,0.56702,0.56977,0.66676,0.65343,0.63367,0.64096,0.61084,0.60382,0.61806,0.66093,0.69466,0.66722,0.61247,0.54618,0.55,0.54349,0.49977,0.54397
United States,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
Euro area,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,0.76452,0.78756,0.8818,0.89199,0.93863,1.0854,1.11751,1.06255,0.88603,0.80537,0.80412,0.79714,0.73064,0.68268
Brazil,0.0001,0.0001,0.0001,0.0002,0.0005,0.0007,0.0009,0.001,0.0013,0.0016,0.0018,0.002,0.0023,0.0024,0.0026,0.0031,0.0041,0.0055,0.007,0.0104,0.0203,0.0359,0.0693,0.2227,0.7131,2.3925,5.2694,15.137,79.6677,-,-,0.0001,0.0016,0.0322,0.6393,0.9177,1.0051,1.078,1.1605,1.8139,1.8294,2.3496,2.9204,3.0775,2.9251,2.4344,2.1753,1.9471,1.8338
Chile,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,396.77,412.27,419.3,460.29,508.78,539.59,634.94,688.94,691.4,609.53,559.77,530.28,522.46,522.46
China,2.462,2.462,2.462,2.462,2.462,2.462,2.462,2.462,2.462,2.462,2.462,2.462,2.245,1.989,1.961,1.86,1.941,1.858,1.684,1.555,1.498,1.705,1.893,1.976,2.32,2.937,3.453,3.722,3.722,3.765,4.783,5.323,5.515,5.762,8.619,8.351,8.314,8.29,8.279,8.278,8.279,8.277,8.277,8.277,8.277,8.194,7.973,7.608,6.949
Estonia,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,13.223,12.991,11.465,12.038,13.882,14.075,14.678,16.969,17.478,16.612,13.856,12.596,12.584,12.466,11.434,10.694
India,4.77,4.78,4.77,4.78,4.79,4.79,6.3,7.56,7.58,7.59,7.57,7.52,7.59,7.74,8.1,8.38,8.96,8.74,8.19,8.13,7.86,8.66,9.46,10.1,11.36,12.37,12.61,12.96,13.92,16.23,17.5,22.74,25.92,30.49,31.37,32.43,35.43,36.31,41.26,43.06,44.94,47.19,48.61,46.58,45.32,44.1,45.31,41.35,43.51
Indonesia,..,..,..,..,..,..,..,150,296,326,363,392,415,415,415,415,415,415,442,623,627,632,661,909,1026,1111,1283,1644,1686,1770,1843,1950,2030,2087,2161,2249,2342,2909,10014,7855,8422,10261,9311,8577,8939,9705,9159,9141,9699
Israel 1,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,3.0113,3.1917,3.4494,3.8001,4.1397,4.0773,4.2057,4.7378,4.5541,4.482,4.4877,4.4558,4.1081,3.588
Russian Federation,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,0.992,2.191,4.559,5.121,5.785,9.705,24.62,28.129,29.169,31.349,30.692,28.814,28.284,27.191,25.581,24.853
Slovenia,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,..,0.11505,0.3392,0.47255,0.53751,0.49457,0.56486,0.66637,0.69326,0.75851,0.92913,1.01297,1.00254,0.86427,0.80279,0.80414,0.79715,0.73064,0.68268
South Africa,0.713,0.715,0.713,0.715,0.717,0.716,0.717,0.717,0.717,0.718,0.716,0.712,0.773,0.694,0.679,0.74,0.87,0.87,0.87,0.842,0.779,0.878,1.086,1.114,1.475,2.229,2.285,2.036,2.273,2.623,2.587,2.761,2.852,3.268,3.551,3.627,4.299,4.608,5.528,6.109,6.94,8.609,10.541,7.565,6.46,6.359,6.772,7.045,8.261
public static ArrayList<String> getYears() throws IOException {
File file = new File("exchangerates.csv");
BufferedReader br = new BufferedReader(new FileReader(file));
ArrayList<String> years = new ArrayList<String>();
String line = br.readLine();
String year = "";
for(int i = 1; i < line.length(); i++) {
if(line.charAt(i) != ',' && i != line.length()-1) {
year = year + line.charAt(i);
}
else if(i == line.length()-1) {
year = year + line.charAt(i);
years.add(year);
}
else {
years.add(year);
year = "";
}
}
br.close();
return years;
}
public static LinkedHashMap<String,LinkedHashMap<String,Double>> getExchangeRates() throws IOException {
File file = new File("exchangerates.csv");
BufferedReader br = new BufferedReader(new FileReader(file));
//burn first line
br.readLine();
LinkedHashMap<String,LinkedHashMap<String,Double>> exchangeRatesTable = new LinkedHashMap<String,LinkedHashMap<String,Double>>();
String line = null;
while((line = br.readLine()) != null) {
String country = "";
int index = 0;
while(line.charAt(index) != ',') {
country = country + line.charAt(index);
index++;
}
index++; //skip comma
LinkedHashMap<String,Double> yearlyRateMap = new LinkedHashMap<String,Double>();
for(String year : getYears()) {
String rateString = "";
for(int k = index; k < line.length(); k++) {
if(line.charAt(k) != ',' && k != line.length()-1) {
rateString = rateString + line.charAt(k);
index++;
}
else if(k == line.length()-1) {
rateString = rateString + line.charAt(k);
index++;
if(!rateString.equals("..")) {
Double exchangeRate = new Double(rateString);
yearlyRateMap.put(year, exchangeRate);
}
else {
index++;
break;
}
break;
}
else {
if(!rateString.equals("..") && !rateString.equals("-")) {
index++;
Double exchangeRate = new Double(rateString);
yearlyRateMap.put(year, exchangeRate);
}
else {
index++;
break;
}
break;
}
}
}
exchangeRatesTable.put(country, yearlyRateMap);
}
br.close();
return exchangeRatesTable;
}

Null pointer exception when comparing two Strings

I keep getting a Null Pointer Esception when comparing two Strings. I know both of the Strings aren't null so I am not sure what is going on.
public void search() {
while (!openList.isEmpty()) {
currState = openList.removeFirst();
if (currState.equals(goal)) { //this line produces NullPointerException
solution = true;
printSolution(currState);
break;
Goal is a String that I read in from a file.
Openlist is a linked list.
the string start is: 120345678
and goal is: 012345678
public class BFS {
public String start;
public String goal;
public String startFinal;
LinkedList<String> openList;
Map<String, Integer> levelDepth;
Map<String, String> stateHistory;
int nodes = 0;
int limit = 100;
int unique = -1;
int newValue;
int a;
public String currState;
boolean solution = false;
public BFS() {
openList = new LinkedList<String>();
levelDepth = new HashMap<String, Integer>();
stateHistory = new HashMap<String, String>();
this.start = start;
this.goal = goal;
addToOpenList(start, null);// add root
}
public void loadStartState(String filename) throws IOException {
BufferedReader reader = new BufferedReader(new FileReader(filename));
try {
StringBuilder sb = new StringBuilder();
String line = reader.readLine();
StringBuilder currentLine = new StringBuilder();
while (line != null) {
currentLine.delete(0, currentLine.capacity());
currentLine.append(line);
currentLine.deleteCharAt(1);
currentLine.deleteCharAt(2);
sb.append(currentLine.toString());
sb.append("\n");
line = reader.readLine();
}
start = sb.toString();
System.out.println(start);
} finally {
reader.close();
}
}
public void loadGoalState(String filename)throws IOException{
BufferedReader reader = new BufferedReader(new FileReader(filename));
try {
StringBuilder sb = new StringBuilder();
String line = reader.readLine();
StringBuilder currentLine = new StringBuilder();
while (line != null) {
currentLine.delete(0, currentLine.capacity());
currentLine.append(line);
currentLine.deleteCharAt(1);
currentLine.deleteCharAt(2);
sb.append(currentLine.toString());
sb.append("\n");
line = reader.readLine();
}
goal = sb.toString();
System.out.println(goal);
} finally {
reader.close();
}
}
public void search() {
while (!openList.isEmpty()) {
currState = openList.removeFirst();
if (currState != null && currState.equals(goal)) {
solution = true;
printSolution(currState);
break;
} else {
a = currState.indexOf("0");
// left
while (a != 0 && a != 3 && a != 6) {
String nextState = currState.substring(0, a - 1) + "0"
+ currState.charAt(a - 1)
+ currState.substring(a + 1);
addToOpenList(nextState, currState);
nodes++;
break;
}
// up
while (a != 0 && a != 1 && a != 2) {
String nextState = currState.substring(0, a - 3) + "0"
+ currState.substring(a - 2, a)
+ currState.charAt(a - 3)
+ currState.substring(a + 1);
addToOpenList(nextState, currState);
nodes++;
break;
}
// right
while (a != 2 && a != 5 && a != 8) {
String nextState = currState.substring(0, a)
+ currState.charAt(a + 1) + "0"
+ currState.substring(a + 2)
+ currState.substring(a + 1);
addToOpenList(nextState, currState);
nodes++;
break;
}
// down
while (a != 6 && a != 7 && a != 8) {
String nextState = currState.substring(0, a)
+ currState.substring(a + 3, a + 4)
+ currState.substring(a + 1, a + 3) + "0"
+ currState.substring(a + 4);
addToOpenList(nextState, currState);
nodes++;
break;
}
}
}
}
private void addToOpenList(String newState, String oldState) {
if (!levelDepth.containsKey(newState)) {
newValue = oldState == null ? 0 : levelDepth.get(oldState) + 1;
unique++;
levelDepth.put(newState, newValue);
openList.add(newState);
stateHistory.put(newState, oldState);
}
}

Solution
Try this, remove invocation of addToOpenList(start, null) before loading value of goal and start.
Old stuff
Here is null
addToOpenList(start, null);
String currState = openList.removeFirst();
currState == null
Additional information
public BFS() {
this.start = start; //  Variable 'start' is assigned to itself
this.goal = goal; //  Variable 'goal' is assigned to itself
addToOpenList(start, null); // start is null
}
Even my IntelliJ see this :)
Method invocation currState.indexOf("0") at line 115 may produce
java.lang.NullPointerException
115: a = currState.indexOf("0");

Perhaps you could try something like:
public void search(){
currState = openList.removeFirst();
while(currState != null){
if(currState.equals(goal)){
solution = true;
printSolution(currState);
break;
}
currState = openList.removeFirst();
}
}

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