Develop Reference

How toUnit Test ZipOutputStream Or verify the CSVWriter in Java

public void writeEnvToCsv(int customerId, ZipOutputStream zos, List<SummaryDetailsResponse> summaryDetailsResponseList, QueryHelper queryHelper) {
//Headers size = size(No of distinct entities) * 2 + 1
final CsvWriter writer = new CsvWriter(new OutputStreamWriter(zos), new CsvWriterSettings());
final String[] headers = new String[summaryDetailsResponseList.get(0).getEntities().size() * 2 + 1];
String header;
int index = 0, i, k;
headers[index++] = Entities;
for (i = 0; i < summaryDetailsResponseList.get(0).getEntities().size(); i++) {
header = summaryDetailsResponseList.get(0).getEntities().get(i).getEntityType();
if (valueMap.get(header) != null) {
header = valueMap.get(header);
}
headers[index++] = header + " " + Count;
headers[index++] = header + "(s)";
}
writer.writeHeaders(headers);
for (index = 0; index < summaryDetailsResponseList.size(); index++) {
final String[] values = new String[summaryDetailsResponseList.get(index).getEntities().size() * 2 + 1];
i = 0;
k = 0;
values[i++] = summaryDetailsResponseList.get(index).getRecordName();
for (; i <= summaryDetailsResponseList.get(index).getEntities().size() * 2; ) {
values[i++] = String.valueOf(summaryDetailsResponseList.get(index).getEntities().get(k).getEntityData().get(0).getTotal());
try {
StringBuilder strConcat = new StringBuilder();
List<String> hostNames = queryHelper.getHostNames(customerId,
String.valueOf(summaryDetailsResponseList.get(index).getEntities().get(k).getEntityData().get(0).getQuery()));
for (String host : hostNames) {
if (strConcat.toString().equals(""))
strConcat.append(host);
else
strConcat.append(", ").append(host);
}
values[i++] = strConcat.toString();
} catch (Exception e) {
e.printStackTrace();
}
k++;
}
writer.writeRow(CSVUtils.escapeCSVRow(values));
}
writer.flush();
}
Basically I want to write UT to verify this function. Can we verify the CSVWriter that it has written correct data for headers and rows or ZipOutputStream in any way.
I was able to verify the records writer has written if I pass writer to the function instead of creating it inside the function but I don't want to do this.

Only outputting last line of loop

import java.io.*;
import java.util.Random;
public class LargeDataset {
public static void main(String[] args) throws Exception {
File file = new File("src/Salary.txt");
if (file.exists()) {
System.out.print("Sorry this file already exists.");
System.exit(0);
}
String firstName = "";
String lastName = "";
String rank = "";
double salaryRange = 0.0;
for (int i = 1; i <= 1000; i++) {
try (PrintWriter output = new PrintWriter(file))
{
firstName = "FirstName" + i;
lastName = "LastName" + i;
rank = generateRandomRank();
if (rank == "assistant")
salaryRange = generateSalary(50000.00, 80000.00);
else if (rank == "associate")
salaryRange = generateSalary(60000.00, 110000.00);
else
salaryRange = generateSalary(75000.00, 130000.00);
output.printf("%s %s %s $%.2f", firstName, lastName, rank, salaryRange);
output.println();
}
}
}
public static String generateRandomRank() {
String[] rank = {"assistant", "associate", "full"};
Random random1 = new Random();
return rank[random1.nextInt(3)];
}
public static double generateSalary(double minSalary, double maxSalary) {
double randomSalary = minSalary + Math.random() * (maxSalary - minSalary);
return randomSalary;
}
}
Hi everyone. I have a program that generates 1000 lines of text and saves it into a file named Salary. The format of each line is: firstNamei, lastNamei, a random rank, and a random salary that is suited to the rank. However when I run this program it only outputs the 1000th line of the loop. I noticed however, when I don't put the PrintWriter in the try statement and close it after the loop by myself, it runs fine and generates all 1000 lines. Why is it only generating the last line based on how it is right now though?

You should open your PrintWriter once, and then write to it many times from your loop, not the other way around:
try (PrintWriter output = new PrintWriter(file)) {
for (int i = 1; i <= 1000; i++) {
firstName = "FirstName" + i;
lastName = "LastName" + i;
rank = generateRandomRank();
if (rank == "assistant")
salaryRange = generateSalary(50000.00, 80000.00);
else if (rank == "associate")
salaryRange = generateSalary(60000.00, 110000.00);
else
salaryRange = generateSalary(75000.00, 130000.00);
output.printf("%s %s %s $%.2f", firstName, lastName, rank, salaryRange);
output.println();
}
}
You should use the above pattern instead of what you have. If you want an exact fix to your current code, then you may try opening the PrintWriter in append mode:
for (int i=1; i <= 1000; i++) {
try (PrintWriter output = new PrintWriter(new FileOutputStream(file, true)) {
// same logic
}
}
This should also work, because now, even though you create a new PrintWriter for each iteration of the loop (inefficient), you open the underlying file in append mode, so each new line should get written properly.

Every time that you are iterating through your 1000 you are creating a new file
for (int i = 1; i <= 1000; i++) {
try (PrintWriter output = new PrintWriter(file))
...
}
move it before the loop
try (PrintWriter output = new PrintWriter(file)) {
for (int i = 1; i <= 1000; i++) {
}
}

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;
}

The program throws NullPointerException [closed]

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Improve this question
Not sure why it gives me the NullPointerException. Please help.
I am pretty sure all the arrays are full, and i restricted all the loops not to go passed empty spaces.
import java.util.;
import java.io.;
public class TextAnalysis {
public static void main (String [] args) throws IOException {
String fileName = args[0];
File file = new File(fileName);
Scanner fileScanner = new Scanner(file);
int MAX_WORDS = 10000;
String[] words = new String[MAX_WORDS];
int unique = 0;
System.out.println("TEXT FILE STATISTICS");
System.out.println("--------------------");
System.out.println("Length of the longest word: " + longestWord(fileScanner));
read(words, fileName);
System.out.println("Number of words in file wordlist: " + wordList(words));
System.out.println("Number of words in file: " + countWords(fileName) + "\n");
System.out.println("Word-frequency statistics");
lengthFrequency(words);
System.out.println();
System.out.println("Wordlist dump:");
wordFrequency(words,fileName);
}
public static void wordFrequency(String[] words, String fileName) throws IOException{
File file = new File(fileName);
Scanner s = new Scanner(file);
int [] array = new int [words.length];
while(s.hasNext()) {
String w = s.next();
if(w!=null){
for(int i = 0; i < words.length; i++){
if(w.equals(words[i])){
array[i]++;
}
}
for(int i = 0; i < words.length; i++){
System.out.println(words[i] + ":" + array[i]);
}
}
}
}
public static void lengthFrequency (String [] words) {
int [] lengthTimes = new int[10];
for(int i = 0; i < words.length; i++) {
String w = words[i];
if(w!=null){
if(w.length() >= 10) {
lengthTimes[9]++;
} else {
lengthTimes[w.length()-1]++;
}
}
}
for(int j = 0; j < 10; j++) {
System.out.println("Word-length " + (j+1) + ": " + lengthTimes[j]);
}
}
public static String longestWord (Scanner s) {
String longest = "";
while (s.hasNext()) {
String word = s.next();
if (word.length() > longest.length()) {
longest = word;
}
}
return (longest.length() + " " + "(\"" + longest + "\")");
}
public static int countWords (String fileName) throws IOException {
File file = new File(fileName);
Scanner fileScanner = new Scanner(file);
int count = 0;
while(fileScanner.hasNext()) {
String word = fileScanner.next();
count++;
}
return count;
}
public static void read(String[] words, String fileName) throws IOException{
File file = new File(fileName);
Scanner s = new Scanner(file);
while (s.hasNext()) {
String word = s.next();
int i;
for ( i=0; i < words.length && words[i] != null; i++ ) {
words[i]=words[i].toLowerCase();
if (words[i].equals(word)) {
break;
}
}
words[i] = word;
}
}
public static int wordList(String[] words) {
int count = 0;
while (words[count] != null) {
count++;
}
return count;
}
}

There are two problems with this code
1.You didn't do null check,although the array contains null values
2.Your array index from 0-8,if you wan't to get element at 9th index it will throw ArrayIndexOutOfBound Exception.
Your code should be like that
public static void lengthFrequency (String [] words) {
int [] lengthTimes = new int [9];
for(int i = 0; i < words.length; i++) {
String w = words[i];
if(null!=w) //This one added for null check
{
/* if(w.length() >= 10) {
lengthTimes[9]++;
} else {
lengthTimes[w.length()-1]++;
}
}*/
//Don't need to check like that ...u can do like below
for(int i = 0; i < words.length; i++) {
String w = words[i];
if(null!=w)
{
lengthTimes[i] =w.length();
}
}
}
//here we should traverse upto length of the array.
for(int i = 0; i < lengthTimes.length; i++) {
System.out.println("Word-length " + (i+1) + ": " + lengthTimes[i]);
}
}

Your String Array String[] words = new String[MAX_WORDS]; is not initialized,you are just declaring it.All its content is null,calling length method in line 31 will give you null pointer exception.
`

Simple mistake. When you declare an array, it is from size 0 to n-1. This array only has indexes from 0 to 8.
int [] lengthTimes = new int [9];
//some code here
lengthTimes[9]++; // <- this is an error (this is line 29)
for(int i = 0; i < 10; i++) {
System.out.println("Word-length " + (i+1) + ": " + lengthTimes[i]); // <- same error when i is 9. This is line 37

When you declare:
String[] words = new String[MAX_WORDS];
You're creating an array with MAX_WORDS of nulls, if your input file don't fill them all, you'll get a NullPointerException at what I think is line 37 in your original file:
if(w.length() >= 10) { // if w is null this would throw Npe
To fix it you may use a List instead:
List<String> words = new ArrayList<String>();
...
words.add( aWord );
Or perhaps you can use a Set if you don't want to have repeated words.

Java File I/O help

I have a problem with my code. I need to do several operations on a log file with this structure:
190.12.1.100 2011-03-02 12:12 test.html
190.12.1.100 2011-03-03 13:18 data.html
128.33.100.1 2011-03-03 15:25 test.html
128.33.100.1 2011-03-04 18:30 info.html
I need to get the number of visits per month, number of visits per page and number of unique visitors based on the IP. That is not the question, I managed to get all three operations working. The problem is, only the first choice runs correctly while the other choices just return values of 0 afterwards, as if the file is empty, so i am guessing i made a mistake with the I/O somewhere. Here's the code:
import java.io.*;
import java.util.*;
public class WebServerAnalyzer {
private Map<String, Integer> hm1;
private Map<String, Integer> hm2;
private int[] months;
private Scanner input;
public WebServerAnalyzer() throws IOException {
hm1 = new HashMap<String, Integer>();
hm2 = new HashMap<String, Integer>();
months = new int[12];
for (int i = 0; i < 12; i++) {
months[i] = 0;
}
File file = new File("webserver.log");
try {
input = new Scanner(file);
} catch (FileNotFoundException fne) {
input = null;
}
}
public String nextLine() {
String line = null;
if (input != null && input.hasNextLine()) {
line = input.nextLine();
}
return line;
}
public int getMonth(String line) {
StringTokenizer tok = new StringTokenizer(line);
if (tok.countTokens() == 4) {
String ip = tok.nextToken();
String date = tok.nextToken();
String hour = tok.nextToken();
String page = tok.nextToken();
StringTokenizer dtok = new StringTokenizer(date, "-");
if (dtok.countTokens() == 3) {
String year = dtok.nextToken();
String month = dtok.nextToken();
String day = dtok.nextToken();
int m = Integer.parseInt(month);
return m;
}
}
return -1;
}
public String getIP(String line) {
StringTokenizer tok = new StringTokenizer(line);
if (tok.countTokens() == 4) {
String ip = tok.nextToken();
String date = tok.nextToken();
String hour = tok.nextToken();
String page = tok.nextToken();
StringTokenizer dtok = new StringTokenizer(date, "-");
return ip;
}
return null;
}
public String getPage(String line) {
StringTokenizer tok = new StringTokenizer(line);
if (tok.countTokens() == 4) {
String ip = tok.nextToken();
String date = tok.nextToken();
String hour = tok.nextToken();
String page = tok.nextToken();
StringTokenizer dtok = new StringTokenizer(date, "-");
return page;
}
return null;
}
public void visitsPerMonth() {
String line = null;
do {
line = nextLine();
if (line != null) {
int m = getMonth(line);
if (m != -1) {
months[m - 1]++;
}
}
} while (line != null);
// Print the result
String[] monthName = {"JAN ", "FEB ", "MAR ",
"APR ", "MAY ", "JUN ", "JUL ", "AUG ", "SEP ",
"OCT ", "NOV ", "DEC "};
for (int i = 0; i < 12; i++) {
System.out.println(monthName[i] + months[i]);
}
}
public int count() throws IOException {
InputStream is = new BufferedInputStream(new FileInputStream("webserver.log"));
try {
byte[] c = new byte[1024];
int count = 0;
int readChars = 0;
while ((readChars = is.read(c)) != -1) {
for (int i = 0; i < readChars; ++i) {
if (c[i] == '\n')
++count;
}
}
return count;
} finally {
is.close();
}
}
public void UniqueIP() throws IOException{
String line = null;
for (int x = 0; x <count(); x++){
line = nextLine();
if (line != null) {
if(hm1.containsKey(getIP(line)) == false) {
hm1.put(getIP(line), 1);
} else {
hm1.put(getIP(line), hm1.get(getIP(line)) +1 );
}
}
}
Set set = hm1.entrySet();
Iterator i = set.iterator();
System.out.println("\nNumber of unique visitors: " + hm1.size());
while(i.hasNext()) {
Map.Entry me = (Map.Entry)i.next();
System.out.print(me.getKey() + " - ");
System.out.println(me.getValue() + " visits");
}
}
public void pageVisits() throws IOException{
String line = null;
for (int x = 0; x <count(); x++){
line = nextLine();
if (line != null) {
if(hm2.containsKey(getPage(line)) == false)
hm2.put(getPage(line), 1);
else
hm2.put(getPage(line), hm2.get(getPage(line)) +1 );
}
}
Set set = hm2.entrySet();
Iterator i = set.iterator();
System.out.println("\nNumber of pages visited: " + hm2.size());
while(i.hasNext()) {
Map.Entry me = (Map.Entry)i.next();
System.out.print(me.getKey() + " - ");
System.out.println(me.getValue() + " visits");
}
}
Any help figuring out the problem would be much appreciated as I am quite stuck.

I didn't read the code thoroughly yet, but I guess you're not setting the read position back to the beginning of the file when you start a new operation. Thus nextLine() would return null.
You should create a new Scanner for each operation and close it afterwards. AFAIK scanner doesn't provide a method to go back to the first byte.
Currently I could also think of 3 alternatives:
Use a BufferedReader and call reset() for each new operation. This should cause the reader to go back to byte 0 provided you didn't call mark() somewhere.
Read the file contents once and iterate over the lines in memory, i.e. put all lines into a List<String> and then start at each line.
Read the file once, parse each line and construct an apropriate data structure that contains the data you need. For example, you could use a TreeMap<Date, Map<Page, Map<IPAdress, List<Visit>>>>, i.e. you'd store the visits per ip address per page for each date. You could then select the appropriate submaps by date, page and ip address.

The reset method of BufferedReader that Thomas recommended would only work if the file size is smaller than the buffer size or if you called mark with a large enough read ahead limit.
I would recommend reading throught the file once and to update your maps and month array for each line. BTW, you don't need a Scanner just to read lines, BufferedReader has a readLine method itself.
BufferedReader br = ...;
String line;
while (null != (line = br.readLine())) {
String ip = getIP(line);
String page = getPage(line);
int month = getMonth(line);
// update hashmaps and arrays
}