I have two CSV files, one "crimeUSA.csv" with the headers state, city, population etc. and one StatesAbbreviations with the headers states, abbrev . First I read the "crimeUSA.csv" file and create CityCrime objects.
Instead of using the state in this file, I want to match it with the state in the StatesAbbreviations file and set the state as the appropriate abbreviation value instead. I previously had the states and matching abbreviations hardcoded in the setter for state but I have removed it as was pretty long and ugly. In the readCrimeData() method is where I am creating the instances of the CityCrime object, so crime.setState(stats[1]); is commented out as I do not wanted the state/abbreviation hardcoded anymore.
This is the StartApp class:
public static void main(String[] args) {
try {
CityCrime.readAbbrevData();
readCrimeData("crimeUSA.csv");
System.out.println("Total cities read: " + getTotalCities());
showMenu();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* Reads the crime data for each city from entered file
* Adds the CityCrime objects to the crimes ArrayList
*/
public static void readCrimeData(String fromFile) {
File file = new File(fromFile);
FileReader fileReader;
BufferedReader bufferedReader;
String crimeInfo;
String[] stats;
try {
fileReader = new FileReader(file);
bufferedReader = new BufferedReader(fileReader);
crimeInfo = bufferedReader.readLine();
crimeInfo = bufferedReader.readLine();
do {
CityCrime crime = new CityCrime(); // Default constructor
stats = crimeInfo.split(",");
{
if (stats[0] != null) {
crime.setCity(stats[0]);
}
if (stats[1] != null) {
crime.setAbbreviation(stats[1]);
//crime.setState(stats[1]);
}
if (stats[2] != null) {
if (Integer.parseInt(stats[2]) >= 0) {
crime.setPopulation(Integer.parseInt(stats[2]));
}
}
if (stats[3] != null) {
if (Integer.parseInt(stats[3]) >= 0) {
crime.setMurder(Integer.parseInt(stats[3]));
}
}
if (stats[4] != null) {
if (Integer.parseInt(stats[4]) >= 0) {
crime.setRobbery(Integer.parseInt(stats[4]));
}
}
if (stats[5] != null) {
if (Integer.parseInt(stats[5]) >= 0) {
crime.setAssault(Integer.parseInt(stats[5]));
}
}
if (stats[6] != null) {
if (Integer.parseInt(stats[6]) >= 0) {
crime.setBurglary(Integer.parseInt(stats[6]));
}
}
if (stats[7] != null) {
if (Integer.parseInt(stats[7]) >= 0) {
crime.setLarceny(Integer.parseInt(stats[7]));
}
}
if (stats[8] != null) {
if (Integer.parseInt(stats[8]) >= 0) {
crime.setMotorTheft(Integer.parseInt(stats[8]));
}
}
crime.setTotalCrimes(Integer.parseInt(stats[3]), Integer.parseInt(stats[4]), Integer.parseInt(stats[5]), Integer.parseInt(stats[6]), Integer.parseInt(stats[7]), Integer.parseInt(stats[8]));
}
crimes.add(crime);
System.out.println(crime);
crimeInfo = bufferedReader.readLine();
} while (crimeInfo != null);
fileReader.close();
bufferedReader.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (NumberFormatException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
public static void readAbbrevData() {
File file = new File("StatesAbbreviations.csv");
var stateToAbbreviation = new HashMap<String, String>();
try (BufferedReader bufferedReader = new BufferedReader(new FileReader(file))) {
String abbrevInfo;
while ((abbrevInfo = bufferedReader.readLine()) != null) {
String[] stats = abbrevInfo.split(",");
// stats[0] may be empty, but never null, no check required
stateToAbbreviation.put(stats[0], stats[1]);
}
} catch (IOException e) {
throw new RuntimeException("Could not read state / abbreviations from CSV file", e);
}
for (String key: stateToAbbreviation.keySet()){
System.out.println(key +" = "+stateToAbbreviation.get(key));
}
}
The CityCrime class:
public static void main(String[] args) {
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
public int getPopulation() {
return population;
}
public void setPopulation(int population) {
this.population = population;
}
//etc
@SuppressWarnings("null")
public String setAbbreviation(String state) {
return stateToAbbreviation.getOrDefault(state,"UNKNOWN");
}
My aim is to have a setAbbreviation, so it takes the state value of the CityCrime CSV, basically matches it with the state in the StatesAbbreviation class, and sets it as the matching abbreviation.
As you can probably tell, I am relatively new to Java, so please try and explain in simple terms as possible to help my understanding.
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Answer
Change the return type of your readAbbrevData method from void to Map<String,String> to return a map instead of just printing it out to console, i.e:
public static Map<String,String> readAbbrevData() {
File file = new File("StatesAbbreviations.csv");
var stateToAbbreviation = new HashMap<String, String>();
// ....
return stateToAbbreviation
}
Call the above method before processing your crime data file in your readCrimeData method to get the map and use it to set your abrivations
public static void readCrimeData(String fromFile) {
Map<String,String> myMap = readAbbrevData();
File file = new File(fromFile);
....
if (stats[1] != null) {
crime.setAbbreviation(myMap.get(stats[1]));
//crime.setState(stats[1]);
}