in java project having issues displaying languages pulled database , stored in arraylist read in readcountry class. question why wont display languages , why tell me readcountrylanguages method in not locally used?
import java.util.arraylist; import java.util.list; public class country { private int id; private string name; private long population; private double medianage; private list<string> languages; /** * country class */ public country(int id, string name, long population, double medianage) { this.id = id; this.name = name; this.population = population; this.medianage = medianage; this.languages = new arraylist<>(); } public int getid() { return id; } public string getname() { return name; } public long getpopulation() { return population; } public double getmedianage() { return medianage; } public void addlanguage (string language) { languages.add(language); } public list<string> getlanguages() { return languages; } } public class readcountrydb { private static final string db_name = "countries"; private static final string private static final string country_table_name = "country"; private static final string username = "2bjexample"; private static final string password = "tnedutsh332"; private list<country> countries; public readcountrydb() { connection connection = null; statement sqlstatement = null; try { connection = drivermanager.getconnection(db_url, username, password); sqlstatement = connection.createstatement(resultset.type_scroll_sensitive, resultset.concur_read_only); countries = readcountries(sqlstatement); } catch (sqlexception e) { system.err.println("error: " + e.getmessage()); e.printstacktrace(); } { close(sqlstatement); close(connection); } } private list<country> readcountries(statement sqlstatement) throws sqlexception { list<country> countries = new arraylist<country>(); resultset resultset = sqlstatement.executequery("select * " + country_table_name); while (resultset.next()) { countries.add(new country(resultset.getint("id"), resultset.getstring("name"), resultset.getlong("population"), resultset.getdouble("medianage"))); } return countries; } private list<string>readcountrylanguages(statement sqlstatement) throws sqlexception { list<string> languages = new arraylist<>(); resultset resultset = sqlstatement.executequery("select language country_language"); while (resultset.next()) { languages.add(new string(resultset.getstring("countryid"))); } return languages; } /** * * @param sqlstatement */ private void close(statement sqlstatement) { if (sqlstatement != null) { try { sqlstatement.close(); } catch (sqlexception e) { } } } /** * * @param connection */ private void close(connection connection) { if (connection != null) { try { connection.close(); } catch (sqlexception e) { } } } /** * @return list of countries read country database */ public list<country> getcountries() { return countries; } }
import java.util.list; /** * countrymain class */ public class countrymain { public static void main(string[] args) { readcountrydb rcdb = new readcountrydb(); list<country> countries = rcdb.getcountries(); (country firstcountry : countries) { system.out.println("first country:"); system.out.println("name: " + firstcountry.getname() + " population: " + firstcountry.getpopulation() + " language: " + firstcountry.getlanguages() + " median age: " + firstcountry.getmedianage()); } } }
based on code posted, readcountrylanguages() method never gets called inside country.java. ide alerting of this, since don't want building .class files containing code not using.
the readcountrylanguages() method appears obtain list of languages database. wanted call method @ point forgot to.
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