Java字符串数组到长数组的转换
对java和数组来说仍然是新手。我很难将CSV中的数据读入字符串数组，并将其转换为只能处理数字的长数组。我这样做是为了最终能够找到最大值/最小值、平均值等。在下面的第二幅图中，您可以看到我将数据从字符串数组打印到屏幕上。我的CSV有20列和21行。当我尝试解析和转换时，我的数组打印了部分数据，并用0填充了大部分索引。我正在尝试找出转换是否错误，或者是否是筛选数组索引的for循环存在问题
import java.io.FileReader;
import java.io.BufferedReader;
import java.util.Scanner;
import java.io.IOException;
import java.util.Arrays;
import java.io.FileNotFoundException;
import java.lang.Math;
public class USCrimes {
int year;
long population;
long violentCrime;
double violentCrimeRate;
long murderManslaughter;
double murderManslaughterRate;
long rape;
double rapeRate;
long robbery;
double robberyRate;
long aggravatedAssault;
double aggravatedAssaultRate;
long propertyCrime;
double propertyCrimeRate;
long burglary;
double burglaryRate;
long larcenyTheft;
double larcenyTheftRate;
long motorVehicleTheft;
double motorVehicleTheftRate;
String fileName= "C:/Users/micha/OneDrive/Documents/College/SEP 18/Crime.csv";
String crimeArray[];
//getter and setter methods for variables between lines 17 - 36
public void setYear(int year) {
this.year = year;
}
public int getYear() {
return year;
}
public long getViolentCrime() {
return violentCrime;
}
public void setViolentCrime(long violentCrime) {
this.violentCrime = violentCrime;
}
public double getViolentCrimeRate() {
return violentCrimeRate;
}
public void setViolentCrimeRate(double violentCrimeRate) {
this.violentCrimeRate = violentCrimeRate;
}
public long getMurderManslaughter() {
return murderManslaughter;
}
public void setMurderManslaughter(long murderManslaughter) {
this.murderManslaughter = murderManslaughter;
}
public double getMurderManslaughterRate() {
return murderManslaughterRate;
}
public void setMurderRate(double murderManslaughterRate) {
this.murderManslaughterRate = murderManslaughterRate;
}
public long getRape() {
return rape;
}
public void setRape(Long rape) {
this.rape = rape;
}
public double getRapeRate() {
return rapeRate;
}
public void setRapeRate(double rapeRate) {
this.rapeRate = rapeRate;
}
public long getRobbery() {
return robbery;
}
public void setRobbery(long robbery) {
this.robbery = robbery;
}
public double getRobberyRate() {
return robberyRate;
}
public void setRobberyRate(float robberyRate) {
this.robberyRate = robberyRate;
}
public long getAggravatedAssault() {
return aggravatedAssault;
}
public void setAggravatedAssault(long aggravatedAssault) {
this.aggravatedAssault = aggravatedAssault;
}
public double getAggravatedAssaultRate() {
return aggravatedAssaultRate;
}
public void setAggravatedAssaultRate(double aggravatedAssaultRate) {
this.aggravatedAssaultRate = aggravatedAssaultRate;
}
public long getPropertyCrime() {
return propertyCrime;
}
public void setPropertyCrime(long propertyCrime) {
this.propertyCrime = propertyCrime;
}
public double getPropertyCrimeRate() {
return propertyCrimeRate;
}
public void setPropertyCrime(double propertyCrimeRate) {
this.propertyCrimeRate = propertyCrimeRate;
}
public long getBurglary() {
return burglary;
}
public void setBurglary(long burglary) {
this.burglary = burglary;
}
public double getBurglaryRate() {
return burglaryRate;
}
public void setBurglaryRate(double burglaryRate) {
this.burglaryRate = burglaryRate;
}
public long getLarcernyTheft() {
return larcenyTheft;
}
public void setLarcenyTheft(long larcenyTheft) {
this.larcenyTheft = larcenyTheft;
}
public double getLarcernyTheftRate() {
return larcenyTheftRate;
}
public void setLarcenyTheftRate(double larcenyTheftRate) {
this.larcenyTheftRate = larcenyTheftRate;
}
public long getMotorVehicleTheft() {
return motorVehicleTheft;
}
public void setMotorVehicleTheft(long motorVehicleTheft) {
this.motorVehicleTheft = motorVehicleTheft;
}
public double getMotorVehicleTheftRate() {
return motorVehicleTheftRate;
}
public void setMotorVehicleTheftRate(double motorVehicleTheftRate) {
this.motorVehicleTheftRate = motorVehicleTheftRate;
}
public String getFileName() {
return fileName;
}
public void setFileName(String fileName) {
this.fileName = fileName;
//end getter and setter methods for variables between lines 17 - 36
}
}
class TestUSCrime{
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
USCrimes newUSCrimes = new USCrimes();
long startTime = System.currentTimeMillis();
BufferedReader br = null;
String csvComma = ",";
String line = "";
int index = 0;
System.out.println("********** Welcome to the USCrime Statistical Application **************************\n");
System.out.println("Which US Crime file would you like to use?\n");
String userInput = input.nextLine();
input.close();
//printing the menu for user selection
System.out.println("Please enter the number for the question you would like answered. At any time, enter Q to quit the program:\n");
System.out.println("1. What were the percentages in population growth for each consecutive year from 1994 ñ 2013?");
System.out.println("2. What year was the Murder rate the highest?");
System.out.println("3. What year was the Murder rate the lowest?");
System.out.println("4. What year was the Robbery rate the highest?");
System.out.println("5. What year was the Robbery rate the lowest?");
System.out.println("6. What was the total percentage change in MotorVehicle Theft between 1998 and 2012?");
System.out.println("7. What year was the Violent Crime rate the highest?");
System.out.println("8. What year was the Violent Crime rate the ");
System.out.println("");
//setting the filename for user defined input
newUSCrimes.setFileName(userInput);
try {
br = new BufferedReader(new FileReader(newUSCrimes.fileName));
while ((line = br.readLine()) != null) {
String [] crimesArray = line.split(csvComma);
long[] crimesArrayNumbers = new long[crimesArray.length];
System.out.println(crimesArray[0] + " , "+ crimesArray[1] + " , " + crimesArray[2] + " , " + crimesArray[3]);
for(int i = 0; i < crimesArrayNumbers.length;i++)
{
try
{
crimesArrayNumbers[index] = Long.parseLong(crimesArray[i]);
index++;}
catch (IndexOutOfBoundsException ioob){
}
catch (NumberFormatException e){
}
}//end for loop
crimesArrayNumbers = Arrays.copyOf(crimesArrayNumbers, index);
//System.out.println(Arrays.toString(crimesArrayNumbers));
}//end try
System.out.println();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
System.out.println("Thank you for trying the US Crimes Statistics Program.");
//calculating the elapsed time using milliseconds and subsequently dividing by 1000.
long endTime = System.currentTimeMillis();;
long timeElapsed = endTime - startTime;
System.out.println("Elapsed time in seconds was: " + (timeElapsed / 1000));
if (args.length != 1) {
System.out.println("Usage: \"java TestUSCrime Crime.csv");
return;
} // end if
} //end main
} //end TestUSCrimes
![Output for the long[] crimeArrayNumbers. Most of my values are 0](https://i.stack.imgur.com/Xydse.png)
![Output for String [] crimeArray from the CSV data](https://i.stack.imgur.com/k54H6.png)
# 1 楼答案
您不会在主循环内重置索引变量。加
在这条线之前