Java - 字符串数组转换为长数组 [关闭]

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对 Java 和数组还是新手。 我很难将 CSV 中的数据读取到 String 数组中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可以尝试找到最大值/最小值、平均值等。在下面的第二张图中，您可以看到我将数据从 String 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。 我试图弄清楚它是否转换错误，或者它是否与我筛选数组索引的 for 循环有关。

 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

Answer 1

您不会在主循环内重置索引变量。 添加

index=0;

在这条线之前

for(int i = 0; i < crimesArrayNumbers.length;i++)