如何从读取文件中计数不同的数组行号

Question

我在做学校作业。它要求我从一个文件中读取姓名和收入，并将同一家庭中的每一个人放在一起计算家庭税。我已经把人分成了不同的数组，但我很难计算出每个家庭有多少家庭成员。

我正在读取的文件如下所示：

琼斯·拉尔夫39765.45 琼斯玛丽18532.00 琼斯·弗兰克·0.00 汉森约翰63321.00 汉森琳达8765.00 墨菲杰夫53786.75 墨菲尼娜65432.00 墨菲·艾伦·0.00 墨菲·大卫·0.00 西蒙麦克7654.00 西蒙珍妮特44762.00 西蒙·汤姆·0.00

我试着把count++插入到几个地方，但是没有一个地方能给我正确的答案。请帮帮我。

import java.io.*;
import java.util.Scanner;
public class caltax
{
public static void main (String[] args) 
{    

// 1. Define two arrays
String[] families = null;
double[] taxes = null;

// 2. Read file:
 try 
  {
  Scanner infile = new Scanner (new FileInputStream("family.dat"));

while (infile.hasNextLine()) 
{
    String personLastName = infile.next();

    //skip the first name 
    infile.next();

    double personTax = infile.nextDouble();

    // add person data
    if (null == families) 
    {
        // create array for
        families = new String[] { personLastName };
        taxes = new double[] { personTax };
    } 
    else 
    {
        boolean familyExists = false;

        // check existing families
        for (int i = 0; i < families.length; i++) 
        {
            if (personLastName.equals(families[i])) 
            {
                // add personTax to family owed taxes
              taxes[i] += personTax;  

                familyExists = true;
                break;
            }
        }
        if (!familyExists) 
        {
            // Extend arrays to put new family
            // create temp arrays with size+1

            String[] tmpFamilies = new String[families.length + 1];
            double[] tmpTaxes = new double[taxes.length + 1];


            System.arraycopy(families, 0, tmpFamilies, 0, families.length);
            System.arraycopy(taxes, 0, tmpTaxes, 0, taxes.length);

            // set new last elements data
            tmpFamilies[tmpFamilies.length - 1] = personLastName;

            tmpTaxes[tmpTaxes.length - 1] = personTax;

            // replace families and taxes with newly created tmp arrays
            families = tmpFamilies;
            taxes = tmpTaxes;
        }
    }//else

}// while


infile.close();
 }//try

 catch(Exception e) 
{
System.out.println(e.toString());
}//catch block 

// Print results

for (int i=0;i < families.length; i++)
{
    System.out.println("family " + families[i] + " owes $" + taxes[i]);

}
  }
}

Answer 1

只需添加另一个数组

...
int []familyCount = null
if (null == families) 
{
    // create array for
    families = new String[] { personLastName };
    taxes = new double[] { personTax };
    familyCount = new int[] {1};

} 
else 
{
    boolean familyExists = false;

    // check existing families
    for (int i = 0; i < families.length; i++) 
    {
        if (personLastName.equals(families[i])) 
        {
            // add personTax to family owed taxes
          taxes[i] += personTax;  

          familyCount[i] ++;

            familyExists = true;
            break;
        }
    }
    if (!familyExists) 
    {
        // Extend arrays to put new family
        // create temp arrays with size+1

        String[] tmpFamilies = new String[families.length + 1];
        double[] tmpTaxes = new double[taxes.length + 1];
        int[] tmpFamilyCount = new int[familyCount.length+1];


        ...
        System.arraycopy(familyCount, 0, tmpFamilyCount, 0, familyCount.length);

        // set new last elements data 
        ...
        tmpFamilyCount[tmpFamilyCount.length-1] = 1;

        // replace families and taxes with newly created tmp arrays 
        ...
        familyCount = tmpFamilyCount;
    }
}//else

Answer 2

// 1. Define two arrays
...
HashMap<String,Integer> familyMember=null;

    if (null == families) 
    {
        ...
        familyMember = new HashMap();
        familyMember.put(personLastName, new Integer(1));        
    } else {

      ....
       for (int i = 0; i < families.length; i++) 
        {
            if (personLastName.equals(families[i])) 
            {

              int totalPerson = familyMember.get(personLastName).intValue();   
              familyMember.put(personLastName, new Integer(totalPerson));
                .....
            }
        }

       if (!familyExists) 
        {
              ....
              familyMember.put(personLastName, new Integer(1));
        }
    }

  // Print Results

  for (String key : familyMember.keySet()) {
    System.out.println("family " + key + " has " + familyMember.get(key).toString() + " person");
  }

更新-没有HashMap

用有效的拆分方法

// 1. Define two arrays
...
String[] familyMember=null;

    if (null == families) 
    {
        ...
        familyMember = new String[]{personLastName +"-1"};        
    } else {

      ....
       for (int i = 0; i < families.length; i++) 
        {
            if (personLastName.equals(families[i])) 
            {

              int totalPerson = Integer.parseInt(familyMember[i].split("-")[1]);   
              familyMember[i] = families[i]+"-"+String.valueOf(totalPerson+1);
                .....
            }
        }

       if (!familyExists) 
        {
              ....
              String[] tmpFamilyMember = new String[familyMember.length + 1];
             System.arraycopy(familyMember, 0, tmpFamilyMember, 0, familyMember.length);

              tmpFamilyMember[tmpFamilyMember.length - 1] = personLastName+"-1";

           /* **UPDATE** */
           familyMember =  tmpFamilyMember;

        }
    }

  // Print Results

  for (String fam : familyMember) {
    String[] familyWithCount = fam.split("-");
    System.out.println("family " + familyWithCount[0] + " has " + familyWithCount[1] + " person");
  }

结果：

琼斯家族欠58297.45美元

汉森家族欠72086.0美元

墨菲家族欠119218.75美元

西蒙家族欠52416.0美元

琼斯家族有3个人

汉森家有两个人

墨菲家族有4个人

西蒙家有3个人