我正在做学校作业。它要求我从文件中阅读姓名和收入，并将每个家庭中的每个人放在一起以计算家庭的税款。我已经把人们放到了不同的阵列中，但是我很难计算每个家庭有多少家人。
我从看起来像这样阅读的文件：
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
Murphy Jeff 53786.75
Murphy Nina 65432.00
Murphy Ellen 0.00
墨菲大卫0.00
Simon Mike 7654.00
Simon Janet 44762.00
Simon Tom 0.00
我试图将计数 插入几个地方，但它们都没有给我正确的答案。请在这里帮助我。
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]);
}
}
}
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
// 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 - 不使用HashMap
使用有用的 split 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：
家庭琼斯欠$ 58297.45
家庭汉森欠$ 72086.0
家庭墨菲欠$ 119218.75
Family Simon欠$ 52416.0
家庭琼斯有3人
家庭汉森有2人
家庭墨菲有4人
家庭西蒙有3人