读取包含名称和数字混合的文件并将它们放入不同的数组中

Question

我正在做 java 介绍 class，我知道这个问题对您来说可能很简单，但我确实需要帮助。所以我试图从一个包含姓名和收入的文件中读取，我想将它们读入不同的数组。

import java.io.*;
import java.util.Scanner;
public class caltax
{
  public static void main (String[] args) 
  {
    String lname[] = new String [12];
    String fname[] = new String [12];
    Double income[] = new Double [12];
    double sincome=0.0;
    int i, count=1;

try 
{
  Scanner infile = new Scanner (new FileInputStream("family.dat"));

  while (infile.hasNextLine())
  {

    lname[12] = infile.next();
    fname[12] = infile.next();
    income[12] = infile.nextDouble();

  }//while

  infile.close();

}//try
catch (Exception e)
{
  System.out.println("Check the file");
}//catch block    

for(i=0;i<12;i++)
{
if (lname[i].equals(lname[i+1]))
{
  count++;
  sincome += income[i];

  //object t is created and constrctor is called 
  taxcalculation t = new taxcalculation (count, lname, fname, sincome);
  t.taxowned();
}//if 

}//for  
 }//main
}//class

Answer 1

为什么要把它们读入不同的数组？这是你的作业要求的吗？一个更好的解决方案是使用您的属性创建一个对象，例如 Employee，然后将每个 Employee 添加到 List<Employee>

如果您询问如何将项目迭代添加到数组中，您需要一个从 0 开始到 array.length - 1 结束的索引。

Answer 2

你快到了。我想这只是拼写错误 lname[12], fname[12],income[12]在那段时间里：

while (infile.hasNextLine())
{
 lname[12] = infile.next();
 fname[12] = infile.next();
 income[12] = infile.nextDouble();

}//同时

假设您只需要文件的前 12 行，它必须如下所示：

int lineIdx =0;
while (infile.hasNextLine() && lineIdx < 12)
{
 lname[lineIdx] = infile.next();
 fname[lineIdx] = infile.next();
 income[lineIdx] = infile.nextDouble();
 lineIdx++;
}//while

已更新：工作逻辑（请阅读代码中的注释）...抱歉延迟。

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

    // 2. Read file:
    while (infile.hasNextLine()) {
        String personLastName = infile.next();
        // skip 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])) {
                    // got it! 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;
            }
        }
    }// while
    // Print results
    System.out.println("Found " + families.length + " families and their taxes");       
    for (int i=0;i < families.length; i++)
    {
        System.out.println("family " + families[i] + " owes $" + taxes[i]);
    }

读取包含名称和数字混合的文件并将它们放入不同的数组中

Read a file with a mix of names and numbers and put them into different arrays

java

arrays

readfile