java - 将txt文件读入数组，然后找到工资的最小值、最大值和平均值

Question

看起来本周是此类问题的一周。在读完所有新书和几本旧书后，我的困惑也没有减少!

我有一个包含 5 名员工的文本文件，每个员工的名字下方都列出了 10 个薪资值。我要读取这个文件，找到并显示每个人的员工姓名、最低工资、最高工资和平均工资。我必须有 3 个循环:一个用于控制读取文件，一个用于将数据加载到数组中，一个用于进行计算。我必须在一行上打印每个人的信息，并且我必须允许小数四舍五入到小数点后两位，显然使用我从未听说过的 Math.round!

我很尴尬地向您展示我拥有的困惑代码，因为它并不多，但在阅读完我拥有的所有代码后，我不知道我是否已经正确开始。我不知道我是否有正确的想法如何继续。感谢您的帮助。

更新代码:再次!

    import javax.swing.*;
import java.io.*;
public class MinMaxSalary3
{
    public static void main(String args[])throws Exception
    {
        // Declare input file to be opened.
        FileReader fr = new FileReader ("salary.dat");
        BufferedReader br = new BufferedReader (fr);
        //General Declarations
        final String TITLE = "Employee's Salary Report";
        String employeeName, salaryString;
        double avgSalary=0.0;
        double totalSalary = 0.0;
        double sum = 0.0; 
        // Declare Named Constant for Array.
        final int MAX_SAL = 10;     
        // Declare array here.
        int salary[] = new int[MAX_SAL];

         System.out.println (TITLE);
            while ((employeeName = br.readLine()) != null)
            {
               System.out.print ("" + employeeName);


        // Use this integer variable as your loop index.
                int loopIndex;                  
        // Assign the first element in the array to be the minimum and the maximum.
                double minSalary = salary[1];
               double maxSalary = salary[1]; 
        // Start out your total with the value of the first element in the array.
                sum = salary[1]; 
            // Write a loop here to access array values starting with number[1]
                for (loopIndex = 1; loopIndex < MAX_SAL ;loopIndex++)
        // Within the loop test for minimum and maximum salaries.
                {
                    if  (salary[loopIndex] < minSalary)
                    {
                        minSalary = salary[loopIndex];

                   if (salary[loopIndex] > maxSalary)

                    maxSalary = salary[loopIndex];


                    }   

                        {
            // Also accumulate a total of all salaries.
                       sum += sum; 
          // Calculate the average of the 10 salaries.
                            avgSalary = sum/MAX_SAL;
                        }
            //  I know I need to close the files, and end the while loop and any other loops. I just can't think that far right now. 
            }
            {
        // Print the maximum salary, minimum salary, and average salary.
            System.out.println ("Max Salary" + maxSalary);  
            System.out.println ("Min Salary" + minSalary); 
            System.out.println ("Avg Salary" + avgSalary); 
            }


        System.exit(0);
    }
  }
}

Answer 1

I must have 3 loops: One to control reading the file, one to lad the data into the array, and one to do the calculations.

我在下面写的内容现在对您来说可能更加晦涩难懂，但如果您通过了这门类(class)，了解这些内容可能会很有用。

另一种看待这个问题的方法是更加面向对象和更好的分解:您需要一个对象来保存数据、执行计算并呈现输出。如何获取这些数据并不重要。今天是文件；下次可能是 HTTP 请求。

从 Employee 对象开始。我故意遗漏了很多你必须填写并弄清楚的细节:

package model;

public class Employee {
    private String name;
    private double [] salaries;

    public Employee(String name, int numSalaries) { 
        this.name = name;
        this.salaries = new double[numSalaries];
    }

    public double getMinSalary() {
        double minSalary = Double.MAX_VALUE;
        // you fill this in.
        return minSalary;
    };

    public double getMaxSalary() {
        double maxSalary = Double.MIN_VALUE;
        // you fill this in.
        return maxSalary;
    }

    public double getAveSalary() {
        public aveSalary = 0.0;
        if (this.salaries.length > 0) {
            // you fill this in.
        }
        return aveSalary;
    }
}

这种方法的优点在于您可以单独测试它，而不必担心有关文件 I/O 的所有废话。正确处理这个物体，把它放在一边，然后处理下一个物体。最终，当您将所有这些较小的部分组装在一起时，您将获得一个干净的解决方案。

使用 JUnit 在没有文件 I/O 的情况下进行测试:

package model;

public class EmployeeTest {
    @Test
    public void testGetters() {
        double [] salaries = { 10000.0, 20000.0, 30000.0, 40000.0 };
        Employee testEmployee = new Employee("John Q. Test", salaries);
        Assert.assertEquals("John Q. Test", testEmployee.getName());
        Assert.assertEquals(10000.0, testEmployee.getMinSalary(), 1.0e-3);
        Assert.assertEquals(40000.0, testEmployee.getMaxSalary(), 1.0e-3);
        Assert.assertEquals(25000.0, testEmployee.getMinSalary(), 1.0e-3);     
    }
}