Java练习题——关于集合的使用，用泛型来处理数据

现有如下员工信息：

工号姓名月薪资

001 杨树苗 4650

002 刘翠花 4280

003 魏巍 6820

004 李宁 5128

005 赵明 3180

请完成如下编码任务：

1）定义一个公共实体类（class Employee）用于描述员工的工号（id）、姓名（name）和薪资（salary）等信息；

2）定义一个公共管理类（class EmployeeManager），使用 ArrayList 泛型集合保存上述列表中的员工信息，并定义公共方法" public void showEmployees() {…}“显示全部员工信息列表；定义公共方法” public float getAvgSalary() {…}“计算并返回全部员工的平均薪资；定义公共方法” public float getStandardDeviation() {…}" 计算并返回全部员工的薪资标准差。

定义Employee类

package itwcn.Demo03;

import java.util.ArrayList;

/**
 * @program: Employee
 * @description:
 * @author: OriginalCoder
 * @createtime:2020/11/22 15:36
 **/

public class Employee {
    
    

    private String id = null;
    private String name = null;
    private float salary = 0;

    public Employee() {
    
    
    }

    public Employee(String id, String name, float salary) {
    
    
        this.setId(id);
        this.setName(name);
        this.setSalary(salary);
    }

    public String getId() {
    
    
        return id;
    }

    public void setId(String id) {
    
    
        this.id = id;
    }

    public String getName() {
    
    
        return name;
    }

    public void setName(String name) {
    
    
        this.name = name;
    }

    public float getSalary() {
    
    
        return salary;
    }

    public void setSalary(float salary) {
    
    
        this.salary = salary;
    }

    /**
     * 显示所有员工基本信息
     */
    public void showEmployees() {
    
    
        System.out.println(this.id + ":" + this.name + ":" + this.salary);
    }

    /**
     * 计算并返回全部员工的平均薪资
     */
    public float getAvgSalary(ArrayList<Employee> arrayList) {
    
    
        float sum = 0;
//        for (int i = 0; i < arrayList.size(); i++) {
    
    
//            sum = arrayList.get(i).getSalary();
//        }
//        return sum/arrayList.size();
        for (Employee ee:arrayList) {
    
    
            sum += ee.getSalary();
        }
        float avg = sum/arrayList.size();
        return avg;
    }

    /**
     * 计算并返回薪资的标准差 Standard Deviation
     */
    /**
     * s为标准差，sqrt表示开根号，x1,x2,x3...是薪资数据，x是平均数，n为数据的个数
     * 计算公式：s = sqrt[[(x1-x)^2+(x2-x)^2+...+(xn-x)^2]/(1/n)]
     * @return 返回标准差
     */
    public float getStandardDeviation(ArrayList<Employee> arrayList) {
    
    
        float deviation = 0;
        float sum = 0,s = 0;
        for (int i = 0; i < arrayList.size(); i++) {
    
    
            sum = sum + (float)Math.pow(arrayList.get(i).getSalary()-getAvgSalary(arrayList),2);
        }
        s = sum / arrayList.size();
         return  (float) Math.sqrt(s);
    }
}

定义EmployeeManager类

package itwcn.Demo03;

import java.util.ArrayList;
import java.util.zip.Deflater;

/**
 * @program: EmployeeManager
 * @description:
 * @author: OriginalCoder
 * @createtime:2020/11/22 15:39
 **/

public class EmployeeManager {
    
    
    public static void main(String[] args) {
    
    
        Employee eA = null;
        ArrayList<Employee> arrayList = new ArrayList<Employee>();
        try {
    
    
            eA = new Employee("001","杨树花",4650);
            arrayList.add(eA);
            eA = new Employee("002","刘翠花",4280);
            arrayList.add(eA);
            eA = new Employee("003","魏巍",6820);
            arrayList.add(eA);
            eA = new Employee("004","李宁",5128);
            arrayList.add(eA);
            eA = new Employee("005","赵明",3180);
            arrayList.add(eA);

        } catch (Exception e) {
    
    
            e.printStackTrace();
        }
        /**
         * 显示所有员工基本信息
         */
        for (Employee ee: arrayList) {
    
    
            ee.showEmployees();
        }
        float avg = eA.getAvgSalary(arrayList);
        float dev = eA.getStandardDeviation(arrayList);
        System.out.println("平均薪资：" + avg);
        System.out.println("薪资标准差：" + dev);

    }
}

上面的代码存在不规范的问题，那么下面的代码是根据规范后，进行修改的代码
建立Employee类

package itwcn.Demo04;

/**
 * @program: Employee
 * @description:
 * @author: OriginalCoder
 * @createtime:2020/11/24 21:13
 **/

/**
 * 实体类：封装员工的基本信息
 */
public class Employee {
    
    
    private String id = null;
    private String name = null;
    private float salary = 0.0F;

    public Employee() {
    
    }

    public Employee(String id, String name, float salary) {
    
    
        this.setId(id);
        this.setName(name);
        this.setSalary(salary);
    }

    public String getId() {
    
    
        return id;
    }
    public void setId(String id) {
    
    
        this.id = id;
    }
    public String getName() {
    
    
        return name;
    }
    public void setName(String name) {
    
    
        this.name = name;
    }
    public float getSalary() {
    
    
        return salary;
    }
    public void setSalary(float salary) {
    
    
        this.salary = salary;
    }

    public void showInfo() {
    
    
        System.out.println(this.id + ":" + this.name + "," + this.salary);
    }

}

建立EmployeeManager类

package itwcn.Demo04;

import java.util.ArrayList;

/**
 * @program: EmployeeManager
 * @description:
 * @author: OriginalCoder
 * @createtime:2020/11/24 21:14
 **/

/**
 *实体类：封装管理员工的方法
 */
public class EmployeeManager {
    
    

    private ArrayList<Employee> employees = null;

    public EmployeeManager() {
    
    
        employees = new ArrayList<Employee>();
    }
    /**
     * 添加员工
     * @param e 一个新员工对象
     * */
    public boolean addEmployee(Employee e) {
    
    
        boolean bR = false;
        if(e!=null) {
    
    
            this.employees.add(e);
            bR = true;
        }
        return bR;
    }

    /**计算并返回员工的平均薪资*/
    public float getAvgSalary() {
    
    
        float fSum = 0.0f;
        for(Employee e:this.employees) {
    
    
            if(e==null) continue;
            fSum = fSum + e.getSalary();
        }
        return fSum/this.employees.size();
    }

    public float getStandardDeviation() {
    
    
        float fAvg = getAvgSalary();
        float fSum = 0.0f;

        for(Employee e:this.employees) {
    
    
            if(e==null) continue;
            fSum = fSum + (float)Math.pow(e.getSalary() - fAvg, 2);
        }
        return (float)Math.sqrt(fSum/(this.employees.size()));
    }

}

建立测试类

package itwcn.Demo04;

/**
 * @program: Test
 * @description:
 * @author: OriginalCoder
 * @createtime:2020/11/24 21:40
 **/

public class Test {
    
    
    public static void main(String[] args) {
    
    
        try {
    
    
            EmployeeManager emA = new EmployeeManager();
            Employee eA = new Employee("001", "张三", 4650);
            emA.addEmployee(eA);
            eA = new Employee("002", "刘翠花", 4280);
            emA.addEmployee(eA);
            eA = new Employee("003", "魏巍", 6820);
            emA.addEmployee(eA);
            eA = new Employee("004", "李宁", 5128);
            emA.addEmployee(eA);
            eA = new Employee("005", "赵明", 3180);
            emA.addEmployee(eA);
//            System.out.println("所有员工信息：" + emA.showInfo());
            System.out.println("平均薪资=" + emA.getAvgSalary());
            System.out.println("标准差=" + emA.getStandardDeviation());
        } catch (Exception e) {
    
    
            e.printStackTrace();
        }
    }
}

Java练习题——关于集合的使用，用泛型来处理数据

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