201871010117-石欣钰《面向对象程序设计（Java）》第四周学习总结

import java.util.*;


public class StudentTest {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.println("请输入学生人数：");
        int number=in.nextInt();
        Student[] infro=new Student[number];
        for(int i=0;i<number;i++)
        {
            System.out.println("请输入第"+(i+1)+"个人的姓名：");
            String n=in.next();
            System.out.println("请输入第"+(i+1)+"个人的性别：");
            String s=in.next();
            System.out.println("请输入第"+(i+1)+"个人的java成绩：");
            int java=in.nextInt();
            infro[i]=new Student(n,s,java);
        }
        System.out.println("姓名\t性别\tjava成绩\t");
        for (Student e : infro)
             System.out.println(e.getName() + "\t" + e.getSex() + "\t" 
                + e.getJavaScore()+"\t");
    }

}

class Student{
    
    private String name;
    private String sex;
    private int javascore;
    
    public Student(String n,String s,int java){
        this.name=n;
        this.sex=s;
        this.javascore=java;
    }
    
    public String getName()
    {
        return name;
    }
    
    public String getSex()
    {
        return sex;
    }
    
    public int getJavaScore()
    {
        return javascore;
    }
    
}

 1 /**
 2  * This program demonstrates static methods.
 3  * @version 1.02 2008-04-10
 4  * @author Cay Horstmann
 5  */
 6 public class StaticTest
 7 {
 8    public static void main(String[] args)
 9    {
10       // fill the staff array with three Employee objects  (用三个employee对象填充staff数组 )
11       Employee[] staff = new Employee[3];                //构造了一个Employee 数组，并填入三个雇员对象
12 
13       staff[0] = new Employee("Tom", 40000);
14       staff[1] = new Employee("Dick", 60000);
15       staff[2] = new Employee("Harry", 65000);
16 
17       // print out information about all Employee objects    （打印有关所有员工对象的信息 ）
18       for (Employee e : staff)       //调用getName 方法，getId方法和getSalary方法将每个雇员的信息打印出来
19       {
20          e.setId();
21          System.out.println("name=" + e.getName() + ",id=" + e.getId() + ",salary="
22             + e.getSalary());                        
23       }
24 
25       int n = Employee.getNextId(); // calls static method    （通过类名调用静态方法 ）
26       System.out.println("Next available id=" + n);
27    }
28 }
29 
30 class Employee
31 {
32    private static int nextId = 1;     
33 
34    private String name;     //实例域定义
35    private double salary;
36    private int id;
37 
38    public Employee(String n, double s)     //构造器定义
39    {
40       name = n;
41       salary = s;
42       id = 0;
43    }
44 
45    public String getName()        //实例域name的访问器方法
46    {
47       return name;
48    }
49 
50    public double getSalary()    //实例域Salary的访问器方法
51    {
52       return salary;
53    }
54 
55    public int getId()          //实例域Id的访问方法
56    {
57       return id;
58    }
59 
60    public void setId()
61    {
62       id = nextId; // set id to next available id    （将id设置为下一个可用id ）
63       nextId++;
64    }
65 
66    public static int getNextId()        //实例域NextId的访问方法
67    {
68       return nextId; // returns static field    （返回静态字段）
69    }
70 
71    public static void main(String[] args) // unit test    （单元测试 ）
72    {
73       Employee e = new Employee("Harry", 50000);
74       System.out.println(e.getName() + " " + e.getSalary());
75    }
76 }

/**
 * This program demonstrates parameter passing in Java.
 * @version 1.01 2018-04-10
 * @author Cay Horstmann
 */
public class ParamTest
{
   public static void main(String[] args)
   {
      /*
       * Test 1: Methods can‘t modify numeric parameters（方法不能修改数值参数）
       */
      System.out.println("Testing tripleValue:");
      double percent = 10;
      System.out.println("Before: percent=" + percent);
      tripleValue(percent);     //调用方法tripleSalary
      System.out.println("After: percent=" + percent);

      /*
       * Test 2: Methods can change the state of object parameters （方法可以更改对象参数的状态）
       */
      System.out.println("\nTesting tripleSalary:");
      var harry = new Employee("Harry", 50000);
      System.out.println("Before: salary=" + harry.getSalary());
      tripleSalary(harry);               //调用方法tripleSalary
      System.out.println("After: salary=" + harry.getSalary());

      /*
       * Test 3: Methods can‘t attach new objects to object parameters
       */
      System.out.println("\nTesting swap:");
      var a = new Employee("Alice", 70000);    //定义一个类型为var的a，并进行初始化
      var b = new Employee("Bob", 60000);
      System.out.println("Before: a=" + a.getName());
      System.out.println("Before: b=" + b.getName());
      swap(a, b);               //交换函数
      System.out.println("After: a=" + a.getName());
      System.out.println("After: b=" + b.getName());
   }

   public static void tripleValue(double x) // doesn‘t work（不工作）
   {
      x = 3 * x;
      System.out.println("End of method: x=" + x);
   }

   public static void tripleSalary(Employee x) // works
   {
      x.raiseSalary(200);    //x的调用
      System.out.println("End of method: salary=" + x.getSalary());
   }
        //x和y进行交换
   public static void swap(Employee x, Employee y)
   {
      Employee temp = x;
      x = y;
      y = temp;
      System.out.println("End of method: x=" + x.getName());
      System.out.println("End of method: y=" + y.getName());
   }
}

class Employee // simplified Employee class
{
   private String name;     //实例域定义
   private double salary;

   public Employee(String n, double s)  //构造器定义
   {
      name = n;
      salary = s;
   }

   public String getName()     //实例域name的访问器方法
   {
      return name;
   }

   public double getSalary()    ////实例域Salary的访问器方法
   {
      return salary;
   }

   public void raiseSalary(double byPercent)
   {
      double raise = salary * byPercent / 100;
      salary += raise;
   }
}

 1 import java.util.*;
 2 
 3 /**
 4  * This program demonstrates object construction.
 5  * @version 1.02 2018-04-10
 6  * @author Cay Horstmann
 7  */
 8 public class ConstructorTest
 9 {
10    public static void main(String[] args)
11    {
12       // fill the staff array with three Employee objects   (用三个employee对象填充staff数组 )
13       var staff = new Employee[3];
14 
15       staff[0] = new Employee("Harry", 40000);
16       staff[1] = new Employee(60000);
17       staff[2] = new Employee();
18 
19       // print out information about all Employee objects  （打印有关所有员工对象的信息 ）
20       for (Employee e : staff)    //foreach循环
21          System.out.println("name=" + e.getName() + ",id=" + e.getId() + ",salary="
22             + e.getSalary());
23    }
24 }
25 
26 class Employee
27 {
28    private static int nextId;       //静态域nextId
29 
30    private int id;
31    private String name = ""; // instance field initialization（实例字段intialization）
32    private double salary;
33   
34    // static initialization block  （静态intialization块）
35    static
36    {
37       var generator = new Random();
38       // set nextId to a random number between 0 and 9999   （将nextId设置为0到999之间的随机值）
39       nextId = generator.nextInt(10000);
40    }
41 
42    // object initialization block    （对象intialization块）
43    {
44       id = nextId;
45       nextId++;
46    }
47 
48    // three overloaded constructors   //三个重载的构造
49    public Employee(String n, double s)
50    {
51       name = n;
52       salary = s;
53    }
54 
55    public Employee(double s)
56    {
57       // calls the Employee(String, double) constructor   
58       this("Employee #" + nextId, s);   //this用来引用当前对象
59    }
60 
61    // the default constructor      //错误的构造器
62    public Employee()
63    {
64       // name initialized to ""--see above
65       // salary not explicitly set--initialized to 0
66       // id initialized in initialization block
67    }
68 
69    public String getName()   //实例域name的访问器方法
70    {
71       return name;
72    }
73 
74    public double getSalary()  //实例域Salary的访问器方法
75    {
76       return salary;
77    }
78 
79    public int getId()    //实例域Id的访问器方法
80    {
81       return id;
82    }
83 }

import com.horstmann.corejava.*; 
// the Employee class is defined in that package  （Employees类在该包中定义）

import static java.lang.System.*;   //静态导入System类

/**
 * This program demonstrates the use of packages.
 * @version 1.11 2004-02-19
 * @author Cay Horstmann
 */
public class PackageTest
{
   public static void main(String[] args)
   {
      // because of the import statement, we don‘t have to use 
      // com.horstmann.corejava.Employee here
      var harry = new Employee("Harry Hacker", 50000, 1989, 10, 1);

      harry.raiseSalary(5);

      // because of the static import statement, we don‘t have to use System.out here
      out.println("name=" + harry.getName() + ",salary=" + harry.getSalary());
   }
}

package com.horstmann.corejava;    //将类放入包中

// the classes in this file are part of this package   （这个文件中的类就是这个包中的一部分）

import java.time.*;   //java.time包的引入

// import statements come after the package statement   （import语句位于package语句之后）

/**
 * @version 1.11 2015-05-08
 * @author Cay Horstmann
 */
public class Employee
{
   private String name;     //实例域定义
   private double salary;
   private LocalDate hireDay;

   public Employee(String name, double salary, int year, int month, int day)  //构造器定义
   {
      this.name = name;   //this用来引用当前对象
      this.salary = salary;
      hireDay = LocalDate.of(year, month, day);     
   }

   public String getName()    //实例域name的访问器方法
   {
      return name;
   }

   public double getSalary()   //实例域Salary的访问器方法
   {
      return salary;
   }

   public LocalDate getHireDay()   //实例域HireDay的访问器方法
   {
      return hireDay;
   }

   public void raiseSalary(double byPercent)
   {
      double raise = salary * byPercent / 100;
      salary += raise;
   }
}