徐思201771010132《面向对象程序设计（java）》第七周学习总结(代码片段)

public class TEST1 
    private String t1 = "这是TEST1的私有属性";
    public String t2 = "这是TEST1的公有属性";
    protected String t3 = "这是TEST1受保护的属性";
    String t4 = "这是TEST1的默认属性";
    private void test1() 
        System.out.println("我是TEST1用private修饰符修饰的方法");
    
    public void test2() 
        System.out.println("我是TEST1用public修饰符修饰的方法");
    
    protected void test3() 
        System.out.println("我是TEST1用protected修饰符修饰的方法");
    
    void test4() 
        System.out.println("我是TEST1无修饰符修饰的方法");
    

public class TEST2 extends TEST1
    private String e1 = "这是TEST2的私有属性";
    public String e2 = "这是TEST2的公有属性";
    protected String e3 = "这是TEST2受保护的属性";
    String e4 = "这是TEST2的默认属性";
    public void demo1() 
        System.out.println("我是TEST2用public修饰符修饰的方法");
    
    private void demo2() 
        System.out.println("我是TEST2用private修饰符修饰的方法");
    
    protected void demo3() 
        System.out.println("我是TEST2用protected修饰符修饰的方法");
    
    void demo4() 
        System.out.println("我是TEST2无修饰符修饰的方法");
    

public class Main 
    public static void main(String[] args) 
        TEST2 test2 = new TEST2();
        /*在下面分别调用 demo1 demo2 demo3 demo4 test1 test2 test3 test4方法
        和 t1 t2 t3 t4 e1 e2 e3 e4属性，好好理解继承和权限修饰符的用法与区别*/
        //demo2 test1 t1 e1是用private修饰符修饰的，不能被访问
        test2.demo1();
        test2.demo3();
        test2.demo4();
        test2.test2();
        test2.test3();
        test2.test4();
        System.out.println(test2.t2);
        System.out.println(test2.t3);
        System.out.println(test2.t4);
        System.out.println(test2.e2);
        System.out.println(test2.e3);
        System.out.println(test2.e4);
    

package equals;

/**
 * This program demonstrates the equals method.
 * @version 1.12 2012-01-26
 * @author Cay Horstmann
 */
public class EqualsTest

   public static void main(String[] args)
   
      Employee alice1 = new Employee("Alice Adams", 75000, 1987, 12, 15);
      Employee alice2 = alice1;
      Employee alice3 = new Employee("Alice Adams", 75000, 1987, 12, 15);
      Employee bob = new Employee("Bob Brandson", 50000, 1989, 10, 1);

      System.out.println("alice1 == alice2: " + (alice1 == alice2));

      System.out.println("alice1 == alice3: " + (alice1 == alice3));

      System.out.println("alice1.equals(alice3): " + alice1.equals(alice3));

      System.out.println("alice1.equals(bob): " + alice1.equals(bob));

      System.out.println("bob.toString(): " + bob);

      Manager carl = new Manager("Carl Cracker", 80000, 1987, 12, 15);
      Manager boss = new Manager("Carl Cracker", 80000, 1987, 12, 15);
      boss.setBonus(5000);
      System.out.println("boss.toString(): " + boss);
      System.out.println("carl.equals(boss): " + carl.equals(boss));
      System.out.println("alice1.hashCode(): " + alice1.hashCode());
      System.out.println("alice3.hashCode(): " + alice3.hashCode());
      System.out.println("bob.hashCode(): " + bob.hashCode());
      System.out.println("carl.hashCode(): " + carl.hashCode());
   

package equals;

import java.time.*;
import java.util.Objects;

public class Employee

   private String name;
   private double salary;
   private LocalDate hireDay;

   public Employee(String name, double salary, int year, int month, int day)
   
      this.name = name;
      this.salary = salary;
      hireDay = LocalDate.of(year, month, day);
   

   public String getName()
   
      return name;
   

   public double getSalary()
   
      return salary;
   

   public LocalDate getHireDay()
   
      return hireDay;
   

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

   public boolean equals(Object otherObject)
   
      // 快速测试以确定对象是否相同
      if (this == otherObject) return true;//检测this与otherObject是否引用同一个对象

      // 如果显示参数为null，则返回false
      if (otherObject == null) return false;//检测otherObject是否为null，如果为null，返回false 

      //如果类不匹配，他们不可能相等
      if (getClass() != otherObject.getClass()) return false;//比较this与otherObject是否属于同一个类。如果equals的语义在每个子类中有所改变，就使用getClass检测
      
      // 现在我们知道其他的对象是一个非空Employee
      Employee other = (Employee) otherObject;//将otherObject转换为相应的类类型变量

      // 检测是否有相同的值
      return Objects.equals(name, other.name) && salary == other.salary && Objects.equals(hireDay, other.hireDay);//Objects.quals方法防备参数可能为null的情况
   

   public int hashCode()
   
      return Objects.hash(name, salary, hireDay); 
   
//Employee类中的toString方法的实现。通过调用getClass().getName()获得类名的字符串
   public String toString()
   
      return getClass().getName() + "[name=" + name + ",salary=" + salary + ",hireDay=" + hireDay
            + "]";
   

package equals;

public class Manager extends Employee

   private double bonus;

   public Manager(String name, double salary, int year, int month, int day)
   
      super(name, salary, year, month, day);
      bonus = 0;
   

   public double getSalary()
   
      double baseSalary = super.getSalary();
      return baseSalary + bonus;
   

   public void setBonus(double bonus)
   
      this.bonus = bonus;
   
//调用超类的equals
   public boolean equals(Object otherObject)
   
      if (!super.equals(otherObject)) return false;
      Manager other = (Manager) otherObject;
      // super.equals检查这个和其他属于同一个类
      return bonus == other.bonus;
   

   public int hashCode()
   
      return java.util.Objects.hash(super.hashCode(), bonus);
   
//toString方法也可以供子类调用
   public String toString()
   
      return super.toString() + "[bonus=" + bonus + "]";//
   

package arrayList;

import java.util.*;

/**
 * This program demonstrates the ArrayList class.
 * @version 1.11 2012-01-26
 * @author Cay Horstmann
 */
public class ArrayListTest

   public static void main(String[] args)
   
      //用三个雇员Employee对象ArrayList填充人员数组列表<Employee>
      ArrayList<Employee> staff = new ArrayList<>();//构造和声明一个保存Employee对象的数组列表。结合new操作符使用菱形语法，如果赋值给一个变量，或传递到某种方法，
或者从某个方法返回，编译器会检查这个变量、参数或方法的泛型类型，然后将这个类型放在<>中。
//使用add方法将雇员对象添加到数组列表中
      staff.add(new Employee("Carl Cracker", 75000, 1987, 12, 15));
      staff.add(new Employee("Harry Hacker", 50000, 1989, 10, 1));
      staff.add(new Employee("Tony Tester", 40000, 1990, 3, 15));

      // 提高每人5%的工资
      for (Employee e : staff)
         e.raiseSalary(5);

      // 输出关于所有Employee对象的信息
      for (Employee e : staff)
         System.out.println("name=" + e.getName() + ",salary=" + e.getSalary() + ",hireDay="
               + e.getHireDay());
   

package arrayList;

import java.time.*;

public class Employee

   private String name;
   private double salary;
   private LocalDate hireDay;

   public Employee(String name, double salary, int year, int month, int day)
   
      this.name = name;
      this.salary = salary;
      hireDay = LocalDate.of(year, month, day);
   

   public String getName()
   
      return name;
   

   public double getSalary()
   
      return salary;
   

   public LocalDate getHireDay()
   
      return hireDay;
   

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

package enums;

import java.util.*;

/**
 * This program demonstrates enumerated types.
 * @version 1.0 2004-05-24
 * @author Cay Horstmann
 */
public class EnumTest
  
   public static void main(String[] args)
     
      Scanner in = new Scanner(System.in);
      System.out.print("Enter a size: (SMALL, MEDIUM, LARGE, EXTRA_LARGE) ");
      String input = in.next().toUpperCase();
      Size size = Enum.valueOf(Size.class, input);
      System.out.println("size=" + size);
      System.out.println("abbreviation=" + size.getAbbreviation());
      if (size == Size.EXTRA_LARGE)
         System.out.println("Good job--you paid attention to the _.");      
   

//枚举类型
enum Size

   SMALL("S"), MEDIUM("M"), LARGE("L"), EXTRA_LARGE("XL");

   private Size(String abbreviation)  this.abbreviation = abbreviation; 
   public String getAbbreviation()  return abbreviation; 

   private String abbreviation;