1 public class Test {2     private String t1 = "这是 Test 的私有属性";3     public String t2 = "这是Test的公有属性";4     protected String t3 = "这是Test受保护的属性";5     String t4 = "这是Test的默认属性";6     private void tese1() {7         System.out.println("我是Test用private修饰符修饰的方法");8     }9     public void tese2() {
10         System.out.println("我是Test用public修饰符修饰的方法");
11     }
12     protected void tese3() {
13         System.out.println("我是Test用protected修饰符修饰的方法");
14     }
15     void tese4() {
16         System.out.println("我是Test无修饰符修饰的方法");
17     }
18 }
19 public class Test2 extends Test{
20     private String e1 = "这是Test2的私有属性";
21     public String e2 = "这是Test2的公有属性";
22     protected String e3 = "这是Test2受保护的属性";
23     String e4 = "这是Test2的默认属性";
24     public void demo1() {
25         System.out.println("我是Test2用public修饰符修饰的方法");
26     }
27     private void demo2() {
28         System.out.println("我是Test2用private修饰符修饰的方法");
29     }
30     protected void demo3() {
31         System.out.println("我是Test2用protected修饰符修饰的方法");
32     }
33     void demo4() {
34         System.out.println("我是Test2无修饰符修饰的方法");
35     }
36 }
37 public class Main {
38     public static void main(String[] args) {
39         Test2 test= new Test2();
40         /*以下设计代码分别调用 demo1 demo2 demo3 demo4 test1 test2 test3 test4方法和t1 t2 t3 t3 e1 e2 e3 e4属性，结合程序运行结果理解继承和权限修饰符的用法与区别*/
41
42          test.demo1();
43          test.demo3();
44          test.demo4();
45
46          test.tese2();
47          test.tese3();
48          test.tese4();
49
50          System.out.println(test.t2);
51          System.out.println(test.t3);
52          System.out.println(test.t4);
53          System.out.println(test.e2);
54          System.out.println(test.e3);
55          System.out.println(test.e4);
56     }
57 }

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){// a quick test to see if the objects are identicalif (this == otherObject) return true;// must return false if the explicit parameter is nullif (otherObject == null) return false;// if the classes don't match, they can't be equalif (getClass() != otherObject.getClass()) return false;// now we know otherObject is a non-null EmployeeEmployee other = (Employee) otherObject;// test whether the fields have identical valuesreturn Objects.equals(name, other.name) && salary == other.salary && Objects.equals(hireDay, other.hireDay);}public int hashCode(){return Objects.hash(name, salary, hireDay); }public String toString(){return getClass().getName() + "[name=" + name + ",salary=" + salary + ",hireDay=" + hireDay+ "]";}
}

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;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;}public boolean equals(Object otherObject){if (!super.equals(otherObject)) return false;Manager other = (Manager) otherObject;// super.equals checked that this and other belong to the same classreturn bonus == other.bonus;}public int hashCode(){return java.util.Objects.hash(super.hashCode(), bonus);}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){// fill the staff array list with three Employee objectsArrayList<Employee> staff = new ArrayList<>();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));// raise everyone's salary by 5%for (Employee e : staff)e.raiseSalary(5);// print out information about all Employee objectsfor (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 _.");      }
}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;
}