纸上得来终觉浅，绝知此事要躬行。

LocalDate类的使用

 1 /**
 2      * 让我们手写一个日历吧
 3      * @param args
 4      */
 5     public static void main(String[] args) {
 6         LocalDate date = LocalDate.now();
 7         int month = date.getMonthValue();
 8         int today = date.getDayOfMonth();
 9         
10         date = date.minusDays(today - 1);    // Set to start of month
11         DayOfWeek weekday = date.getDayOfWeek();
12         int value = weekday.getValue();        // 1 = Monday ...7 = Sunday
13         
14         System.out.println("Mon Tue Mon Thu Fri Sat Sun");
15         for(int i = 1; i < value; i ++)
16             System.out.print("    ");
17         while (date.getMonthValue() == month) 
18         {
19             System.out.printf("%3d", date.getDayOfMonth());
20             if (date.getDayOfMonth() == today) 
21                 System.out.print("*");
22             else
23                 System.out.print(" ");
24             date = date.plusDays(1);
25             if (date.getDayOfWeek().getValue() == 1) System.out.println();
26         }
27         if (date.getDayOfWeek().getValue() != 1) {
28             System.out.println();
29         }
30     }

显示效果：

EmployeeTest

 1 public class EmployeeTest {
 2 
 3     public static void main(String[] args) {
 4         // fill the staff array with three Employee objects
 5         Employee[] staff = new Employee[3];
 6         
 7         staff[0] = new Employee("Carl Cracker", 75000, 1987, 12, 15);
 8         staff[1] = new Employee("Harry Hacker", 50000, 1989, 10, 1);
 9         staff[2] = new Employee("Tony Tester", 40000, 1990, 3, 15);
10         
11         // raise everyone's salary by 5%
12         for(Employee e : staff) {
13             e.raiseSalary(5);
14         }
15         
16         // print out information about all Employee objects
17         for(Employee e : staff) {
18             System.out.println("name=" + e.getName()+",salary=" + e.getSalary() + ",hireDay="+ e.getHireDay());
19         }
20     }
21     
22     
23 }
24 
25 class Employee
26 {
27     private String name;
28     private double salary;
29     private LocalDate hireDay;
30     
31     public Employee(String name, double salary, int year, int month, int day) {
32         super();
33         this.name = name;
34         this.salary = salary;
35         this.hireDay = LocalDate.of(year, month, day);
36     }
37 
38     public String getName() {
39         return name;
40     }
41 
42     public double getSalary() {
43         return salary;
44     }
45 
46     public LocalDate getHireDay() {
47         return hireDay;
48     }
49     
50     public void raiseSalary(double byPercent) 
51     {
52         double raise = salary * byPercent / 100;
53         salary += salary;
54     }
55     
56 }

StaticTest

 1 public class StaticTest {
 2     public static void main(String[] args) {
 3         // fill the staff array with three Employee objects
 4         Employee[] staff = new Employee[3];
 5         
 6         staff[0] = new Employee("Tom", 40000);
 7         staff[1] = new Employee("Dick", 60000);
 8         staff[2] = new Employee("Harry", 65000);
 9         
10         // print out information about all Employee objects
11         for (Employee e : staff) {
12             e.setId();
13             System.out.println("name = " + e.getName() + ", id = " + e.getId() +", salary = " + e.getSalary());;
14         }
15         
16         int n = Employee.getNextId();    // call static method
17         System.out.println("Next avaliable id=" + n);
18     }
19     
20 }
21 
22 class Employee
23 {
24     private static int nextId = 1;
25     
26     private String name;
27     private double salary;
28     private int id;
29     
30     public Employee(String name, double salary) {
31         super();
32         this.name = name;
33         this.salary = salary;
34         this.id = 0;
35     }
36 
37     public String getName() {
38         return name;
39     }
40 
41     public double getSalary() {
42         return salary;
43     }
44 
45     public int getId() {
46         return id;
47     }
48     
49     public void setId()
50     {
51         id = nextId;    // set id to next avaliable id
52         nextId++;
53     }
54     
55     public static int getNextId() {
56         return nextId;    // return static field
57     }
58     
59     public static void main(String[] args) {
60         Employee employee = new Employee("Harry", 50000);
61         System.out.println(employee.getName() + " " + employee.getSalary());
62     }
63     
64     
65 }

public class StaticTest {
    public static void main(String[] args) {
        // fill the staff array with three Employee objects
        Employee[] staff = new Employee[3];
        
        staff[0] = new Employee("Tom", 40000);
        staff[1] = new Employee("Dick", 60000);
        staff[2] = new Employee("Harry", 65000);
        
        // print out information about all Employee objects
        for (Employee e : staff) {
            e.setId();
            System.out.println("name = " + e.getName() + ", id = " + e.getId() +", salary = " + e.getSalary());;
        }
        
        int n = Employee.getNextId();    // call static method
        System.out.println("Next avaliable id=" + n);
    }
    
}

class Employee
{
    private static int nextId = 1;
    
    private String name;
    private double salary;
    private int id;
    
    public Employee(String name, double salary) {
        super();
        this.name = name;
        this.salary = salary;
        this.id = 0;
    }

    public String getName() {
        return name;
    }

    public double getSalary() {
        return salary;
    }

    public int getId() {
        return id;
    }
    
    public void setId()
    {
        id = nextId;    // set id to next avaliable id
        nextId++;
    }
    
    public static int getNextId() {
        return nextId;    // return static field
    }
    
    public void raiseSalary(double byPercent) 
    {
        double raise = salary * byPercent / 100;
        salary += raise;
    }
    
    public static void tripleSalary(Employee x) {
        x.raiseSalary(200);
    }
    
    public static void main(String[] args) {
        Employee harry;
        harry = new Employee("Harry", 50000);
        tripleSalary(harry);
        System.out.println(harry.getName() + " " + harry.getSalary());
    }
    
    
}

 1 public class StaticTest {
 2     public static void main(String[] args) {
 3         /**
 4          * Test 1: Methods can't modify numeric parameters
 5          */
 6         System.out.println("Testing tripleValue:");
 7         double percent = 10;
 8         System.out.println("Before: percent=" + percent);
 9         tripleValue(percent);
10         System.out.println("After: percent=" + percent);
11         
12         /**
13          * Test 2: Methods can change the state of object parameters
14          */
15         System.out.println("
Testing tripleSalary");
16         Employee harry = new Employee("Harry", 50000);
17         System.out.println("Before: salary=" + harry.getSalary());
18         tripleSalary(harry);
19         System.out.println("After: salary=" + harry.getSalary());
20         
21         /**
22          * Test 3: Methods can't attach new objects to object parameters
23          */
24         System.out.println("
Testing swap:");
25         Employee a = new Employee("Alice", 70000);
26         Employee b = new Employee("Bob", 70000);
27         System.out.println("Before: a=" + a.getName());
28         System.out.println("Before: b=" + b.getName());
29         swap(a, b);
30         System.out.println("After: a=" + a.getName());
31         System.out.println("After: b=" + b.getName());
32         
33     }
34     
35     public static void tripleValue(double x) {
36         x = 3 * x;
37         System.out.println("End of method: x=" + x);
38     }
39     
40     public static void tripleSalary(Employee x) {
41         x.raiseSalary(200);
42         System.out.println("End of method: salary=" + x.getSalary());
43     }
44     
45     public static void swap(Employee x, Employee y) {
46         Employee temp = x;
47         x = y;
48         y = temp;
49         System.out.println("End of method: x=" + x.getName());
50         System.out.println("End of method: y=" + y.getName());
51     }
52     
53 }
54 
55 class Employee        // simplfied Employee class
56 {    
57     private String name;
58     private double salary;
59     
60     public Employee(String name, double salary) {
61         super();
62         this.name = name;
63         this.salary = salary;
64     }
65 
66     public String getName() {
67         return name;
68     }
69 
70     public double getSalary() {
71         return salary;
72     }
73 
74     
75     public void raiseSalary(double byPercent) 
76     {
77         double raise = salary * byPercent / 100;
78         salary += raise;
79     }
80 }