小编Hül*_*lya的帖子

给定下面的类和数据结构，我想计算每个连续 3 个元素的计数总和，类似于以下结果：

public class SaleTxn {
    private int id;
    private String txnDate;
    private int amount;

}

数据如下

 id   txnDate        amount
    1    2018-10-10     100
    2    2018-10-11     200
    3    2018-10-12     100
    4    2018-10-13     100
    5    2018-10-14     200
    6    2018-10-15     200
    ... ...

并且窗口大小为 3，表示只是过去 3 个元素的总和，预期结果如下

2018-10-10 ~ 2018-10-12   Total: 100+200+100 = 400
2018-10-13 ~ 2018-10-14   Total: 100+200+200 = 500
...

我在下面有一个列表代码：

List<SaleTxn> myList; //
myList.stream().filter(x -> ??????)
                .mapToInt(SouthboundShareholding::getAmount)
                .sum();

我该如何实施？

考虑这个代码

String[] colours1 = new String[]{"red", "green", "blue"};
String[] colours2 = new String[]{"red", "yellow", "blue"};
String[] colours3 = new String[]{"red", "green", "blue"};

List<String[]> distinct = Stream.of(colours1, colours2, colours3)
        .distinct() // Do something here to compare arrays better
        .collect(Collectors.toList());

我希望distinct列表包含 olny 2 元素colours1和colours2（因为 1 和 3 是等效的）。然而，因为流distinct()方法执行等于比较，它仍然包含所有 3 种颜色数组。我想要一个自定义的不同功能，您可以在其中提供比较器。在这种情况下Objects#deepEquals就足够了。有没有简单的方法来实现这一目标？

class Employee
{
    int id;
     
    String name;
     
    int age;
     
    String gender;
     
    String department;
     
    int yearOfJoining;
     
    double salary;
     
    public Employee(int id, String name, int age, String gender, String department, int yearOfJoining, double salary) 
    {
        this.id = id;
        this.name = name;
        this.age = age;
        this.gender = gender;
        this.department = department;
        this.yearOfJoining = yearOfJoining;
        this.salary = salary;
    }
     
    public int getId() 
    {
        return id;
    }
     
    public String getName() 
    {
        return name;
    }
     
    public int getAge() 
    {
        return age;
    }
     
    public String getGender() 
    { …

有两个表，EntryTable和ExitTable。两者都有相似的列：id, date, time. 当员工打卡时，调用此函数。如果他当天已经打了，他的记录就会被输入到退出表中。否则，将其输入到条目表中。

public int addEntryRecord(String id) {

    try{
        Class.forName("com.mysql.jdbc.Driver");
        Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/Attend","rt","rt");
        Statement stmt = con.createStatement();

        long millis=System.currentTimeMillis();
        java.sql.Date date=new java.sql.Date(millis);
        Date today = new Date();
        Date currentTime = new java.sql.Time(today.getTime());

        stmt.executeQuery("SELECT id from Attend.EntryTable WHERE EntryTable.id ='"+id+"'and   
        EntryTable.DayOf='"+date+"'");                       
        ResultSet rs = stmt.getResultSet();
        System.out.println(rs.next());

        if(rs.next()== true){
            String sql = "INSERT Attend.ExitTable VALUES('"+id+"','"+date+"','"+currentTime+" ')";
            stmt.executeUpdate(sql);
            System.out.println("Good job");
           }

        else{
            String sql ="INSERT Attend.EntryTable VALUES('"+id+"','"+date+"','"+currentTime+"')";
            stmt.executeUpdate(sql);
            System.out.println("Entry noted");
           }
       }catch (Exception e) { …