java - 如果 util.date 的日期是个位数，则按 util.date 字段排序列表无法正确排序

Question

下面是我的 pojo 类

import java.util.Date;
public class SortingDate implements Comparable<SortingDate> {

    private Date date;
    private String type;
    private String motion;
    private Date startDateTime;
    private Date endDateTime;
    public Date getDate() {
        return date;
    }
    public void setDate(Date date) {
        this.date = date;
    }
    public String getType() {
        return type;
    }
    public void setType(String type) {
        this.type = type;
    }

    public String getMotion() {
        return motion;
    }
    public void setMotion(String motion) {
        this.motion = motion;
    }
    public Date getStartDateTime() {
        return startDateTime;
    }
    public void setStartDateTime(Date startDateTime) {
        this.startDateTime = startDateTime;
    }
    public Date getEndDateTime() {
        return endDateTime;
    }
    public void setEndDateTime(Date endDateTime) {
        this.endDateTime = endDateTime;
    }

    @Override
    public int compareTo(SortingDate o) {
        return getStartDateTime().compareTo(o.getStartDateTime());
    }   
}

我正在尝试按 StartDateTime 字段升序排序。当我尝试输入样本日期 ex:2015-07-01 时，如果我的日期是两位数，则不会对此实例进行排序，它会正确排序。

我的实现如下:

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.List;

public class SortingDateImpl {
public static void main(String[] args) {
    DateFormat formatter = new SimpleDateFormat("yyyy-mm-dd");

    List<SortingDate> list = new ArrayList<>();
    try{
    SortingDate MO1 = addInstance("1-10-15","DAY","AREWR-DEP",formatter.parse("2015-06-10"),formatter.parse("2015-06-11"));
    SortingDate MO21 = addInstance("1-10-15","DAY","ARERR",formatter.parse("2015-06-13"),formatter.parse("2015-06-11"));
    SortingDate MO22 = addInstance("1-10-15","Evening","DSAEP",formatter.parse("2015-06-14"),formatter.parse("2015-06-11"));
    SortingDate MO31 = addInstance("1-10-15","Evening","AASDRR",formatter.parse("2015-06-23"),formatter.parse("2015-06-11"));
    SortingDate MO32 = addInstance("1-10-15","Night","AADSDRR",formatter.parse("2015-06-15"),formatter.parse("2015-06-11"));
    SortingDate MO33 = addInstance("1-10-16","DAY","ARASDFR",formatter.parse("2015-06-19"),formatter.parse("2015-06-11"));
    SortingDate MO34 = addInstance("1-10-16","Evening","DEADSEP",formatter.parse("2015-07-01"),formatter.parse("2015-06-11"));
    SortingDate MO41 = addInstance("1-10-16","Night","AGHGFDSR",formatter.parse("2015-06-24"),formatter.parse("2015-06-11"));
    SortingDate MO42 = addInstance("1-10-16","DAY","ARWERR",formatter.parse("2015-06-29"),formatter.parse("2015-06-11"));
    SortingDate MO43 = addInstance("1-10-16","Evening","DDFGP",formatter.parse("2015-06-23"),formatter.parse("2015-06-11"));
    SortingDate MO51 = addInstance("1-10-15","DAY","ARRER",formatter.parse("2015-06-11"),formatter.parse("2015-06-11"));
    SortingDate MO52= addInstance("1-10-15","Evening","ARERR",formatter.parse("2015-06-17"),formatter.parse("2015-06-11"));
    SortingDate MO53 = addInstance("1-10-15","Night","ARRYTR",formatter.parse("2015-06-30"),formatter.parse("2015-06-11"));
    SortingDate MO54 = addInstance("1-10-16","DAY","ARYRRR",formatter.parse("2015-06-26"),formatter.parse("2015-06-11"));
    list.add(MO1);
    list.add(MO21);
    list.add(MO22);
    list.add(MO31);
    list.add(MO32);
    list.add(MO33);
    list.add(MO34);
    list.add(MO41);
    list.add(MO42);
    list.add(MO43);
    list.add(MO51);
    list.add(MO52);
    list.add(MO53);
    list.add(MO54);
    for(SortingDate sortingDate:list){
        Collections.sort(list);
        System.out.println(sortingDate.getStartDateTime().toString());
    }

    }catch(ParseException pe){
        pe.printStackTrace();
    }

}

private static SortingDate addInstance(String mDate,String mType,String mPortion,Date startdatetime,Date enddatetime) throws ParseException{
    DateFormat formatter = new SimpleDateFormat("yyyy-mm-dd");
    SortingDate workUnitBoxInstance = new SortingDate();
    workUnitBoxInstance.setDate(formatter.parse(mDate));
    workUnitBoxInstance.setType("DAY");
    workUnitBoxInstance.setMotion(mPortion);
    workUnitBoxInstance.setStartDateTime(startdatetime);
    workUnitBoxInstance.setEndDateTime(enddatetime);
    return workUnitBoxInstance;

}
}

输出:

Sat Jan 10 00:06:00 IST 2015
Sat Jan 10 00:06:00 IST 2015
Sun Jan 11 00:06:00 IST 2015
Tue Jan 13 00:06:00 IST 2015
Wed Jan 14 00:06:00 IST 2015
Thu Jan 15 00:06:00 IST 2015
Sat Jan 17 00:06:00 IST 2015
Mon Jan 19 00:06:00 IST 2015
Fri Jan 23 00:06:00 IST 2015
Fri Jan 23 00:06:00 IST 2015
Sat Jan 24 00:06:00 IST 2015
Mon Jan 26 00:06:00 IST 2015
Thu Jan 29 00:06:00 IST 2015
Fri Jan 30 00:06:00 IST 2015

Answer 1

尝试提取循环的排序方法!

Collections.sort(list);
for(SortingDate sortingDate:list){
    System.out.println(sortingDate.getStartDateTime().toString());
}

@assylias 的评论是真实的!

mm 表示分钟 MM 表示月份

您应该使用模式“yyyy-MM-dd”作为格式化程序