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[Java] 比较两个日期先后 →→→→→进入此内容的聊天室

来自 , 2019-12-12, 写在 Java, 查看 137 次.
URL http://www.code666.cn/view/883e881b
  1. import java.text.DateFormat;
  2. import java.text.ParseException;
  3. import java.text.SimpleDateFormat;
  4. import java.util.Calendar;
  5. import java.util.Date;
  6.  
  7. public class HashtableDemo {
  8.  
  9.     public static void main(String args[]) throws AssertionError, ParseException {
  10.  
  11.         DateFormat df = new SimpleDateFormat("dd-MM-yyyy");
  12.  
  13.         //comparing date using compareTo method in Java
  14.         System.out.println("Comparing two Date in Java using CompareTo method");
  15.         compareDatesByCompareTo(df, df.parse("01-01-2012"), df.parse("01-01-2012"));
  16.         compareDatesByCompareTo(df, df.parse("02-03-2012"), df.parse("04-05-2012"));
  17.         compareDatesByCompareTo(df, df.parse("02-03-2012"), df.parse("01-02-2012"));
  18.  
  19.         //comparing dates in java using Date.before, Date.after and Date.equals
  20.         System.out.println("Comparing two Date in Java using Date's before, after and equals method");
  21.         compareDatesByDateMethods(df, df.parse("01-01-2012"), df.parse("01-01-2012"));
  22.         compareDatesByDateMethods(df, df.parse("02-03-2012"), df.parse("04-05-2012"));
  23.         compareDatesByDateMethods(df, df.parse("02-03-2012"), df.parse("01-02-2012"));
  24.  
  25.         //comparing dates in java using Calendar.before(), Calendar.after and Calendar.equals()
  26.         System.out.println("Comparing two Date in Java using Calendar's before, after and equals method");
  27.         compareDatesByCalendarMethods(df, df.parse("01-01-2012"), df.parse("01-01-2012"));
  28.         compareDatesByCalendarMethods(df, df.parse("02-03-2012"), df.parse("04-05-2012"));
  29.         compareDatesByCalendarMethods(df, df.parse("02-03-2012"), df.parse("01-02-2012"));
  30.  
  31.     }
  32.  
  33.     public static void compareDatesByCompareTo(DateFormat df, Date oldDate, Date newDate) {
  34.         //how to check if date1 is equal to date2
  35.         if (oldDate.compareTo(newDate) == 0) {
  36.             System.out.println(df.format(oldDate) + " and " + df.format(newDate) + " are equal to each other");
  37.         }
  38.  
  39.         //checking if date1 is less than date 2
  40.         if (oldDate.compareTo(newDate) < 0) {
  41.             System.out.println(df.format(oldDate) + " is less than " + df.format(newDate));
  42.         }
  43.  
  44.         //how to check if date1 is greater than date2 in java
  45.         if (oldDate.compareTo(newDate) > 0) {
  46.             System.out.println(df.format(oldDate) + " is greater than " + df.format(newDate));
  47.         }
  48.     }
  49.  
  50.     public static void compareDatesByDateMethods(DateFormat df, Date oldDate, Date newDate) {
  51.         //how to check if two dates are equals in java
  52.         if (oldDate.equals(newDate)) {
  53.             System.out.println(df.format(oldDate) + " and " + df.format(newDate) + " are equal to each other");
  54.         }
  55.  
  56.         //checking if date1 comes before date2
  57.         if (oldDate.before(newDate)) {
  58.             System.out.println(df.format(oldDate) + " comes before " + df.format(newDate));
  59.         }
  60.  
  61.         //checking if date1 comes after date2
  62.         if (oldDate.after(newDate)) {
  63.             System.out.println(df.format(oldDate) + " comes after " + df.format(newDate));
  64.         }
  65.     }
  66.  
  67.     public static void compareDatesByCalendarMethods(DateFormat df, Date oldDate, Date newDate) {
  68.  
  69.         //creating calendar instances for date comparision
  70.         Calendar oldCal = Calendar.getInstance();
  71.         Calendar newCal = Calendar.getInstance();
  72.  
  73.         oldCal.setTime(oldDate);
  74.         newCal.setTime(newDate);
  75.  
  76.         //how to check if two dates are equals in java using Calendar
  77.         if (oldCal.equals(newCal)) {
  78.             System.out.println(df.format(oldDate) + " and " + df.format(newDate) + " are equal to each other");
  79.         }
  80.  
  81.         //how to check if one date comes before another using Calendar
  82.         if (oldCal.before(newCal)) {
  83.             System.out.println(df.format(oldDate) + " comes before " + df.format(newDate));
  84.         }
  85.  
  86.         //how to check if one date comes after another using Calendar
  87.         if (oldCal.after(newCal)) {
  88.             System.out.println(df.format(oldDate) + " comes after " + df.format(newDate));
  89.         }
  90.     }
  91. }
  92. //源代码片段来自云代码http://yuncode.net
  93.                        

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