Java .before()

The Date.before() method checks whether a date occurs before another specified date, and returns a boolean value.

Syntax

firstDate.before(secondDate)

The Date.before() takes only one parameter:

• secondDate: A Date object to be compared chronologically with the first date.

It returns true if the firstDate is before the secondDate and returns false if the firstDate is after the secondDate. However, if a date value is null, it will raise a NullPointerException.

Example

The following example shows the implementation of Date.before():

import java.util.Date;

public class Main {
   public static void main(String[] args) {

      Date firstDate = new Date(2023, 1, 18);
      Date secondDate = new Date(2023, 1, 19);
      Date thirdDate = null;

      System.out.println("Is firstDate before secondDate: " + firstDate.before(secondDate));
      System.out.println("Is secondDate before firstDate: " + secondDate.before(firstDate));
      System.out.println("Is thirdDate before firstDate:" + firstDate.before(thirdDate));
   }
}

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The output will be:

Is firstDate before secondDate: true
Is secondDate before firstDate: false
Exception in thread "main" java.lang.NullPointerException: Cannot invoke "Object.getClass()" because "date" is null
        at java.base/java.util.Date.getMillisOf(Date.java:957)
        at java.base/java.util.Date.before(Date.java:916)
        at Main.main(Main.java:12)

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