Tag: compare

Categories
java String

How to compare two strings in java

while loop in java

In this post, We will learn How to compare two strings in java

It might sounds easy. But we need to take care of few things while comparing two Strings

Avoid ==

If you are newbie to java, This might surprise you

while you use == to compare string it will not check the value of two strings

Instead of that it will check the reference of two Strings

"BeginnersBug" == new String("BeginnersBug") 
// Above check will return false

In the above snippet even though both the String are equal it will return false because both are not same object

.equals() method

.equlas method will compare two strings with the value irrespective of its object

Even though if it is two different object it will compare the value of two string

"BeginnersBug".equals(new String("BeginnersBug")) 
// Above check will return true

In the above code snippet it will compare two string value and it will return true for the condition

. equalsIgnoreCase() method

equalsIgnoreCase() method will ignore the case while checking the value of two Strings

If you want to check two Strings irrespective of case sensitive you can use this method

"beginnersbug".equalsIgnoreCase(new String("BeginnersBug")) 
// Above method will return true

In the above code snippet equalsIgnoreCase method will ignore the case sensitive. So it is returning true for the statement

Example

public class CompareStringExample {
	public static void main(String[] args) {
		try {
			// Example 1 == Below check will failS
			if ("BeginnersBug" == new String("BeginnersBug")) {
				System.out.println("Example 1 : Both the strings are equal");
			} else {
				System.out.println("Example 1 : Both the strings are not equal");
			}

			// Example 2 .equals()
			if ("BeginnersBug".equals(new String("BeginnersBug"))) {
				System.out.println("Example 2 : Both the strings are equal");
			} else {
				System.out.println("Example 2 : Both the strings are not equal");
			}

			// Example 3 .equalsIgnoreCase()
			if ("beginnersbug".equalsIgnoreCase(new String("BeginnersBug"))) {
				System.out.println("Example 3 : Both the strings are equal");
			} else {
				System.out.println("Example 3 : Both the strings are not equal");
			}

		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}
Output
Example 1 : Both the strings are not equal
Example 2 : Both the strings are equal
Example 3 : Both the strings are equal
Reference

https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#equalsIgnoreCase(java.lang.String)

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Categories
date java

compare two dates in java example

while loop in java

 

In this post, we will learn to compare two dates in java example

There are multiple ways to compare two dates in java.

In the First example we will learn to compare dates using compareTo() method

While using compareTo() method we are having 3 chances of output. Below are the possible output

0 – When both the dates are equal

1 – When date 1 is greater than date 2

-1 – When date 1 is lesser than date 2

Syntax
date1.compareTo(date2)
Example

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

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

			String date1 = "22/02/2020";
			String date2 = "21/02/2020";
			DateFormat format = new SimpleDateFormat("DD/MM/yyyy");
			Date dateObj1 = format.parse(date1);
			Date dateObj2 = format.parse(date2);

			// If Both the date are same comparTo Method will return 0
			if (dateObj1.compareTo(dateObj2) == 0) {
				System.out.println("Both the dates are Equal !!");
			} // If date1 greater than date 2 it will return 1
			else if (dateObj1.compareTo(dateObj2) > 0) {

				System.out.println("Date 1 is greater than date 2");
			} // If date1 lesser than date 2 it will return -1
			else {
				System.out.println("Date 1 is lesser than date 2");
			}

		} catch (Exception e) {
			e.printStackTrace();
		}

	}

}

Date 1 is greater than date 2

Using equals(),after(),before()

In the above example, we learned using compareTo() method. But we can compare dates using predefined functions also.

Below example is another way to compare two dates in java 

equals() – return true if both the dates are equal

after() – return true if date 1 greater than date 2

before() – return true if date 1 lesser than date 2

Example

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

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

			String date1 = "20/02/2020";
			String date2 = "21/02/2020";
			DateFormat format = new SimpleDateFormat("DD/MM/yyyy");
			Date dateObj1 = format.parse(date1);
			Date dateObj2 = format.parse(date2);

			// If Both the date are same comparTo Method will return 0
			if (dateObj1.equals(dateObj2)) {
				System.out.println("Both the dates are Equal !!");
			} // If date1 greater than date 2 it will return 1
			else if (dateObj1.after(dateObj2)) {

				System.out.println("Date 1 is after than date 2");
			} // If date1 lesser than date 2 it will return -1
			else if (dateObj1.before(dateObj2)) {
				System.out.println("Date 1 is before than date 2");
			}

		} catch (Exception e) {
			e.printStackTrace();
		}

	}

}
Output
Date 1 is before than date 2
Reference

https://docs.oracle.com/javase/8/docs/api/java/util/Date.html#compareTo-java.util.Date-

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