String is a sequence of characters that are immutable, meaning they cannot be changed once they have been created. These strings are used for a variety of purposes including authentication, sorting, and reference matching. The primary operation to compare two strings is based on their values. There are various methods in java to compare two strings, such as equals() and compareTo() method.
The main difference between these two is that equals() checks the value equality while compareTo() checks on the reference equality. The equals() is a static method inherited from Object and it compares the two String objects by comparing their address. Therefore, it will return true if the two string variables refer to the same java object in memory.
However, the problem with this is that it is not accurate because a string variable could be referring to an object of different type. For example, if the first string is stored in a double-quoted variable and the second string is stored as an object defined using new operator, they will have different addresses.
This is the reason why most beginner Java programmers make mistakes when they try to compare two String using == operator. They think that the string value is equal to the other, but they forget that the operator checks only references not their content.
Therefore, it is better to use the equals() method which is a static method inherited from String class. This method compares the string value character by character and if the strings are the same it will return true. This method also takes the case of the string into consideration so if you compare “SONY” and “Samsung” it will return true because both string are the same in terms of their content.
On the other hand, the compareTo() method of String class is a static method which compares the two string lexicographically. This is also called the natural order of the String. It will return 0 if both the String are equal, less than zero if the calling string comes before the argument string and greater than zero if the calling string comes after the argument string.
Another option is to use the compareIgnoreCase() method of String class which compares the String ignoring its case. This is a very useful method to use when you want to compare String that are not the same in terms of their case. The most important thing to remember is that you must always use the right method based on your requirements and not rely on the == or equalsIgnoreCase operator to compare string. This will help you to avoid any bugs in the code and make your coding more efficient.