How to Split a String with a Dot in Java

Programming fundamentals include string manipulation, and Java provides robust tools to handle these kinds of tasks. Splitting a string with a dot or other delimiter is a typical operation. 

We'll cover various methods for splitting a string in Java using a dot in this post. To make sure that you fully comprehend the subject, we'll go through a variety of techniques, code examples, and frequently asked questions.

Split String by Dot in Java using Regular Expression

Let's first understand the problem at issue before delving into the details of string splitting. Consider a scenario where you need to separate numerous segments (dots or periods) from a string into their respective parts. 

For example, have a look at the string "example.first.second.third." We want to effectively divide this string into "example," "first," "second," and "third."

Understand the String.split() Method:

Split(), a method from the String class that Java offers, is practical. It enables you to divide a string into a collection of substrings using a character delimiter or a regular expression.

Leveraging the Power of Regular Expressions

Regex is a common acronym for regular expressions, which offer a flexible way to interact with text patterns. Regex can be an essential tool in the context of string splitting.  Here's how regular expressions can help you accomplish our objective:

import java.util.regex.Pattern;

public class StringSplitter 
{
    public static void main(String[] args) 
	{
        String input = "example.first.second.third.";
        String[] segments = input.split("\\.");
        
        for (String segment : segments) 
		{
            System.out.println(segment);
        }
    }
}

The Pattern class is imported in the code snippet above, and the input string is divided into segments using the split function, which uses a dot as a separator. The dot is a special character in regex, so a double backslash is required before it.

Output:

example
first
second
third

The Regex Breakdown

Let's analyze the regex employed in the code mentioned above to gain a better understanding:

"\\.":  This expression breaks down into two parts – the double backslash \ escapes the special meaning of the dot, and the dot itself. matches any character. Thus, the combination \\. specifically matches the dot character.

Advantages of Regular Expression String Splitting

There are various benefits to string splitting with regular expressions:

Flexibility: Regular expressions are very adaptable since they can handle a broad variety of patterns.

Efficiency: By effectively handling splitting based on complex patterns, the split method minimizes the requirement for manual iteration.

Code Elegance:  Regex-based splitting produces clear, legible code that makes your projects easier to maintain.

Using StringTokenizer:

Using the StringTokenizer class is another approach to divide a string with a dot. Despite being less popular than the split() function, this class offers a simple mechanism for tokenizing strings.

import java.util.StringTokenizer;

public class StringTokenizerExample 
{
    public static void main(String[] args) 
	{
        String input = "java.code";
        StringTokenizer tokenizer = new StringTokenizer(input, ".");
        
        while (tokenizer.hasMoreTokens()) 
		{
            System.out.println(tokenizer.nextToken());
        }
    }
}

Output:

java
code

Using Apache Commons Lang:

For string manipulation, the Apache Commons Lang library provides an effective utility class. The StringUtils class allows you to split a string using a dot.

package com.onlyxcodes;

import org.apache.commons.lang3.StringUtils;

public class ApacheCommonsExample 
{
	public static void main(String args[]) 
	{
        String str = "This is a string with spaces";
		
        String[] words = StringUtils.split(str);

        for (String word : words) 
		{
            System.out.println(word);
        }
    }

}

The StringUtils class from the Apache Commons Lang library is first imported into the Java program in the example above.

Then, a main() method is defined, which accepts an array of strings as input.

The program initially creates the string variable "str" and gives it the value "This is a string with spaces" in the main() method.

The "str" variable is then divided into an array of strings by calling the split() function on the StringUtils class.

The split() method takes two arguments: split string is the first argument, and the delimiter is the second.

The delimiter in this situation is the space character. The array of strings that the split() method returns is kept in the words variable.

The program then publishes each word to the terminal after iterating through the words array.

Output:

This
is
a
string
with
spaces

Using the [ . ] Regular Expression:

In Java, you can use the split() method from the String class with the regular expression as an argument to split a string using the regular expression [ . ]. 

However, the regular expression [ . ] matches any character inside the brackets, which in this case are spaces and dots, not the dot (period) character. 

You must escape the dot with two backslashes (\\.) if you want to split the string using a dot (period) as the delimiter.

Here is an illustration of how to divide a string using a regular expression.

public class Example 
{
    public static void main(String[] args) 
	{
        String input = "This.is.a.sample.string";
		
        String[] parts = input.split("\\."); // Escape the dot with two backslashes

        for (String part : parts) 
		{
            System.out.println(part);
        }
    }
}

The strings "This", "is", "a", "sample", and "string" will be separated from the string "This.is.a.sample.string" to form an array of strings in this example. Input will result in:

Output:

This
is
a
sample
string

How to split string by dot and get the Last Element in Java

Java allows you to delimit a string by a dot and then get the last element of the array that results. 

Here is how to go about it:

This example uses the split() method with the dot as the delimiter to split the input string "example.string.to.split" into an array of strings. 

Examples of components in the generated array are "example," "string," "to," and "split." Parts[parts.length - 1] can be used to retrieve the last element, which in this case would be "split".

public class Example
{
    public static void main(String[] args) 
	{
        String input = "example.string.to.split";
        
        // Split the input string by dot
        String[] parts = input.split("\\.");
        
        // Get the last element from the array
        String lastElement = parts[parts.length - 1];
        
        System.out.println("Last element: " + lastElement);
    }
}

Output:

Last element: split

Since the dot needs to be escaped in regular expressions since it is a special character, double backslashes (\\.) should be used as the argument to the split() method.

How to split string by dot and get the First Element in Java

You can use the split() method of the String class in Java to divide a string by a dot and then extract the first element from the array that results. 

Here's an illustration:

The split(".") method call in this illustration divides the input string "usa.uk.australia" into an array of strings: "usa", "uk", and "australia". Then, to get an "usa," you access the array's first entry (index 0).

public class Example
{
    public static void main(String[] args) 
	{
        String input = "usa.uk.australia";
		
        String[] parts = input.split("\\."); // Use double backslash to escape the dot
		
        String firstElement = parts[0];
		
        System.out.println("First element: " + firstElement);
    }
}

Output:

First element: usa

How do you split a second dot in Java

Java may be used to divide a second dot in a string as follows:

Identify the String: You must have the input string with the dots in it first.

Find the First Dot: To determine the index of the first dot in the string, use the indexOf() method. You can use this to find the first dot's location.

Find the Second Dot:  You can now look for the string's second dot. Use indexOf() once more to accomplish this, but this time, place the starting index one position after the index of the first dot.

Extract Substring:  The substring() method can be used to extract the section of the string between the first and second dots after you know the indices of the first and second dots.

Here's some sample code illustrating these steps:

public class SplitSecondDotExample 
{
    public static void main(String[] args) 
	{
        String input = "example.first.second.dot";
        
        int firstDotIndex = input.indexOf(".");
		
        if (firstDotIndex != -1) // Check if the first dot is found
		{ 
            int secondDotIndex = input.indexOf(".", firstDotIndex + 1);
            
            if (secondDotIndex != -1) // Check if the second dot is found
			{ 
                String result = input.substring(firstDotIndex + 1, secondDotIndex);
				
                System.out.println("Substring between the second dots: " + result);	
            } 
			else 
			{
                System.out.println("Second dot not found in the string.");
            }
        } 
		else 
		{
            System.out.println("First dot not found in the string.");
        }
    }
}

Don't forget to swap out "example.first.second.dot" for your actual input string. The substring between the first and second dots in the input string will be output by this code.

Output:

Substring between the second dots: first

How to split a string with a special character in Java

Java's split method, which is part of the String class, can be used to divide a string containing a special character. 

The split method partitions the string according to the regular expression pattern given as an input. A string can be split using a special character as seen in the following example:

The pipe symbol ( | ) is used as a delimiter to divide the input string "Hello|World|Java|Genius" in this example. 

We must escape the pipe symbol using a double backslash (\\|), as it is a special character in regular expressions.

public class Example 
{
    public static void main(String[] args) 
	{
        String input = "Hello|World|Java|Genius";
		
        String delimiter = "\\|"; // Using escape character for the pipe symbol

        String[] parts = input.split(delimiter);

        for (String part : parts) 
		{
            System.out.println(part);
        }
    }
}

When you run this code, it will output:

Output:

Hello
World
Java
Genius

The special character you want to use as the delimiter in your particular circumstance can be substituted for "|". If the special character is also a special character in regular expressions, just remember to escape it correctly.

How to split a string by comma in Java

In this case, the input string with the comma as the delimiter is passed to the split() method. The output of this method is an array of comma-separated substrings. The array can then be iterated through, with each element being processed as necessary.

public class Example 
{
    public static void main(String[] args) 
	{
        String input = "apple,banana,orange,grape";
        
        String[] splitArray = input.split(",");
        
        for (String item : splitArray) 
		{
            System.out.println(item);
        }
    }
}

Output:

apple
banana
orange
grape