Count Number of Words in a String in Java

import java.util.*;

class WordsCount

{

public static void main(String arg[])

{

int word=1;

Scanner in=new Scanner(System.in);

System.out.println(“Enter your sentence:[Try to ignore space at end]”);

String str=in.nextLine();

for(int i=0;i<str.length();++i)

{

if(str.charAt(i)==’ ‘)

word++;

}

System.out.println(“Number of words=”+word);

}

}

Count Number of Words in a String in Java

Counting the number of words in a string is one of the most common Java programming interview questions for beginners. This program helps students understand string handling, loops, arrays, and conditional statements in Java.

In Java, a word is usually separated by spaces. We can count the total number of words in a string using different approaches such as the split() method, loops, or character traversal.

This tutorial explains multiple ways to count the number of words in a string in Java with proper examples and output.

What is a Word Count Program in Java?

A word count program counts how many words are present inside a string.

Example:

Input:

Java is a programming language

Output:

5

The program counts all words separated by spaces.

Method 1: Count Words Using split() Method

The split() method is one of the easiest ways to count words in Java.

Java Program

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

        String str = "Java is a programming language";

        String[] words = str.trim().split("\\s+");

        int count = words.length;

        System.out.println("Total number of words: " + count);
    }
}

Output

Total number of words: 5

Explanation

• trim() removes extra spaces from the beginning and end of the string.
• split(“\s+”) separates words using spaces.
• words.length returns the total number of words.

Method 2: Count Words Using Loop

We can also count words manually using loops and conditions.

Java Program

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

        String str = "Java programming language";

        int count = 1;

        for(int i = 0; i < str.length(); i++) {

            if(str.charAt(i) == ' ') {
                count++;
            }
        }

        System.out.println("Total number of words: " + count);
    }
}

Output

Total number of words: 3

Explanation

• The loop checks every character in the string.
• Whenever a space is found, the word counter increases.
• Total spaces + 1 gives the number of words.

Method 3: Count Words Using User Input

This method allows users to enter their own string.

Java Program

import java.util.Scanner;

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

        Scanner sc = new Scanner(System.in);

        System.out.println("Enter a string:");

        String str = sc.nextLine();

        String[] words = str.trim().split("\\s+");

        System.out.println("Total number of words: " + words.length);
    }
}

Output

Enter a string:
Java is easy to learn

Total number of words: 5

Why Use trim() in Java?

The trim() method removes unnecessary spaces from the beginning and end of the string.

Without trim(), extra spaces may produce incorrect word counts.

Example:

"   Java Programming   "

After using trim():

"Java Programming"

Understanding split(“\s+”)

The expression:

split("\\s+")

means:

• \\s → whitespace character
• + → one or more spaces

This helps handle multiple spaces correctly.

Time Complexity

The time complexity of the word count program is:

O(n)

Where:

• n is the total number of characters in the string.

The program checks each character only once.

Real-World Uses of Word Count Program

Word count programs are used in:

• Text editors
• Search engines
• Content analysis tools
• SEO tools
• Blogging platforms
• Data processing applications

Common Mistakes Made by Beginners

1. Not Using trim()

Extra spaces may increase the word count incorrectly.

2. Using split(” “)

Using a single space may fail when multiple spaces exist.

Correct approach:

split("\\s+")

3. Forgetting Empty String Check

Always validate empty strings in real applications.

Interview Questions Related to Word Count in Java

Interviewers may ask:

• How does split() work in Java?
• What is the difference between split(” “) and split(“\s+”)?
• How do you count words without using split()?
• How do you handle multiple spaces?

FAQ’s

Conclusion

The word count program in Java is an important beginner-level programming example. It helps students understand string handling, loops, arrays, and input processing in Java.

Using split(“\s+”) is the most efficient and beginner-friendly way to count the number of words in a string. Students should also practice loop-based approaches to improve their logic-building skills.