Counting Spaces in a Java String

How to Count Spaces in a Java String

When working with strings in Java, it can be useful to know how many spaces are contained in the string. Knowing this information is helpful when designing algorithms or validating input, for example. Luckily, counting the number of spaces in a Java string is easy and requires just a few lines of code. Let's take a closer look!

Using the Java length() method

The most straightforward way to count the number of spaces in a Java string is by using the length() method. The length() method returns the total character count of a string, where a 'space' character is considered one of the characters.

String myStr = "Hello World!";
int spaceCount = 0;
 
for (int i = 0; i < myStr.length(); i++) {
  if (myStr.charAt(i) == ' ') {
    spaceCount++;
  }
}
 
System.out.println("Space count = " + spaceCount);

In the example above, we initialize a variable called spaceCount, which will store the number of spaces. We then set up a loop that iterates through each character of the string, checking if that character is a space. If it is, we increment our spaceCount variable by one. At the end, we print out the final value of spaceCount.

Using the Java replaceAll() method

Another approach is to use the replaceAll() method. The replaceAll() method takes a regular expression as an argument and replaces all occurrences of that expression with a provided replacement string. In the example below, we use the replaceAll() method to replace all spaces with an empty string, and then compare the length of the original string to the length of the modified string.

String myStr = "Hello World!";
int spaceCount = 0;
 
String modifiedStr = myStr.replaceAll(" ", "");
spaceCount = myStr.length() - modifiedStr.length();
 
System.out.println("Space count = " + spaceCount);

By subtracting the length of the modified string (with all the spaces removed) from the length of the original string, we can get the total number of spaces. In this example, the answer will be 1, since there is only one space character in the example string.

Conclusion

Counting the number of spaces in a Java string is easy. The simplest approach is to use the length() method, but if you need a more robust solution, the replaceAll() method is also available. With these techniques, you'll be able to count the number of spaces in any Java string quickly and easily.