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Java Method Exercises: Count all words in a string

Java Method: Exercise-5 with Solution

Write a Java method to count all words in a string.

Test Data:
Input the string: The quick brown fox jumps over the lazy dog.

Pictorial Presentation:

Java Method Exercises: Count all vowels in a string

Sample Solution:

Java Code:

import java.util.Scanner;
public class Exercise5 {

  public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
        System.out.print("Input the string: ");
        String str = in.nextLine();

        System.out.print("Number of words in the string: " + count_Words(str)+"\n");
    }

 public static int count_Words(String str)
    {
       int count = 0;
        if (!(" ".equals(str.substring(0, 1))) || !(" ".equals(str.substring(str.length() - 1))))
        {
            for (int i = 0; i < str.length(); i++)
            {
                if (str.charAt(i) == ' ')
                {
                    count++;
                }
            }
            count = count + 1; 
        }
        return count; // returns 0 if string starts or ends with space " ".
    }
 }

Sample Output:

Input the string: The quick brown fox jumps over the lazy dog                                                  
Number of words in the string: 9 

Flowchart:

Flowchart: Count all words in a string

Java Code Editor:

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Java: Tips of the Day

Array vs ArrayLists:

The main difference between these two is that an Array is of fixed size so once you have created an Array you cannot change it but the ArrayList is not of fixed size. You can create instances of ArrayLists without specifying its size. So if you create such instances of an ArrayList without specifying its size Java will create an instance of an ArrayList of default size.

Once an ArrayList is full it re-sizes itself. In fact, an ArrayList is internally supported by an array. So when an ArrayList is resized it will slow down its performance a bit as the contents of the old Array must be copied to a new Array.

At the same time, it's compulsory to specify the size of an Array directly or indirectly while creating it. And also Arrays can store both primitives and objects while ArrayLists only can store objects.

Ref: https://bit.ly/3o8L2KH