Counter variable in Java

A counter variable in Java is a special type of variable which is used in the loop to count the repetitions or to know about in which repetition we are in. In simple words, a counter variable is a variable that keeps track of the number of times a specific piece of code is executed.

The counter variable is declared and used in the same way as the normal variables are declared and used. The counter variable can be of only integer type because it is very easy to increase the value of integer type variable.

The counter variable is very easy to understand and use. The technique of using the counter variable in Java is as follows:

Before the repeating cycle, we have to initialize it to zero or one.
After that, we have to increase the counter variable in one within the respective cycle.

Let's take a simple example to understand the concept of the counter variable in Java.

CounterVariableExample1.java

//create CounterVariableExample1 class to understand the concept of counter
public class CounterVariableExample1{
	//main() method start
	public static void main(String[] args) {
		//initialize counter
		int counter = 0;
		
		//using for loop to increment the counter variable
		for(int i=0; i<5; i++){
			//increment counter variable
			counter = counter + 1;
			//print the incremented counter variable value
			System.out.println(counter);
		}
	}
}

Let's take another example of a counter variable in which we will count the occurrence of the character in the string using counter variable.

CounterVariableExample2.java

//create CounterVariableExample1 to count the occurence of each character in a string using counter variable
class CounterVariableExample2 {
	//set maximum character size
	static final int MAX = 256;
	
    static void getNumberOfSameChar(String str)
    {
        // Create an array of size 256, i.e., ASCII_SIZE
        int count[] = new int[MAX];
		
		//calculate the length of the string 
		int len = str.length(); 
		 
        // Initialize count array index
        for (int i = 0; i < len; i++)
            count[str.charAt(i)]++;
			
		// create a character array of size len
        char charArray[] = new char[len];
 
        // copying each character of string to charArray
        for (int i = 0; i < len; i++){
            charArray[i] = str.charAt(i);
			//initialize counter variable
			int counter = 0;
            
			for (int j = 0; j <= i; j++) {
 
                // increment the counter if any match fount
                if (str.charAt(i) == charArray[j])
                    counter++;
            }
			
			if (counter == 1)
                System.out.println( "The occurrence of character "+str.charAt(i)
                    + " is:" + count[str.charAt(i)]);
        }
    }
   
    // main() method start
    public static void main(String[] args)
    {
		//create variable of string type with default string 
        String str = "javaTpoint is the best learning website";
		
		//call getNumberOfSameChar() method to get the occurence of each character in the string
        getNumberOfSameChar(str);
    }
}

Output