How to count a string in java w3schools

Carry 23 Published: 09/17/2024

How to count a string in java w3schools

I'm happy to help you with that! Here's how to count the number of strings in Java according to W3Schools:

Counting Strings

To count the number of strings, you can use the length property or the size() method (in case you're using a collection). Here's an example:

String[] myStrings = {"Hello", "World", "Java"};
// Using length property
int count = myStrings.length;
// Printing the result
System.out.println("Number of strings: " + count);
// Using size() method (for collections)
List myArrayList = new ArrayList(Arrays.asList(myStrings));
int count2 = myArrayList.size();
// Printing the result
System.out.println("Number of strings: " + count2);

In this example, we create a string array myStrings and then use the length property or size() method to get the number of elements in it. We can also use an ArrayList instead of an array for the same purpose.

Using Scanner Class

If you're reading input from the console (user), you can use the Scanner class to count the number of strings:

import java.util.Scanner;
public class StringCount {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("Enter a string (type 'stop' to finish):");
int count = 0;
while (true) {
String str = scanner.nextLine();
if (str.equalsIgnoreCase("stop")) {
break;
}
count++;
}
// Printing the result
System.out.println("Number of strings: " + count);
}
}

In this example, we use a Scanner to read input from the console. We keep reading until the user types 'stop', and then we print the number of strings entered.

These are just some examples on how you can count the number of strings in Java according to W3Schools. I hope that helps!

How to count a string in java for loop

I'm happy to help you with that!

In Java, counting the number of occurrences of a substring within another string can be achieved using various methods. One common approach is by employing a for loop. Here's how you can do it:

public class Main {
public static void main(String[] args) {
String str = "Hello, world! This is a test";
String subStr = "o"; // substring to be searched
int count = 0;
for (int i = 0; i < str.length(); i++) {
if (str.substring(i).startsWith(subStr)) {
while (i + subStr.length() <= str.length()
&& str.startsWith(subStr, i)) {
i += subStr.length();
}
count++;
} else {
i--;
}
}
System.out.println("Number of occurrences: " + count);
}
}

In this code:

We start by defining a string str and the substring we want to search for, subStr. Initialize an integer variable count to keep track of the occurrences. Then we iterate over each character in str using a for loop. Within the loop, use substring(i) to get the remaining part of str starting from index i. Check if it starts with subStr using startsWith() method. If it is found, increment count and keep track of where in the string we found the last occurrence so that we can skip over subsequent occurrences. Use while loop to make sure we find all occurrences of subStr, not just the first one. Finally, print out the count.

In this code, we use the substring(i) and startsWith(subStr, i) method combination to check if a substring starts with our target subStr. This is because Java's string methods are optimized for small strings, so using substring(i) helps in terms of performance. The while loop within the if statement ensures that we find all occurrences of subStr, not just the first one.

If you want to count overlapping occurrences of the substring (like "oo" in "Hello, world"), you can use this modified code:

public class Main {
public static void main(String[] args) {
String str = "Hello, world! This is a test";
String subStr = "o"; // substring to be searched
int count = 0;
for (int i = 0; i < str.length(); i++) {
if (str.indexOf(subStr) != -1) { // Check if subStr is found
count++;
i += subStr.length() - 1; // Skip over the current occurrence
}
}
System.out.println("Number of occurrences: " + count);
}
}

In this modified code:

Use indexOf(subStr) to check if subStr is found at all in str. If not, it returns -1. If it's found, increment the count. And finally, use i += subStr.length() - 1; to skip over the current occurrence.

Now we are able to count the number of occurrences of a substring within another string using for loop in Java.

Let me know if you need any further assistance!