๐Ÿ“ Strings in Java

In Java, a String is a sequence of characters. It is a widely used class for manipulating text. Strings are immutable, meaning once a string is created, its value cannot be changed.

๐Ÿง  String Characteristics

  1. Immutable

    • Once a string object is created, its value cannot be modified. Any operation on a string creates a new string object.

  2. String Pool

    • Java maintains a pool of strings to optimize memory usage. If the same string is created multiple times, the JVM reuses the string from the pool instead of creating a new one.

  3. String Length

    • The length of a string can be obtained using the .length() method.

๐Ÿ”น Creating Strings in Java

  1. Using String Literals

    • When you use a string literal, Java automatically adds it to the string pool.
    String str = "Hello, Java!";


2. **Using the `new` Keyword**

   * You can create a string explicitly using the `new` keyword, which will create a new object in memory.

   ```java
   String str2 = new String("Hello, Java!");

๐Ÿงช Example: String Methods

public class StringsExample {
    public static void main(String[] args) {
        String str1 = "Hello";
        String str2 = "World";
        
        // Concatenation
        String result = str1 + " " + str2;
        System.out.println("Concatenation: " + result);

        // Length
        System.out.println("Length of str1: " + str1.length());

        // Convert to Uppercase
        System.out.println("Uppercase: " + str1.toUpperCase());

        // Check if the string contains a substring
        System.out.println("Contains 'Java': " + result.contains("Java"));
    }
}

๐Ÿ”ง Common String Methods

  1. .length() - Returns the length of the string.
  2. .toUpperCase() - Converts the string to uppercase.
  3. .toLowerCase() - Converts the string to lowercase.
  4. .substring() - Extracts a portion of the string.
  5. .equals() - Compares two strings for equality.
  6. .charAt() - Returns the character at a specified index.

๐Ÿ”— Related Notes