What are the different character extraction methods? Explain with a program.

5.B] What are the different character extraction methods? Explain with a program.

Answer:

Java provides several methods to extract characters or sequences of characters from a String object. These methods are useful for retrieving specific characters, substrings, or sequences from strings.

1. charAt(int index)

• Extracts a single character at a specified index.
• Syntax: char ch = str.charAt(index);
• Example:

  String str = "Hello";
  char ch = str.charAt(1);
  System.out.println("Character at index 1: " + ch); // Output: e

2. getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)

• Extracts a sequence of characters from a string and stores them in a character array.
• Syntax: str.getChars(srcBegin, srcEnd, dst, dstBegin);
• Example:

  String str = "Hello";
  char[] dst = new char[3];
  str.getChars(1, 4, dst, 0);
  System.out.println("Extracted characters: " + new String(dst)); // Output: ell

3. toCharArray()

• Converts the entire string into a character array.
• Syntax: char[] charArray = str.toCharArray();
• Example:

  String str = "Hello";
  char[] charArray = str.toCharArray();
  System.out.println("Character array: " + Arrays.toString(charArray)); // Output: [H, e, l, l, o]

4. substring(int beginIndex)

• Extracts a substring from the specified begin index to the end of the string.
• Syntax: String subStr = str.substring(beginIndex);
• Example:

  String str = "Hello";
  String subStr = str.substring(2);
  System.out.println("Substring from index 2: " + subStr); // Output: llo

5. substring(int beginIndex, int endIndex)

• Extracts a substring from the specified begin index to the specified end index.
• Syntax: String subStr = str.substring(beginIndex, endIndex);
• Example:

  String str = "Hello";
  String subStr = str.substring(1, 4);
  System.out.println("Substring from index 1 to 4: " + subStr); // Output: ell

Program Example:-

Here’s a simple program that demonstrates the use of different character extraction methods:

public class CharacterExtractionExample {
    public static void main(String[] args) {
        String str = "Hello";

        // 1. Using charAt()
        char ch = str.charAt(1);
        System.out.println("Character at index 1: " + ch); // Output: e

        // 2. Using getChars()
        char[] dst = new char[3];
        str.getChars(1, 4, dst, 0);
        System.out.println("Extracted characters using getChars: " + new String(dst)); // Output: ell

        // 3. Using toCharArray()
        char[] charArray = str.toCharArray();
        System.out.println("Character array using toCharArray: " + Arrays.toString(charArray)); // Output: [H, e, l, l, o]

        // 4. Using substring(beginIndex)
        String subStr1 = str.substring(2);
        System.out.println("Substring from index 2: " + subStr1); // Output: llo

        // 5. Using substring(beginIndex, endIndex)
        String subStr2 = str.substring(1, 4);
        System.out.println("Substring from index 1 to 4: " + subStr2); // Output: ell
    }
}

Summary:-

• charAt(int index): Extracts a single character at the specified index.
• getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin): Extracts a sequence of characters into a character array.
• toCharArray(): Converts the entire string into a character array.
• substring(int beginIndex): Extracts a substring from the specified index to the end of the string.
• substring(int beginIndex, int endIndex): Extracts a substring from the specified begin index to the specified end index.