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public class UserString {
        private String str;

            public UserString(String str) {
                        this.str = str;
            }

                // a) Count all the characters
                    public int countCharacters() {
                                return str.length();
                    }

                        // b) Count no of words
                            public int countWords() {
                                        if (str == null || str.isEmpty()) {
                                                        return 0;
                                        }
                                                String[] words = str.split("\\s+"); // Split by one or more spaces
                                                        return words.length;
                            }

                                // c) Compare two strings
                                    public boolean compareStrings(UserString other) {
                                                return str.equals(other.str);
                                    }

                                        // d) Convert to uppercase
                                            public String toUppercase() {
                                                        return str.toUpperCase();
                                            }

                                                // e) Convert to lowercase
                                                    public String toLowercase() {
                                                                return str.toLowerCase();
                                                    }

                                                        // f) Concatenate two strings
                                                            public String concatenate(UserString other) {
                                                                        return str.concat(other.str);
                                                            }

                                                                // g) Check a string is palindrome or not
                                                                    public boolean isPalindrome() {
                                                                                String reversed = new StringBuilder(str).reverse().toString();
                                                                                        return str.equals(reversed);
                                                                    }

                                                                        // h) Find the position of a given character
                                                                            public int findPosition(char ch) {
                                                                                        return str.indexOf(ch);
                                                                            }

                                                                                // i) Make a substring from a desired start and end position.
                                                                                    public String makeSubstring(int start, int end) {
                                                                                                return str.substring(start, end);
                                                                                    }

                                                                                        // j) Search the presence of a substring.
                                                                                            public boolean searchSubstring(String sub) {
                                                                                                        return str.contains(sub);
                                                                                            }

                                                                                                // k) Replace a substring with a new string.
                                                                                                    public String replaceSubstring(String oldSub, String newSub) {
                                                                                                                return str.replace(oldSub, newSub);
                                                                                                    }

                                                                                                        // l) Swap two substrings between two strings.
                                                                                                            public static String swapSubstrings(String str1, String sub1, String str2, String sub2) {
                                                                                                                        String temp = str1.replace(sub1, sub2);
                                                                                                                                return str2.replace(sub2, sub1);
                                                                                                            }

                                                                                                                public static void main(String[] args) {
                                                                                                                            UserString str1 = new UserString("Hello World");
                                                                                                                                    UserString str2 = new UserString("hello world");

                                                                                                                                            System.out.println("String 1: " + str1.str);
                                                                                                                                                    System.out.println("String 2: " + str2.str);
                                                                                                                                                            System.out.println("Character count: " + str1.countCharacters());
                                                                                                                                                                    System.out.println("Word count: " + str1.countWords());
                                                                                                                                                                            System.out.println("Compare strings: " + str1.compareStrings(str2));
                                                                                                                                                                                    System.out.println("Uppercase: " + str1.toUppercase());
                                                                                                                                                                                            System.out.println("Lowercase: " + str1.toLowercase());
                                                                                                                                                                                                    System.out.println("Concatenated: " + str1.concatenate(str2));
                                                                                                                                                                                                            System.out.println("Is palindrome: " + str1.isPalindrome());
                                                                                                                                                                                                                    System.out.println("Position of 'o': " + str1.findPosition('o'));
                                                                                                                                                                                                                            System.out.println("Substring (0, 5): " + str1.makeSubstring(0, 5));
                                                                                                                                                                                                                                    System.out.println("Contains 'World': " + str1.searchSubstring("World"));
                                                                                                                                                                                                                                            System.out.println("Replace 'World' with 'Java': " + str1.replaceSubstring("World", "Java"));

                                                                                                                                                                                                                                                    String string1 = "This is string one";
                                                                                                                                                                                                                                                            String string2 = "This is string two";
                                                                                                                                                                                                                                                                    String swapped = swapSubstrings(string1, "one", string2, "two");
                                                                                                                                                                                                                                                                            System.out.println("Swapped strings: " + swapped);
                                                                                                                }
}

                                                                                                                }
                                                                                                            }
                                                                                                    }
                                                                                            }
                                                                                    }
                                                                            }
                                                                    }
                                                            }
                                                    }
                                            }
                                    }
                                        }
                            }
                    }
            }
}