Question

Write a Java program which takes a string as a user input. Create 2 functions.

The first function expects a string as argument and returns void. It converts all upper case characters to lower case and converts all lower case characters to upper case. It then prints out the converted string to a console.

The second function also expects a string as argument and returns void. It will find first charactor that is repeated exactly 2 times in the string. The function then prints out the character to screen.

Example:

<output>

Enter a string: Hello World <enter icon>

Convert string: hELLO wORLD

The first character that duplicate 2 times is: o

<output>

<output>

Enter a string: Welcome to JaVa Class <enter icon>

Convert string: wELCOME TO jAvA cLASS

The first character that duplicate 2 times is: e

<output>

Answer 1

import java.util.Scanner;

public class StringHelp {

    public static void convertString(String s) {
        System.out.print("Convert string: ");
        for(int i = 0; i < s.length(); ++i) {
            if(Character.isUpperCase(s.charAt(i))) {
                System.out.print(Character.toLowerCase(s.charAt(i)));
            } else if(Character.isLowerCase(s.charAt(i))) {
                System.out.print(Character.toUpperCase(s.charAt(i)));
            } else {
                System.out.print(s.charAt(i));
            }
        }
        System.out.println();
    }

    public static void duplicate(String s) {
        int count;
        for(int i = 0; i < s.length(); ++i) {
            count = 0;
            for (int j = 0; j < s.length(); ++j) {
                if(s.charAt(i) == s.charAt(j)) ++count;
            }
            if(count == 2) {
                System.out.println("The first character that duplicate 2 times is: " + s.charAt(i));
                break;
            }
        }
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a string: ");
        String str = in.nextLine();
        convertString(str);
        duplicate(str);
    }

}

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