/////////////////////////////////////////////
// TASK 1 SOLUTION
/////////////////////////////////////////////

public class Task1 {
    public static void main(String[] args) {
        String s1 = "ABC";
        String s2 = new String("ABC");
        char[] c = {'A','B','C'}; 
        String s3 = new String(c);
    }
}   





/////////////////////////////////////////////
// TASK 2 SOLUTION
/////////////////////////////////////////////

/**********************************
 * Exercise 11: TA Solution 
 * Date: 04/20/2004 
 * 
 * Gabe Heafitz: gjh2, 999999
 **********************************/
 
  /*
   * Task 2: Create a program Task2.java that converts the 
   * array of characters {'h','e','l','l','o'} to
   * to an uppercase String with two techniques:
   * (a) using the String API
   * (b) only using character arithmetic (review MATLAB notes...)
   * Output your results for both approaches.
   */
public class Task2 {
 
  /**
   * Convert a string to all upper case using the String API.
   */
  public String convertMethodA(String input){
   return  input.toUpperCase();
  }
  
  /**
   * Convert a string to all upper case using character arithmetic.
   */
  public String convertMethodB(String input){
    char[] result = new char[input.length()];
    for (int i = 0; i < input.length(); i++){
     result[i] = (char)((int)(input.toCharArray())[i] + ('A' - 'a')); 
    }
    return new String(result);
  }
  
  /**
   * Main method.  We're using this to call our conversion methods.
   */
  public static void main(String[] args){
   String convertMe = "hello"; // This is the string we'll convert.
   
   Task2 whoNeedsStatic = new Task2();
   
   System.out.println("This is the original string to convert: " + convertMe + ".");
   System.out.println("This is the string, converted using method A: " + whoNeedsStatic.convertMethodA(convertMe) + ".");
   System.out.println("This is the string, converted using method B: " + whoNeedsStatic.convertMethodB(convertMe) + ".");
  }
  
}






/////////////////////////////////////////////
// TASK 3 SOLUTION
/////////////////////////////////////////////

public class Task3{
	public static void main(String args[]) {
		String str = randomString(10);
		System.out.println();
		System.out.println("The random string is: " + str);
		int count = countNonAlphabet(str);
		System.out.println("It has " + count + " non-alphabetic characters");
		String newStr = extractAlphabet(str);
		System.out.println("The new string constructed by its alphabetic characters is: " + newStr);
	}
	
	public static String randomString(int len) {
		char s[] = new char[len];
		for (int i = 0; i < len; i++) {
			s[i] = (char)myRandom(0, 127);
		}
		return new String(s);
	}
	
	public static int countNonAlphabet(String str) {
		if (str == null) return 0;
		
		int count = 0;
		for(int i = 0; i < str.length(); i++) {
			if (!Character.isLetter(str.charAt(i)))
				count++;
		}
		return count;
	}
	
	public static String extractAlphabet(String str) {
		if (str == null) return null;
		
		String newStr = "";
		for(int i = 0; i < str.length(); i++) {
			if (Character.isLetter(str.charAt(i)))
				newStr += str.charAt(i);
		}
		return newStr;
	}
	
	public static int myRandom(int low, int high) {
        	return (int) (Math.random()*(high-low+1)) + (int) low;
    	}
}