Main.java

/*
 * Example for Arrays
 */

import java.util.Scanner;

class Main
{
    /*
     * This one will have public static void main
     */
    
    public static void main( String[] args)
    {
     
     
        
        /*
         * SET UP
         * We are going to ask the user to input an integer 
         * and we will call it
                              n
         */
        Scanner s = new Scanner(System.in);
        System.out.print(" Please type in an integer :");
        int n = s.nextInt();
        
        /*
         * Task 1.  Create an array of integers from 0 to n-1
         *          call this array ar1.  Print it out below.
         */
        System.out.println("*** PRINTING ar1 *");
         int[] ar1;
        ar1 = new int [n];
        for (int i=0; i<ar1.length; i++)
            ar1[i]=i;
        for (int i=0; i<ar1.length; i++)
        System.out.println("ar1["+i+"] = "+ar1[i] );
                
        /*
         * Task 2.  Create a new array called ar2.
         *          Copy the elements of ar1 into ar2.
         */
        int[] ar2;
        ar2 = new int [n];
        for (int i=0; i<ar2.length; i++)
            ar2[i]=i;
        for (int i=0; i<ar2.length; i++)
        System.out.println("ar2["+i+"] = "+ar2[i] );
        
        /* 
         * Task 3. Add 1 to each element in ar1.  Print it out below
         */
          System.out.println("** Stask 3 **");
        int value;
        for (int i=0 ; i<ar1.length ; i++)
        {
            ar1[i] =  ar1[i] +1;
        }
        for (int i=0 ; i<ar1.length ; i++)
            System.out.println("ar1[" + i + "] = "+ar1[i]);
        

        
        
        /*
         * task 4. Create a new array called ar3.
         *         Copy the elements of ar1 into ar3.  Then do it again
         *         For example
         *         ar1: 1 2 3
         *         ar3: 1 2 3 0 1 2 3
         */
                System.out.println("** test 4 **");
        int[] ar3 = new int[ ar1.length *2 ];
        for (int i=0 ; i< ar1.length ; i++)
        {
            ar3[i]=ar1[i];
        }
        
        for (int i=0 ; i<ar1.length ; i++)
        {
            ar3[i+ar1.length]=ar1[i];
        }
        
        for (int i=0 ; i<ar3.length ; i++)
            System.out.println("ar3[" + i + "] = "+ar3[i]);
        
        /*
         * Task 5.  Switch the first and last element of ar1.
         *          print out the new ar1.  Then switch them back
         */
                System.out.println("** Task 5**");

        // Ye olde switcheroo
      
        value  = ar1[0];  // backup ar1[0] into a bitbucket

        ar1[0] = ar1[ar1.length-1];  // copy last into ar1[0].  

        ar1[ar1.length-1]=value;     // copy old value of ar1[0] into last
        

        // Print out the array
        for (int i=0 ; i<ar1.length ; i++)
            System.out.println("ar1[" + i + "] = "+ar1[i]);
        
        // The Restoration of the rightful heir
        value  = ar1[0];
        ar1[0] = ar1[ar1.length-1];
        ar1[ar1.length-1] = value;
        
        /*
         * Task 6A. Print the 2nd to (n-1)th elements of ar1
         * Task 6B: Print out just the odd numbers in ar1
         * Task 6C: Print out the elements of ar1 when
         *          the indices are multiples of 3
         *         
         */
                System.out.println(" ** Task 6A **");
        
        // print 2nd to (n-1)th element
        for (int i=1 ; i<ar1.length-1 ; i++)
            System.out.println(ar1[i]);
        
            
        System.out.println(" ** Task 6B **");
        // print odd numbers in ar1
        // AKA if ar1[i] is odd, print it out.
        for (int i=0 ; i<ar1.length ; i++)
            if (ar1[i]%2==1)
                System.out.println(ar1[i]);
            
            
        System.out.println(" ** Task 6C **");
        // print elements if it is a multiple of 3
        // AKA if ar1[i] is divisble by 3, print it out.
        // AKA if ar1[2] has a zero as the remainer when divided by 3
        for (int i=0 ; i<ar1.length ; i++)
            if (ar1[i]%3==0)
                System.out.println(ar1[i]);
        
        /*
         * Task 7.  For each element in ar1, 
         *          If the element is even: leave alone
         *          if the element is odd, multiply by 10
         *          print out the new ar1
         *          Example
         *          ar[0]=10
         *          ar[1]=2
         *          ar[2]=30
         *          ar[3]=4
         */
         System.out.println("** Task 7 **");
        
        for (int i=0 ; i<ar1.length ; i++)
        {
            if ( ar1[i]%2==1)
                ar1[i] *=10;
        }
        
        for (int i=0 ; i<ar1.length ; i++)
            System.out.println(ar1[i]);
        
         /*
          * Task 8
          *    Create an array called ar2odds
          *    If the index of ar2 is odd, copy it to ar2odds.
          *    If not, do not
          *    ar2[0]=0
          *    ar2[1]=1  ->  ar2odds[0]=1
          *    ar2[2]=2
          *    ar2[3]=3  ->  ar2odds[1]=3
          */
         System.out.println(" ** Task 8 **");
           int k=0;
           int[] ar2odds = new int[ar2.length]; // too big right now.
           for ( int i=0 ; i<ar2.length ; i++)
           {
               System.out.println(ar2[i]); // Just print it out to see
               
               if (i%2==1)
               {
                   ar2odds[k]=ar2[i];
                   k++;
               }
           }
           
           for (int i=0 ; i<k ; i++)
               System.out.println(ar2odds[i]);
         
        /*
         * Task 9. In the array ar2, count how many odd numbers you
         * have.  Then create an ew array called ar4.  Copy just the odd
         * numbers from ar1 into ar4.  Print ar4
         */
                 int l4=0;
         for (int i=0 ; i<ar2.length ; i++)
         {
             if ( ar2[i]%2==1)
                 l4++;
         } 
         int[] ar4 = new int[l4];
         k=0;
         for (int i=0 ; i<ar2.length ; i++)
         {
             if (ar2[i]%2==1)
             {
                 ar4[k]=ar2[i];
                 k++;
             }
          }
                   
           for (int i=0 ; i<k ; i++)
               System.out.println(ar4[i]);
        
        /*
         * Task 10.  Shift the elements of ar4 right by 1
         * For example
         * old   ar4: 1 3 5 7 9
         * new   ar4  9 1 3 5 7
         */
          System.out.println("** Task 10 ** ");
         System.out.println("Original ar4");
         for (int i=0 ; i<ar4.length ; i++)
             System.out.println(ar4[i]);
        

         int temp10=ar4[ar4.length-1];
         
         for (int i=ar4.length-1 ; i>0 ; i--)
            ar4[i]=ar4[i-1];
         
         ar4[0]=temp10;

         System.out.println("New ar4");
         for (int i=0 ; i<ar4.length ; i++);
             System.out.println(ar4[0]);
        
        
        /*
         * Task 11.  Reverse the order of elements in ar2
         */
                System.out.println("** Task 11 **");
        for (int i=0 ; i<ar2.length ; i++)
            System.out.println("ar2["+i+"] = "+ar2[i]);
            
        int ar2half = ar2.length/2;
        System.out.println(ar2half);
        int task11Temp;
        for (int i=0 ; i<ar2half ; i++)
        {
            task11Temp = ar2[i];
            System.out.println(" "+i+":"+(ar2.length-i));
            ar2[i] = ar2[ar2.length-1-i];
            ar2[ar2.length-1-i]=task11Temp;
        }
               
        for (int i=0 ; i<ar2.length ; i++)
            System.out.println("ar2["+i+"] = "+ar2[i]);
        
        /*
         * Task 12: 
         * Create an array of Strings called ar5.
         * 
         * Each element is a word of the following phrase
         * 
         * 
         * Four score and seven years ago our fathers brought forth on
         * this continent a new nation
         *
         *. ar5[0] = "Four"
         *  ar5[1] = "score"
         *  
         *  Create another array of ints called ar6.  Write a for loop that
         *  will iterate through each element in ar5 and the length of the
         *  word is the element in ar6.
         *  
         *  ar5[0]= "Four"   ar6[0]=4
         *  ar5[1]="score"   ar6[1]=5
         *  ar5[2]="and"     ar6[2]=3
         *  
         *  Count how many words have more than 5 letters.
         */
        
        /*
         * Task 13
         * Create an array called monsterArray of 5 Monsters.
         * The name of the monsters are
         * "Cookie"
         * "Grover"
         * "Oscar the Grouch"
         * "Elmo"
         * "Rosita"
         * 
         * Print out their names
         * Use a for loop to print out the names of monster that start with
         * a vowel
         */
        
         /*
          * Task 14
          * Create an array of integers from 3 to 94 and call it arx
          * Create an array of the indices of arx when the item is
          * divisible by 3.  Call this arindex
          *      arx[0]=94
          *      arx[1]=95
          *      arx[2]=96 // this is divisible.  Index is 2
          *      arx[3]=97
          *      arx[4]=98
          *      arx[5]=99 // this is divisible  Index is 5
          *      
          *      So arindex[0]=2
          *         arindex[1]=5
          */
         
         /*
          * Create an arrary called "fb" and calculate the
          * first 10 fibonacci sequence.  You start with
          * fb[0]=1
          * fb[1]=1
          * fb[2]=fb[0]+fb[1]
          * fb[3]=fb[1]+fb[2]
          * fb[4]=fb[2]+fb[3]
          */
        
    }
}