Arrays Solutions

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Introduction These are the solutions for the review questions for arrays.
		Overview If you did not answer any of these questions successfully make sure to go back and re-read the material. If you have trouble understanding the material talk to your prof or a TA

Review Questions

Question 1

This is called an out of bounds error

Question 2

This is called a one off error

Question 3

The second statement makes a copy of the address that is stored in array1. Now array2 gets the address.

Question 4

No. Here the == operator compares the memory address of the reference variable not the contents of the objects referenced by the variable.

Question 5

No. The array element array[10] is changed to "Hello", but the contents of i are unchanged.

Question 6

The string "Gello" is printed.

Question 7

The numbers array will be reversed. In the end, numbers = {5,4,3,2,1}.

Exercises

Exercise 1

int product = 1;
int array[] = new int[10];

//have values entered into the array

//calculate the product
for(int i=0; i<array.length; i++)
{
   product *= array[i];
}

Exercise 2

int lowPos;
int lowest = INTEGER.MAX_VALUE;    //set to the highest possible value so everything is smaller
int array[] = new int[100];

//have values entered into the array

//go through the array
for(int i=0; i<array.length; i++) 
{
   if(array[i] < lowest) 
   {
      lowest = array[i];
      lowPos = i;
   }
}

Exercise 3

import java.io.*;

public class CreateArray
{

  public static void main(String []args)
  {  
    //create an array 
    int[] numbers = new int[10];
    //populating array
    for(int i=0;i<10;i++)
    {
       numbers[i]=10+i;
    }

    //displaying array elements
    for(i=0;i<10;i++)
    {
       System.out.println(numbers[i]);
    }
  }
}

Exercise 4

public class ArrayCopy
{
   public static void main(String []args)
   {
       int array1[]={1,2,3,5}
       int array2[]=new int[4];
     
       //This loop copys contents from array1 to array2 
       for(int i=0;i<array1.length();i++)
       {
           array2[i]=array1[i];
       }
   }
}

Exercise 5

public static void sortArray (int[] array) 
{
    int j = 0, k = 0, temp = 0;

    for (j = 0; j < array.length; j++) 
    {
        for (k = 0; k < array.length - 1; k++) 
        {
            if (array[k] > array[k + 1]) 
            {
                temp = array[k];
                array[k] = array[k + 1];
                array[k + 1] = temp;
            }
        }
    }
}

Exercise 6

void printArray (Object[] array) 
{
    int j = 0;

    for (j = 0; j < array.length; j++) 
    {
        System.out.println(array[j].toString);
    }
}

Exercise 7

Here is a sample program for Exercise 7.

import java.util.*;


public class RandomNumber{
	public static void main(String [] args){

	//Variable Declarations
	int[] randomNumbers = new int[100];
	int[] frequencyArray = new int[12];
	int counter=0;
	int count=1;
	final int LOW = 1;  //the
	final int HIGH = 12;



	//Processing
	for(counter = 0; counter<randomNumbers.length;counter++){
		randomNumbers[counter] = (int)(Math.random()*HIGH) + LOW; //Generates random Numbers between 1 and 12
	 }
    for(counter = 0; counter<randomNumbers.length;counter++){
		frequencyArray[  randomNumbers[counter]-1  ]++;
	 }

	//Output
	for(counter = 0;counter<frequencyArray.length;counter++){
		System.out.println("There are "+frequencyArray[counter]+" number of "+count+"'s");
		count++;
     }

     System.out.println("\nEnd Of Processing");


  }
}