Question

1. Create a new Java project called L2 and a class named L2

2. Create a second class called ArrayExaminer.

3. In the ArrayExaminer class declare the following instance variables:

a. String named textFileName

b. Array of 20 integers named numArray (Only do the 1st half of the declaration here:

int [] numArray; )

c. Integer variable named largest

d. Integer value named largestIndex

4. Add the following methods to this class:

a. A constructor with one String parameter that

i. does the second half of declaring numArray

(numArray = new int [20];).

ii. Sets textFileName equal to the parameter

iii. Sets the other instance variables to 0.

b. A void method named fillArray that will read 20 integers from a text file (textFileName) and fill the array with the values.

It should also print the array all on one line. (Hint – use the Arrays.toString)

c. void method named findLargest (no parameters) that reads through numArray and sets the instance variable, largest, equal to the largest item in the array, and sets largestIndex equal to its index

Print the value of largest (with a label).

d. boolean method named goingUp (no parameters) that

i. returns a true if all the values in numArray from the beginning up to the largestIndex position are increasing, and false otherwise. (Example of increasing [1,2,6,9,23] )

e. boolean method named goingDown (no parameters) that

i. returns a true if all the values in numArray from largestIndex position until the end are decreasing, and false otherwise. (Example of decreasing [31,12,6,2,1])

f. void method named isPeak (no parameters) that

i. calls findLargest

ii. if goingUp and goingDown are both true, then print that the array has a peak. Otherwise print that it does not have a peak.

5. Back in the main method/class.

a. Declare and instantiate an ArrayExaminer object named array1 and send “L2-1.txt”) as the parameter to its constructor.

b. Call fillArray for array1

c. Call isPeak for array1

d. Declare and instantiate an ArrayExaminer object named array2 and send “L2-2.txt”) as the parameter to its constructor.

e. Call fillArray for array2

f. Call isPeak for array2

L2-1.txt

2

10

17

23

29

38

50

51

62

63

81

85

97

86

75

76

61

59

42

0

L2-2.txt

2

10

17

23

29

38

50

51

62

63

81

85

97

86

75

70

61

59

42

0

Answer 1

Implementation in JAVA:

Code:

// import some neccesary files
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Arrays;
import java.util.Scanner;

// class named L2
public class L2 {

//   main method or driver method
   public static void main(String[] args) throws FileNotFoundException {
      
       System.out.println("\n Outputs for File 1 : ");
      
//       path of file L2-1
       String L21="C:\\Users\\Ankit\\Desktop\\L2-1.txt";
      
//       create object of ArrayExaminer class and pass path string into constructor
       ArrayExaminer ae = new ArrayExaminer(L21);
      
//       call the functions
      
       ae.fillArray();
      
       ae.findLargest();
      
       System.out.println("Array is going up : "+ae.goingup());
      
       System.out.println("Array is going down : "+ae.goingdown());
      
       ae.isPeak();
      
      
//       same done for file 2
System.out.println("\n\n Outputs for File 2 : ");
      
       String L22="C:\\Users\\Ankit\\Desktop\\L2-2.txt";
      
       ArrayExaminer ae1 = new ArrayExaminer(L22);
      
       ae1.fillArray();
      
       ae1.findLargest();
      
       System.out.println("Array is going up : "+ae1.goingup());
      
       System.out.println("Array is going down : "+ae1.goingdown());
      
       ae1.isPeak();

   }

}

// class named ArrayExaminer
class ArrayExaminer{
  
//   instance Variables
  
   String textFilename;
  
   int arr[];
  
   int largest;
  
   int largestindex;
  
//   constructor
   public ArrayExaminer(String textFilename ) {
      
       this.textFilename=textFilename;
      
       arr = new int[20];
      
       largest=0;
      
       largestindex=0;
      
   }
  
//   read file and fill into array
   public void fillArray() throws FileNotFoundException {
      
//       create object of File class and pass path of file
       File file = new File(textFilename);
      
//       Scanner object
       Scanner s = new Scanner(file);
         
       int i=0;
         
//       read file and Store into array
       try
       {
       while( s.hasNext() )
       {
          
           int element = s.nextInt();
          
           arr[i]=element;
          
           i++;
          
       }
       }
       finally
       {
       s.close();
       }
         
//       print Array into one line
       System.out.println("\nArray : "+Arrays.toString(arr));
         
   }
  
//   find largest element and its index
   public void findLargest() {
      
      
       for(int i=0;i<arr.length;i++) {
          
           if(largest<arr[i]) {
              
               largest=arr[i];
              
               largestindex=i;
           }
          
       }
      
       System.out.println("The largest element in Array is : "+largest);
       System.out.println("The largest element index in Array is : "+largestindex);
      
   }
  
//   return is array is going up
   public boolean goingup() {
      
       for(int i=1;i<largestindex;i++) {
          
           if(arr[i-1]>arr[i]) {
               return false;
           }
          
       }
      
       return true;
   }
  
//   return is array is going down
public boolean goingdown() {
      
       for(int i=largestindex+1;i<arr.length;i++) {
          
           if(arr[i-1]<arr[i]) {
               return false;
           }
          
       }
      
       return true;
   }

// print oeak State of Array
public void isPeak() {
     
   if(goingup() && goingdown()) {
         
       System.out.println("Array has a peak.");
         
   }
   else {
     
   System.out.println("Array Does not has a peak.");
   }
}

  
  
}

SAMPLE OUTPUT;

TEXTFILE L2-1;

TEXTFILE L2-2

// PLEASE THUMBS-UP AND RATE POSITIVELY
If you have any doubt regarding this question please ask me in commnets
// THANK YOU:-)