Question

CSC1465L: Operating Systems Lab Consider the threads hierarchy below: T2 T1 T3 T1 will ask the user to enter an array of size N and will fill the array with student grades. T1 will then send the array to threads T2 and T3. T2 will compute the maximum grade of passed students. T3 will compute the maximum grade of failed students. T1 will print the maximum and minimum grades returned by threads T2 and 13. Note: A student passes an exam if his/her grade is greater than or equal to 60. T1 is the main thread.

Answer 1

import java.util.Scanner;

//T1 to ask elements of the array and display result
class T1 extends Thread {
   int arr[], n;
   Scanner in = new Scanner(System.in);

   public void run() {
       System.out.println("Enter length of the array : ");
       n = in.nextInt();
       arr = new int[n];
       System.out.println("Enter elements of the array : ");
       for (int i = 0; i < arr.length; i++) {
           arr[i] = in.nextInt();
       }
       T2 thread2 = new T2(arr);
       T3 thread3 = new T3(arr);
       thread2.start();
       thread3.start();
       while (thread2.isAlive()) {
           ;
       }
       System.out.println("Maximum Grade of passed student : " + thread2.max);
       while (thread3.isAlive()) {
           ;
       }
       System.out.println("Maximum Grade of failed student : " + thread3.max);
   }
}

//Thread 2 to get max grade of passed student
class T2 extends Thread {
   int max;
   int arr[];

   T2(int arr[]) {
       this.arr = new int[arr.length];
       for (int i = 0; i < arr.length; i++) {
           this.arr[i] = arr[i];
       }
   }

   public void run() {
       int temp[] = new int[arr.length];
       int count = 0;
       for (int i = 0; i < arr.length; i++) {
           if (arr[i] >= 60) {
               temp[count] = arr[i];
               count++;
           }
       }
       max = temp[0];
       for (int i = 0; i < count; i++) {
           if (max < temp[i]) {
               max = temp[i];
           }
       }
   }
}

//thread 3 to get maximum grade of failed student
class T3 extends Thread {
   int max;
   int arr[];

   T3(int arr[]) {
       this.arr = new int[arr.length];
       for (int i = 0; i < arr.length; i++) {
           this.arr[i] = arr[i];
       }
   }

   public void run() {
       int temp[] = new int[arr.length];
       int count = 0;
       for (int i = 0; i < arr.length; i++) {
           if (arr[i] < 60) {
               temp[count] = arr[i];
               count++;
           }
       }
       max = temp[0];
       for (int i = 0; i < count; i++) {
           if (max < temp[i]) {
               max = temp[i];
           }
       }
   }
}

//test class
public class test {
   public static void main(String[] args) {
       T1 thread = new T1();
       thread.start();
   }
}

//Output

Problems @ Javadoc Console x Debug Diagrams <terminated> test (5) [Java Application] C:\Program Files\Java\jre 1.8.0_261\bin\javaw.exe (29 Jul, 2020 11:32:30 PM Enter length of the array : 5 Enter elements of the array: 67 83 49 57 93 Maximum Grade of passed student : 93 Maximum Grade of failed student : 57