FCFS.java

// Java program for implementation of FCFS
// scheduling

import java.text.ParseException;

class FCFS {

	// Function to find the waiting time for all
	// processes
	static void findWaitingTime(int processes[], int n,
			int bt[], int wt[]) {
		// waiting time for first process is 0
		wt[0] = 0;

		// calculating waiting time
		for (int i = 1; i < n; i++) {
			wt[i] = bt[i - 1] + wt[i - 1];
		}
	}

	// Function to calculate turn around time
	static void findTurnAroundTime(int processes[], int n,
			int bt[], int wt[], int tat[]) {
		// calculating turnaround time by adding
		// bt[i] + wt[i]
		for (int i = 0; i < n; i++) {
			tat[i] = bt[i] + wt[i];
		}
	}

	//Function to calculate average time
	static void findavgTime(int processes[], int n, int bt[]) {
		int wt[] = new int[n], tat[] = new int[n];
		int total_wt = 0, total_tat = 0;

		//Function to find waiting time of all processes
		findWaitingTime(processes, n, bt, wt);

		//Function to find turn around time for all processes
		findTurnAroundTime(processes, n, bt, wt, tat);

		//Display processes along with all details
		System.out.printf("Processes Burst time Waiting"
					+" time Turn around time\n");

		// Calculate total waiting time and total turn
		// around time
		for (int i = 0; i < n; i++) {
			total_wt = total_wt + wt[i];
			total_tat = total_tat + tat[i];
			System.out.printf(" %d ", (i + 1));
			System.out.printf("	 %d ", bt[i]);
			System.out.printf("	 %d", wt[i]);
			System.out.printf("	 %d\n", tat[i]);
		}
		float s = (float)total_wt /(float) n;
		int t = total_tat / n;
		System.out.printf("Average waiting time = %f", s);
		System.out.printf("\n");
		System.out.printf("Average turn around time = %d ", t);
	}

	// Driver code
	public static void main(String[] args) throws ParseException {
		//process id's
		int processes[] = {1, 2, 3};
		int n = processes.length;

		//Burst time of all processes
		int burst_time[] = {10, 5, 8};

		findavgTime(processes, n, burst_time);

	}
}