From e1cb9f084aa3a574e20c708ca9ad5cb419c86f2a Mon Sep 17 00:00:00 2001
From: Mohanad Talat <mohanadtalat91@gmail.com>
Date: Thu, 28 Apr 2022 05:59:06 +0200
Subject: [PATCH] Add SRTF file

---
 algorithms/Java/scheduling/SRTF.java | 115 +++++++++++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 algorithms/Java/scheduling/SRTF.java

diff --git a/algorithms/Java/scheduling/SRTF.java b/algorithms/Java/scheduling/SRTF.java
new file mode 100644
index 00000000..60c024a0
--- /dev/null
+++ b/algorithms/Java/scheduling/SRTF.java
@@ -0,0 +1,115 @@
+import java.util.ArrayList; 
+import java.util.Scanner;
+import java.util.Collections;
+
+
+public class SRTF implements Comparable<SRTF>{
+	
+	int complete, burst_time, wait_time, id, arrival_time ;
+	int remain_burst_time, turnAround_time ; 
+	
+	public SRTF(int burst_time,int id, int arrival_time) {
+		this.id = id ; 
+		this.arrival_time = arrival_time ; 
+		this.burst_time = burst_time ; 
+		this.wait_time = 0 ; 
+		this.complete = arrival_time ; 
+		this.remain_burst_time = burst_time ; 
+	}
+	
+	public int compareTo(SRTF process) {
+		return this.arrival_time - process.arrival_time ; 
+	}
+
+	public static void main(String[] args) {
+		
+		Scanner input = new Scanner(System.in) ;
+		System.out.print("Enter number of processes : ");
+		int n = input.nextInt() ; 
+		
+		ArrayList<SRTF> arr = new ArrayList<SRTF>() ;
+		
+		for(int i=0 ; i<n ; i++) {
+			System.out.print("Enter id, burst time, arrival time : ");
+			int id=input.nextInt(), burst=input.nextInt(), arrival=input.nextInt() ; 
+			arr.add(new SRTF(burst, id, arrival)) ; 
+		}
+		// Before sorting according to arrival time of each process
+		for(SRTF process : arr) {
+			System.out.println("id: " + process.id + ",  burst: "+process.burst_time + ",  arrival time: " + process.arrival_time);
+		}
+		
+//		Collections.sort(arr); 
+//		To detect the sorting according to arrival time of each process
+//		for(SRTF process : arr) {
+//			System.out.println("id: " + process.id + ",  burst: "+process.burst_time + ",  arrival time: " + process.arrival_time);
+//		}
+		
+		int current_time=0, numOf_process=0 ;
+		
+		Collections.sort(arr);
+
+		while(numOf_process!=n) {
+			ArrayList<Integer> indices = new ArrayList<Integer>() ; 
+			
+			for( int i=0 ; i<n ; i++) {
+				
+				if( arr.get(i).arrival_time<=current_time && arr.get(i).remain_burst_time>0 ) {
+					indices.add(i) ; 
+					arr.get(i).complete++ ;
+				}
+				
+			}
+			if(indices.size() != 0) {
+				int minBurst=arr.get(indices.get(0)).burst_time, idxMinBurst=indices.get(0) ; 
+				for(int i=0 ; i<indices.size() ; i++) {
+					
+					if(arr.get(indices.get(i)).burst_time < minBurst ) {
+						idxMinBurst = indices.get(i) ;
+						minBurst = arr.get(indices.get(i)).burst_time ; 
+					}
+				}
+				arr.get(idxMinBurst).remain_burst_time-- ; 
+			}
+			
+			current_time++ ;
+			
+			for(int i=0 ; i<indices.size() ; i++) {
+				if( arr.get(indices.get(i)).remain_burst_time == 0 ) {
+					numOf_process++ ; 
+				}
+			}
+		}
+		
+		
+		// To handle turn-around time of each process
+		// As known that turn-around time = complete-arrival & wait=turn around - burst time
+		float wait_avg=0, turnAround_avg=0 ; 
+		for(int i=0 ; i<n ; i++) {
+			arr.get(i).turnAround_time = arr.get(i).complete - arr.get(i).arrival_time ;
+			arr.get(i).wait_time = arr.get(i).turnAround_time - arr.get(i).burst_time ;
+			wait_avg += arr.get(i).wait_time ; 
+			turnAround_avg += arr.get(i).turnAround_time ; 
+			//arr.get(i).complete -= arr.get(i).arrival_time ; 
+		}
+		
+		wait_avg /= n ; 
+		turnAround_avg /= n ; 
+		
+		for(SRTF process : arr) {
+			System.out.println();
+			System.out.println("*********************");
+			System.out.println("id: "+process.id+",  burst: "+process.burst_time+",  arrival time: "+process.arrival_time);
+			System.out.println(",  complete time: "+process.complete+",  waiting time: "+process.wait_time+ ",  turn-around time: "+process.turnAround_time) ; 
+		}
+		
+		System.out.println("*********************");
+		System.out.println("The average wait is : " + wait_avg) ; 
+		System.out.println("The average turn-around is : " + turnAround_avg);
+	}
+
+}
+
+
+
+