optimal page replacement in java

Optimal page replacement in java

package pagereplacement;

import java.util.LinkedList;

import java.util.Queue;

import java.util.Scanner;

public class Demo {

String ref="";

int size=0;

int pf=0;

char frame[];

int fc=0;

Scanner input=new Scanner(System.in);

public void input(){

System.out.println("Enter Ref. String");

ref=input.next();

System.out.println("Enter Frame size");

size=input.nextInt();

frame=new char[size];

}

public boolean search(char ch){

for(int i=0;i<fc;i++){

char temp=frame[i];

if(temp==ch){

return true;

}

}

return false;

}

public int future(char ch, int pos){

int result=ref.length()+1;

for(int i=pos+1;i<ref.length();i++){

char temp=ref.charAt(i);

if(temp==ch){

if(i<result){

result=i;

}

}

}

return result;

}

public void optimal(){

System.out.println("Lenght="+ref.length());

for(int i=0;i <ref.length();i++){

char ch=ref.charAt(i);

if(search(ch)){

}else{

// page fault

System.out.print("Page fault At index "+i);

pf++;

if(fc<size){

frame[fc]=ch;

fc++;

}else{

int optimal[]=new int[size];

for(int j=0;j<size;j++){

optimal[j]=future(frame[j],i);

}

// to find the page to be replaced

int index=0;

int max=optimal[0];

for(int j=1;j<size;j++){

if(optimal[j]>max){

max=optimal[j];

index=j;

}

}

// replace page

System.out.print(" and page "+ frame[index]+" is repaced by "+ch);

frame[index]=ch;

}

System.out.println();

}

}

System.out.println("No. of Page fault="+pf);

}

public static void main(String args[]){

Demo obj=new Demo();

obj.input();

obj.optimal();

}

}

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