nextfit.java

// Java program for next fit
// memory management algorithm
import java.util.*;
 
public class nextfit {
 
// Function to allocate memory to blocks as per Next fit
// algorithm
    static void NextFit(int blockSize[], int m, int processSize[], int n) {
        // Stores block id of the block allocated to a
        // process
        int allocation[] = new int[n], j = 0, t = m - 1;
 
        // Initially no block is assigned to any process
        Arrays.fill(allocation, -1);
 
        // pick each process and find suitable blocks
        // according to its size ad assign to it
       // pick each process and find sui                    table blocks
    // according to its size ad assign to it
    for(int i = 0; i < n; i++){
 
        // Do not start from beginning
        while (j < m){
            if(blockSize[j] >= processSize[i]){
                 
                // allocate block j to p[i] process
                allocation[i] = j;
                 
                // Reduce available memory in this block.
                blockSize[j] -= processSize[i];
                 
                // sets a new end point
                t = (j - 1) % m;
                break;
            }
            if (t == j){
                // sets a new end point
                t = (j - 1) % m;
                // breaks the loop after going through all memory block
                break;
            }
             
            // mod m will help in traversing the
            // blocks from starting block after
            // we reach the end.
            j = (j + 1) % m;
        }
    }
 
        System.out.print("\nProcess No.\tProcess Size\tBlock no.\n");
        for (int i = 0; i < n; i++) {
            System.out.print( i + 1 + "\t\t" + processSize[i]
                    + "\t\t");
            if (allocation[i] != -1) {
                System.out.print(allocation[i] + 1);
            } else {
                System.out.print("Not Allocated");
            }
            System.out.println("");
        }
    }
 
// Driver program
    public static void main(String[] args) {
        int blockSize[] = {5, 10, 20};
        int processSize[] = {10, 20, 5};
        int m = blockSize.length;
        int n = processSize.length;
        NextFit(blockSize, m, processSize, n);
    }
}